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<?xml version="1.0"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
]>
<book id="treeview-tutorial">
<bookinfo>
<date>September 1st, 2003</date>
<title>GTK+ 2.0 Tree View Tutorial</title>
<authorgroup>
<author>
<firstname>Tim-Philipp</firstname>
<surname>M&uuml;ller</surname>
</author>
</authorgroup>
<abstract>
<para>
This is a tutorial on how to use the GTK (the GIMP Toolkit)
GtkTreeView widget through its C interface.
</para>
<para>
Please mail all comments and suggestions to <email>tim at centricular dot net</email>
</para>
<para>
A tarball of the tutorial for off-line reading including the example source codes
is available here: <ulink url="treeview-tutorial.tar.gz">treeview-tutorial.tar.gz</ulink>.
</para>
<para>
There is also a <ulink url="treeview-tutorial.pdf">version in PDF format</ulink> (for easier
printing) and the raw <ulink url="treeview-tutorial-xml.tar.gz">docbook XML source document</ulink>.
</para>
<para>
This tutorial is work-in-progress. The latest version can
be found at <ulink url="http://scentric.net/tutorial/">
http://scentric.net/tutorial/</ulink>.
</para>
<para>
Some sections are a bit outdated (e.g. GtkTreeModelFilter has been in Gtk since 2.4),
just haven't gotten around to rewrite them or update them. Sorry!
</para>
<para>
Last updated: September 29th, 2006
</para>
</abstract>
</bookinfo>
<toc></toc>
<!-- ***************************************************************** -->
<chapter id="ch-TreeView">
<title>Lists and Trees: the GtkTreeView Widget</title>
<para>
<literal>GtkTreeView</literal> is a widget that displays single- or multi-columned lists and trees.
It replaces the old Gtk+-1.2 GtkCList and GtkCTree widgets. Even though <literal>GtkTreeView</literal> is
slightly harder to master than its predecessors, it is so much more powerful and flexible
that most application developers will not want to miss it once they have come to know it.
</para>
<para>
The purpose of this chapter is not to provide an exhaustive documentation of <literal>GtkTreeView</literal> -
that is what the <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/TreeWidgetObjects.html">API documentation</ulink> is for,
which should be read alongside with this tutorial.
The goal is rather to present an introduction to the most commonly-used aspects of <literal>GtkTreeView</literal>,
and to demonstrate how the various <literal>GtkTreeView</literal> components and concepts work together.
Furthermore, an attempt has been made to shed some light on custom tree models and custom cell renderers,
which seem to be often-mentioned, but rarely explained.
</para>
<para>
Developers looking for a quick and dirty introduction that teaches them everything they need
to know in less than five paragraphs will not find it here. In the author's experience,
developers who do not understand how the tree view and the models work together will run
into problems once they try to modify the given examples, whereas developers who have worked
with other toolkits that employ the Model/View/Controller-design will find that the API reference
provides all the information they need to know in more condensed form anyway. Those who disagree
may jump straight to the <link linkend="sec-treeview-col-example">working example code</link> of course.
</para>
<para>
Please note that the code examples in the following sections do not necessarily demonstrate how
<literal>GtkTreeView</literal> is used best in a particular situation. There are different ways
to achieve the same result, and the examples merely show those different ways, so that developers
are able to decide which one is most suitable for the task at hand.
</para>
<sect1 id="sec-TreeView-HelloWorld">
<title>Hello World</title>
<para>
For the impatient, here is a small treeview 'Hello World' program (which can
also be found in the examples section of the <ulink url="treeview-tutorial.tar.gz">
treeview-tutorial.tar.gz</ulink> tarball).
</para>
<programlisting role="C">
/*
* Compile with:
* gcc -o helloworld helloworld.c `pkg-config --cflags --libs gtk+-2.0`
*
*/
#include &lt;gtk/gtk.h&gt;
enum
{
COL_NAME = 0,
COL_AGE,
NUM_COLS
} ;
static GtkTreeModel *
create_and_fill_model (void)
{
GtkListStore *store;
GtkTreeIter iter;
store = gtk_list_store_new (NUM_COLS, G_TYPE_STRING, G_TYPE_UINT);
/* Append a row and fill in some data */
gtk_list_store_append (store, &amp;iter);
gtk_list_store_set (store, &amp;iter,
COL_NAME, "Heinz El-Mann",
COL_AGE, 51,
-1);
/* append another row and fill in some data */
gtk_list_store_append (store, &amp;iter);
gtk_list_store_set (store, &amp;iter,
COL_NAME, "Jane Doe",
COL_AGE, 23,
-1);
/* ... and a third row */
gtk_list_store_append (store, &amp;iter);
gtk_list_store_set (store, &amp;iter,
COL_NAME, "Joe Bungop",
COL_AGE, 91,
-1);
return GTK_TREE_MODEL (store);
}
static GtkWidget *
create_view_and_model (void)
{
GtkCellRenderer *renderer;
GtkTreeModel *model;
GtkWidget *view;
view = gtk_tree_view_new ();
/* --- Column #1 --- */
renderer = gtk_cell_renderer_text_new ();
gtk_tree_view_insert_column_with_attributes (GTK_TREE_VIEW (view),
-1,
"Name",
renderer,
"text", COL_NAME,
NULL);
/* --- Column #2 --- */
renderer = gtk_cell_renderer_text_new ();
gtk_tree_view_insert_column_with_attributes (GTK_TREE_VIEW (view),
-1,
"Age",
renderer,
"text", COL_AGE,
NULL);
model = create_and_fill_model ();
gtk_tree_view_set_model (GTK_TREE_VIEW (view), model);
/* The tree view has acquired its own reference to the
* model, so we can drop ours. That way the model will
* be freed automatically when the tree view is destroyed */
g_object_unref (model);
return view;
}
int
main (int argc, char **argv)
{
GtkWidget *window;
GtkWidget *view;
gtk_init (&amp;argc, &amp;argv);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
g_signal_connect (window, "delete_event", gtk_main_quit, NULL); /* dirty */
view = create_view_and_model ();
gtk_container_add (GTK_CONTAINER (window), view);
gtk_widget_show_all (window);
gtk_main ();
return 0;
}
</programlisting>
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-treeview-components">
<title>Components: Model, Renderer, Column, View</title>
<para>
The most important concept underlying <literal>GtkTreeView</literal> is that of complete
separation between data and how that data is displayed on the screen. This is commonly known
as Model/View/Controller-design (MVC). Data of various type (strings, numbers, images, etc.)
is stored in a 'model'. The 'view' is then told which data to display, where to display it,
and how to display it. One of the advantages of this approach is that you can have multiple
views that display the same data (a directory tree for example) in different ways, or in the
same way multiple times, with only one copy of the underlying data. This avoids duplication of
data and programming effort if the same data is re-used in different contexts. Also, when the
data in the model is updated, all views automatically get updated as well.
</para>
<para>
So, while <literal>GtkTreeModel</literal> is used to store data, there are other components
that determine which data is displayed in the <literal>GtkTreeView</literal> and how it is
displayed. These components are <literal>GtkTreeViewColumn</literal> and <literal>GtkCellRenderer</literal>.
A <literal>GtkTreeView</literal> is made up of tree view columns. These
are the columns that users perceive as columns. They have a clickable column header with a
column title that can be hidden, and can be resized and sorted. Tree view columns do not
display any data, they are only used as a device to represent the user-side of the tree view
(sorting etc.) and serve as packing widgets for the components that do the actual rendering
of data onto the screen, namely the <literal>GtkCellRenderer</literal> family of objects (I call them 'objects'
because they are not GtkWidgets). There are a number of different cell renderers that specialise
in rendering certain data like strings, pixbufs, or toggle buttons. More on this <link linkend="sec-renderer">later</link>.
</para>
<para>
Cell renderers are packed into tree view columns to display data. A tree view column needs to contain at least one cell
renderer, but can contain multiple cell renderers. For example, if one wanted to display a 'Filename' column where each
filename has a little icon on the left indicating the file type, one would pack a <literal>GtkCellRendererPixbuf</literal>
and a <literal>GtkCellRendererText</literal> into one tree view column. Packing renderers into a tree view column is
similar to packing widgets into a <literal>GtkHBox</literal>.
</para>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-treemodels">
<title>GtkTreeModels for Data Storage: GtkListStore and GtkTreeStore</title>
<para>
It is important to realise what <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html"><literal>GtkTreeModel</literal></ulink>
is and what it is not. <literal>GtkTreeModel</literal> is basically just an 'interface' to the data store,
meaning that it is a standardised set of functions that allows a <literal>GtkTreeView</literal> widget
(and the application programmer) to query certain characteristics of a data store,
for example how many rows there are, which rows have children, and how many children a particular row has.
It also provides functions to retrieve data from the data store, and tell the tree view what type of data
is stored in the model. Every data store must implement the <literal>GtkTreeModel</literal> interface and
provide these functions, which you can use by casting a store to a tree model with
<literal>GTK_TREE_MODEL(store)</literal>. <literal>GtkTreeModel</literal> itself only provides a way to
query a data store's characteristics and to retrieve existing data, it does not provide a way to remove
or add rows to the store or put data into the store. This is done using the specific store's functions.
</para>
<para>
Gtk+ comes with two built-in data stores (models):
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkListStore.html"><literal>GtkListStore</literal></ulink> and
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeStore.html"><literal>GtkTreeStore</literal></ulink>.
As the names imply, <literal>GtkListStore</literal> is used for simple lists of data items where items have
no hierarchical parent-child relationships, and <literal>GtkTreeStore</literal> is used for tree-like data
structures, where items can have parent-child relationships. A list of files in a directory would be an example
of a simple list structure, whereas a directory tree is an example for a tree structure. A list is
basically just a special case of a tree with none of the items having any children, so one could use
a tree store to maintain a simple list of items as well. The only reason <literal>GtkListStore</literal>
exists is in order to provide an easier interface that does not need to cater for child-parent relationships,
and because a simple list model can be optimised for the special case where no children exist, which makes
it faster and more efficient.
</para>
<para>
<literal>GtkListStore</literal> and <literal>GtkTreeStore</literal> should cater for most types of data an
application developer might want to display in a <literal>GtkTreeView</literal>. However, it should be noted
that <literal>GtkListStore</literal> and <literal>GtkTreeStore</literal> have been designed with flexibility in
mind. If you plan to store a lot of data, or have a large number of rows, you should consider implementing your own
custom model that stores and manipulates data your own way and implements the <literal>GtkTreeModel</literal>
interface. This will not only be more efficient, but probably also lead to saner code in the long run, and give
you more control over your data. See <link linkend="sec-custom-models">below</link> for more details on how
to implement custom models.
</para>
<para>
Tree model implementations like <literal>GtkListStore</literal> and <literal>GtkTreeStore</literal> will take
care of the view side for you once you have configured the <literal>GtkTreeView</literal> to display what you
want. If you change data in the store, the model will notify the tree view and your data display will be
updated. If you add or remove rows, the model will also notify the store, and your row will appear in or
disappear from the view as well.
</para>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-data">
<title>How Data is Organised in a Store</title>
<para>
A model (data store) has model columns and rows. While a tree view will display each row in the model as a row
in the view, the model's columns are not to be confused with a view's columns. A model column represents a certain
data field of an item that has a fixed data type. You need to know what kind of data you want to store when you
create a list store or a tree store, as you can not add new fields later on.
</para>
<para>
For example, we might want to display a list of files. We would create a list store with two fields: a field
that stores the filename (ie. a string) and a field that stores the file size (ie. an unsigned integer).
The filename would be stored in column 0 of the model, and the file size would be stored in column 1 of the model.
For each file we would add a row to the list store, and set the row's fields to the filename and the file size.
</para>
<para>
The <ulink url="http://developer.gnome.org/doc/API/2.0/gobject/gobject-GType.html">GLib type system (GType)</ulink>
is used to indicate what type of data is stored in a model column. These are the most commonly used types:
</para>
<itemizedlist>
<listitem>
<simpara>
<literal>G_TYPE_BOOLEAN</literal>
</simpara>
</listitem>
<listitem>
<simpara>
<literal>G_TYPE_INT</literal>, <literal>G_TYPE_UINT</literal>
</simpara>
</listitem>
<listitem>
<simpara>
<literal>G_TYPE_LONG</literal>, <literal>G_TYPE_ULONG</literal>, <literal>G_TYPE_INT64</literal>, <literal>G_TYPE_UINT64</literal> (these are not supported in early gtk+-2.0.x versions)
</simpara>
</listitem>
<listitem>
<simpara>
<literal>G_TYPE_FLOAT</literal>, <literal>G_TYPE_DOUBLE</literal>
</simpara>
</listitem>
<listitem>
<simpara>
<literal>G_TYPE_STRING</literal> - stores a string in the store (makes a copy of the original string)
</simpara>
</listitem>
<listitem>
<simpara>
<literal>G_TYPE_POINTER</literal> - stores a pointer value (does not copy any data into the store, just stores the pointer value!)
</simpara>
</listitem>
<listitem>
<simpara>
<literal>GDK_TYPE_PIXBUF</literal> - stores a GdkPixbuf in the store (increases the pixbuf's
refcount, <link linkend="sec-treemodel-storing-gobjects">see below</link>)
</simpara>
</listitem>
</itemizedlist>
<para>
You do not need to understand the type system, it will usually suffice to know the above types,
so you can tell a list store or tree store what kind of data you want to store. Advanced users can derive
their own types from the fundamental GLib types. For simple structures you could
<ulink url="http://developer.gnome.org/doc/API/2.0/gobject/gobject-Boxed-Types.html#g-boxed-type-register-static">register</ulink>
a new <ulink url="http://developer.gnome.org/doc/API/2.0/gobject/gobject-Boxed-Types.html">boxed type</ulink>
for example, but that is usually not necessary. <literal>G_TYPE_POINTER</literal> will often do as well, you
will just need to take care of memory allocation and freeing yourself then.
</para>
<para>
Storing <literal>GObject</literal>-derived types (most <literal>GDK_TYPE_FOO</literal>
and <literal>GTK_TYPE_FOO</literal>) is a special case that is dealt with
<link linkend="sec-treemodel-storing-gobjects">further below</link>.
</para>
<para>
Here is an example of how to create a list store:
</para>
<programlisting role="C">
GtkListStore *list_store;
list_store = gtk_list_store_new (2, G_TYPE_STRING, G_TYPE_UINT);
</programlisting>
<para>
This creates a new list store with two columns. Column 0 stores a string and column 1 stores an unsigned integer for each row.
At this point the model has no rows yet of course. Before we start to add rows, let's have a look at the different ways used
to refer to a particular row.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-rowref">
<title>Refering to Rows: GtkTreeIter, GtkTreePath, GtkTreeRowReference</title>
<para>
There are different ways to refer to a specific row. The two you will have to deal with are
<literal>GtkTreeIter</literal> and <literal>GtkTreePath</literal>.
</para>
<sect2 id="sec-treemodel-rowref-path">
<title>GtkTreePath</title>
<subtitle>Describing a row 'geographically'</subtitle>
<para>
A <literal>GtkTreePath</literal> is a comparatively straight-forward way to describe the
logical position of a row in the model. As a <literal>GtkTreeView</literal> always displays
<emphasis>all</emphasis> rows in a model, a tree path always describes the same row in both model and view.
</para>
<figure id="sec-treemodel-treepath-sshot">
<title>Tree Paths</title>
<screenshot>
<mediaobject>
<imageobject>
<imagedata fileref="images/treepath.png" format="PNG" />
</imageobject>
<imageobject>
<imagedata fileref="images/treepath.eps" format="EPS" />
</imageobject>
</mediaobject>
</screenshot>
</figure>
<para>
The picture shows the tree path in string form next to the label. Basically,
it just counts the children from the imaginary root of the tree view. An
empty tree path string would specify that imaginary invisible root. Now
'Songs' is the first child (from the root) and thus its tree path is just "0".
'Videos' is the second child from the root, and its tree path is "1". 'oggs'
is the second child of the first item from the root, so its tree path is "0:1".
So you just count your way down from the root to the row in question, and you
get your tree path.
</para>
<para>
To clarify this, a tree path of "3:9:4:1" would basically mean
<emphasis>in human language</emphasis> (attention - this is not what it really means!)
something along the lines of: go to the 3rd top-level row. Now go to the 9th child
of that row. Proceed to the 4th child of the previous row. Then continue to the
1st child of that. Now you are at the row this tree path describes.
This is not what it means for Gtk+ though. While humans start counting at 1, computers
usually start counting at 0. So the real meaning of the tree path "3:9:4:1" is: Go to the
4th top-level row. Then go to the 10th child of that row. Pick the 5th child of that row. Then
proceed to the 2nd child of the previous row. Now you are at the row this
tree path describes. :)
</para>
<para>
The implication of this way of refering to rows is as follows: if you insert or delete
rows in the middle or if the rows are resorted, a tree path might suddenly refer to a
completely different row than it refered to before the insertion/deletion/resorting. This
is important to keep in mind.
(See the <link linkend="sec-treemodel-rowref-rowref">section on
<literal>GtkTreeRowReference</literal>s below</link> for a tree path that keeps updating
itself to make sure it always refers to the same row when the model changes).
</para>
<para>
This effect becomes apparent if you imagine what would happen if we were to delete the
row entitled 'funny clips' from the tree in the above picture. The row 'movie trailers' would
suddenly be the first and only child of 'clips', and be described by the tree path that
formerly belonged to 'funny clips', ie. "1:0:0".
</para>
<para>
You can get a new <literal>GtkTreePath</literal> from a
path in string form using <literal>gtk_tree_path_new_from_string</literal>,
and you can convert a given <literal>GtkTreePath</literal> into its string
notation with <literal>gtk_tree_path_to_string</literal>. Usually you will
rarely have to handle the string notation, it is described here merely to
demonstrate the concept of tree paths.
</para>
<para>
Instead of the string notation, <literal>GtkTreePath</literal> uses an integer
array internally. You can get the depth (ie. the nesting level) of a tree path
with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-get-depth">
<literal>gtk_tree_path_get_depth</literal></ulink>. A depth of 0 is the imaginary
invisible root node of the tree view and model. A depth of 1 means that the
tree path describes a top-level row. As lists are just trees without child nodes,
all rows in a list always have tree paths of depth 1.
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-get-indices">
<literal>gtk_tree_path_get_indices</literal></ulink> returns the internal integer
array of a tree path. You will rarely need to operate with those either.
</para>
<para>
If you operate with tree paths, you are most likely to use a given tree path,
and use functions like
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk_tree_path_up">
<literal>gtk_tree_path_up</literal></ulink>,
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-down">
<literal>gtk_tree_path_down</literal></ulink>,
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-next">
<literal>gtk_tree_path_next</literal></ulink>,
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-prev">
<literal>gtk_tree_path_prev</literal></ulink>,
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-is-ancestor">
<literal>gtk_tree_path_is_ancestor</literal></ulink>, or
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-is-descendant">
<literal>gtk_tree_path_is_descendant</literal></ulink>.
Note that this way you can construct and operate on tree paths that refer to
rows that do not exist in model or view! The only way to check whether a
path is valid for a specific model (ie. the row described by the path exists)
is to convert the path into an iter using
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-iter">
<literal>gtk_tree_model_get_iter</literal></ulink>.
</para>
<para>
<literal>GtkTreePath</literal> is an opaque structure, with its details hidden from the compiler.
If you need to make a copy of a tree path, use
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-copy">
<literal>gtk_tree_path_copy</literal></ulink>.
</para>
</sect2>
<sect2 id="sec-treemodel-rowref-iter">
<title>GtkTreeIter</title>
<subtitle>Refering to a row in model-speak</subtitle>
<para>
Another way to refer to a row in a list or tree is <literal>GtkTreeIter</literal>. A tree iter is just a
structure that contains a couple of pointers that mean something to the model you are using. Tree iters are
used internally by models, and they often contain a direct pointer to the internal data of the row in question.
You should never look at the content of a tree iter and you must not modify it directly either.
</para>
<para>
All tree models (and therefore also <literal>GtkListStore</literal> and <literal>GtkTreeStore</literal>)
must support the <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html">
<literal>GtkTreeModel</literal></ulink> functions that operate on tree iters (e.g. get
the tree iter for the first child of the row specified by a given tree iter, get the first row in the
list/tree, get the n-th child of a given iter etc.). Some of these functions are:
</para>
<itemizedlist>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-iter-first">
<literal>gtk_tree_model_get_iter_first</literal></ulink> - sets the given iter to the first top-level item in the list or tree
</simpara>
</listitem>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-next">
<literal>gtk_tree_model_iter_next</literal></ulink> - sets the given iter to the next item at the current level in a list or tree.
</simpara>
</listitem>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-children">
<literal>gtk_tree_model_iter_children</literal></ulink> - sets the first given iter to the first child of the row referenced by
the second iter (not very useful for lists, mostly useful for trees).
</simpara>
</listitem>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-n-children">
<literal>gtk_tree_model_iter_n_children</literal></ulink> - returns the number of children the row referenced by the provided
iter has. If you pass <literal>NULL</literal> instead of a pointer to an iter structure, this function will return
the number of top-level rows. You can also use this function to count the number of items in a list store.
</simpara>
</listitem>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-nth-child">
<literal>gtk_tree_model_iter_nth_child</literal></ulink> - sets the first iter to the n-th child of the row referenced
by the second iter. If you pass <literal>NULL</literal> instead of a pointer to an iter structure as the second
iter, you can get the first iter set to the n-th row of a list.
</simpara>
</listitem>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-parent">
<literal>gtk_tree_model_iter_parent</literal></ulink> - sets the first iter to the parent of the row referenced by the
second iter (does nothing for lists, only useful for trees).
</simpara>
</listitem>
</itemizedlist>
<para>
Almost all of those functions return <literal>TRUE</literal> if the requested operation succeeded, and
return <literal>FALSE</literal> otherwise. There are more functions that operate on iters. Check out the
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html">
<literal>GtkTreeModel</literal> API reference</ulink> for details.
</para>
<para>
You might notice that there is no <literal>gtk_tree_model_iter_prev</literal>. This is unlikely to be
implemented for a variety of reasons. It should be fairly simple to write a helper function that provides
this functionality though once you have read this section.
</para>
<para>
Tree iters are used to retrieve data from the store, and to put data into the store. You also get a tree iter
as result if you add a new row to the store using <literal>gtk_list_store_append</literal> or
<literal>gtk_tree_store_append</literal>.
</para>
<para>
Tree iters are often only valid for a short time, and might become invalid if the store changes with some
models. It is therefore usually a bad idea to store tree iters, unless you really know what you are doing.
You can use <literal>gtk_tree_model_get_flags</literal> to get a model's flags, and check whether the
<literal>GTK_TREE_MODEL_ITERS_PERSIST</literal> flag is set (in which case a tree iter will be valid as
long as a row exists), yet still it is not advisable to store iter structures unless you really mean to
do that. There is a better way to keep track of a row over time: <literal>GtkTreeRowReference</literal>
</para>
</sect2>
<sect2 id="sec-treemodel-rowref-rowref">
<title>GtkTreeRowReference</title>
<subtitle>Keeping track of rows even when the model changes</subtitle>
<para>
A <literal>GtkTreeRowReference</literal> is basically an object that takes a tree path,
and watches a model for changes. If anything changes, like rows getting inserted or
removed, or rows getting re-ordered, the tree row reference object will keep the given
tree path up to date, so that it always points to the same row as before. In case the
given row is removed, the tree row reference will become invalid.
</para>
<para>
A new tree row reference can be created with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-row-reference-new">
<literal>gtk_tree_row_reference_new</literal></ulink>, given a model and a tree path. After
that, the tree row reference will keep updating the path whenever the model changes. The current
tree path of the row originally refered to when the tree row reference was created can be
retrieved with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-row-reference-get-path">
<literal>gtk_tree_row_reference_get_path</literal></ulink>. If the row has been deleted,
<literal>NULL</literal> will be returned instead of of a tree path. The tree path returned
is a <emphasis>copy</emphasis>, so it will need to be freed with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-free">
<literal>gtk_tree_path_free</literal></ulink> when it is no longer needed.
</para>
<para>
You can check whether the row referenced still exists with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-row-reference-valid">
<literal>gtk_tree_row_reference_valid</literal></ulink>, and free it with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-row-reference-free">
<literal></literal></ulink> when no longer needed.
</para>
<para>
For the curious: internally, the tree row reference connects to the tree model&apos;s
<literal>"row-inserted"</literal>, <literal>"row-deleted"</literal>, and
<literal>"rows-reordered"</literal> signals and updates its internal tree path
whenever something happened to the model that affects the position of the
referenced row.
</para>
<para>
Note that using tree row references entails a small overhead. This is hardly significant
for 99.9% of all applications out there, but when you have multiple thousands of rows
and/or row references, this might be something to keep in mind (because whenever rows are
inserted, removed, or reordered, a signal will be sent out and processed for each
row reference).
</para>
<para>
If you have read the tutorial only up to here so far, it is hard to
explain really what tree row references are good for. An example
where tree row references come in handy can be found further below
in the <link linkend="sec-treemodel-remove-many-rows">section on removing multiple rows in one go</link>.
</para>
<para>
In practice, a programmer can either use tree row references to keep track of rows over time,
or store tree iters directly (if, and only if, the model has persistent iters). Both
<literal>GtkListStore</literal> and <literal>GtkTreeStore</literal> have persistent iters,
so storing iters is possible. However, using tree row references is definitively the
Right Way(tm) to do things, even though it comes with some overhead that might impact
performance in case of trees that have a very large number of rows (in that
case it might be preferable to write a custom model anyway though). Especially beginners
might find it easier to handle and store tree row references than iters, because tree
row references are handled by pointer value, which you can easily add to a <literal>GList</literal>
or pointer array, while it is easy to store tree iters in a wrong way.
</para>
</sect2>
<sect2 id="sec-treemodel-rowref-usage">
<title>Usage</title>
<para>
Tree iters can easily be converted into tree paths using
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-path">
<literal>gtk_tree_model_get_path</literal></ulink>, and tree
paths can easily be converted into tree iters using
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-iter">
<literal>gtk_tree_model_get_iter</literal></ulink>.
Here is an example that shows how to get the iter from the tree path that
is passed to us from the tree view in the <literal>"row-activated"</literal>
signal callback. We need the iter here to retrieve data from the store
</para>
<programlisting role="C">
/************************************************************
* *
* Converting a GtkTreePath into a GtkTreeIter *
* *
************************************************************/
/************************************************************
*
* onTreeViewRowActivated: a row has been double-clicked
*
************************************************************/
void
onTreeViewRowActivated (GtkTreeView *view, GtkTreePath *path,
GtkTreeViewColumn *col, gpointer userdata)
{
GtkTreeIter iter;
GtkTreeModel *model;
model = gtk_tree_view_get_model(view);
if (gtk_tree_model_get_iter(model, &amp;iter, path))
{
gchar *name;
gtk_tree_model_get(model, &amp;iter, COL_NAME, &amp;name, -1);
g_print ("The row containing the name '%s' has been double-clicked.\n", name);
g_free(name);
}
}
</programlisting>
<para>
Tree row references
reveal the current path of a row with <literal>gtk_tree_row_reference_get_path</literal>. There is no direct
way to get a tree iter from a tree row reference, you have to retrieve the tree row reference's path first and
then convert that into a tree iter.
</para>
<para>
As tree iters are only valid for a short time, they are usually allocated on the stack, as in
the following example (keep in mind that <literal>GtkTreeIter</literal> is just a structure
that contains data fields you do not need to know anything about):
</para>
<programlisting role="C">
/************************************************************
* *
* Going through every row in a list store *
* *
************************************************************/
void
traverse_list_store (GtkListStore *liststore)
{
GtkTreeIter iter;
gboolean valid;
g_return_if_fail ( liststore != NULL );
/* Get first row in list store */
valid = gtk_tree_model_get_iter_first(GTK_TREE_MODEL(liststore), &amp;iter);
while (valid)
{
/* ... do something with that row using the iter ... */
/* (Here column 0 of the list store is of type G_TYPE_STRING) */
gtk_list_store_set(liststore, &amp;iter, 0, "Joe", -1);
/* Make iter point to the next row in the list store */
valid = gtk_tree_model_iter_next(GTK_TREE_MODEL(liststore), &amp;iter);
}
}
</programlisting>
<para>
The code above asks the model to fill the iter structure to make it point to the first
row in the list store. If there is a first row and the list store is not empty, the
iter will be set, and <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-iter-first">
<literal>gtk_tree_model_get_iter_first</literal></ulink> will return
<literal>TRUE</literal>. If there is no first row, it will just return <literal>FALSE</literal>.
If a first row exists, the while loop will be entered and we change some of the first
row's data. Then we ask the model to make the given iter point to the next row, until there
are no more rows, which is when <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-next">
<literal>gtk_tree_model_iter_next</literal></ulink> returns <literal>FALSE</literal>.
Instead of traversing the list store we could also have used
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-foreach">
<literal>gtk_tree_model_foreach</literal></ulink>
</para>
</sect2>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-add-rows">
<title>Adding Rows to a Store</title>
<!-- ************************************************************** -->
<sect2 id="sec-liststore-add-rows">
<title>Adding Rows to a List Store</title>
<para>
Rows are added to a list store with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkListStore.html#gtk-list-store-append">
<literal>gtk_list_store_append</literal></ulink>.
This will insert a new empty row at the end of the list. There are other functions,
documented in the <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkListStore.html">
GtkListStore API reference</ulink>, that give you more control
about where exactly the new row is inserted, but as they work very similar to
<literal>gtk_list_store_append</literal> and are fairly straight-forward to use,
we will not deal with them here.
</para>
<para>
Here is a simple example of how to create a list store and add some (empty) rows to it:
</para>
<programlisting role="C">
GtkListStore *liststore;
GtkTreeIter iter;
liststore = gtk_list_store_new(1, G_TYPE_STRING);
/* Append an empty row to the list store. Iter will point to the new row */
gtk_list_store_append(liststore, &amp;iter);
/* Append an empty row to the list store. Iter will point to the new row */
gtk_list_store_append(liststore, &amp;iter);
/* Append an empty row to the list store. Iter will point to the new row */
gtk_list_store_append(liststore, &amp;iter);
</programlisting>
<para>
This in itself is not very useful yet of course. We will add data to the rows in the next section.
</para>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-treestore-add-rows">
<title>Adding Rows to a Tree Store</title>
<para>
Adding rows to a tree store works similar to adding rows to a list store, only that
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeStore.html#gtk-tree-store-append">
<literal>gtk_tree_store_append</literal></ulink> is the function to use and one more
argument is required, namely the tree iter to the parent of the row to insert.
If you supply NULL instead of providing the tree iter of another row, a new top-level
row will be inserted. If you do provide a parent tree iter, the new empty row will be
inserted after any already existing children of the parent. Again, there are other ways
to insert a row into the tree store and they are documented in the
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeStore.html">
GtkTreeStore API reference manual</ulink>. Another short example:
</para>
<programlisting role="C">
GtkTreeStore *treestore;
GtkTreeIter iter, child;
treestore = gtk_tree_store_new(1, G_TYPE_STRING);
/* Append an empty top-level row to the tree store.
* Iter will point to the new row */
gtk_tree_store_append(treestore, &amp;iter, NULL);
/* Append another empty top-level row to the tree store.
* Iter will point to the new row */
gtk_tree_store_append(treestore, &amp;iter, NULL);
/* Append a child to the row we just added.
* Child will point to the new row */
gtk_tree_store_append(treestore, &amp;child, &amp;iter);
/* Get the first row, and add a child to it as well (could have been done
* right away earlier of course, this is just for demonstration purposes) */
if (gtk_tree_model_get_iter_first(GTK_TREE_MODEL(treestore), &amp;iter))
{
/* Child will point to new row */
gtk_tree_store_append(treestore, &amp;child, &amp;iter);
}
else
{
g_error("Oops, we should have a first row in the tree store!\n");
}
</programlisting>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-treestore-adding-many-rows">
<title>Speed Issues when Adding a Lot of Rows</title>
<para>
A common scenario is that a model needs to be filled with a lot of rows at some point, either at start-up,
or when some file is opened. An equally common scenario is that this takes an awfully long time even on powerful
machines once the model contains more than a couple of thousand rows, with an exponentially decreasing rate of
insertion. As already pointed out above, <link linkend="sec-custom-models">writing a custom model</link>
might be the best thing to do in this case. Nevertheless, there are some things you can do to work around
this problem and speed things up a bit even with the stock Gtk+ models:
</para>
<para>
Firstly, you should detach your list store or tree store from the tree view before doing your mass insertions, then
do your insertions, and only connect your store to the tree view again when you are done with your insertions. Like this:
</para>
<programlisting role="C">
...
model = gtk_tree_view_get_model(GTK_TREE_VIEW(view));
g_object_ref(model); /* Make sure the model stays with us after the tree view unrefs it */
gtk_tree_view_set_model(GTK_TREE_VIEW(view), NULL); /* Detach model from view */
... insert a couple of thousand rows ...
gtk_tree_view_set_model(GTK_TREE_VIEW(view), model); /* Re-attach model to view */
g_object_unref(model);
...
</programlisting>
<para>
Secondly, you should make sure that sorting is disabled while you are doing your mass insertions, otherwise your store
might be resorted after each and every single row insertion, which is going to be everything but fast.
</para>
<para>
Thirdly, you should not keep around a lot of tree row references if you have so many rows, because with each
insertion (or removal) every single tree row reference will check whether its path needs to be updated or not.
</para>
</sect2>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-data-manipulation">
<title>Manipulating Row Data</title>
<para>
Adding empty rows to a data store is not terribly exciting, so let's see how we can add or change data in the store.
</para>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkListStore.html#gtk-list-store-set">
<literal>gtk_list_store_set</literal></ulink> and
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeStore.html#gtk-tree-store-set">
<literal>gtk_tree_store_set</literal></ulink> are used
to manipulate a given row's data. There is also <literal>gtk_list_store_set_value</literal>
and <literal>gtk_tree_store_set_value</literal>, but those should only be used by people
familiar with GLib's GValue system.
</para>
<para>
Both <literal>gtk_list_store_set</literal> and <literal>gtk_tree_store_set</literal> take
a variable number of arguments, and must be terminated with a -1 argument. The first two
arguments are a pointer to the model, and the iter pointing to the row whose data we want
to change. They are followed by a variable number of (column, data) argument pairs,
terminated by a -1. The column refers to the model column number and is usually an enum
value (to make the code more readable and to make changes easier). The data should be of
the same data type as the model column.
</para>
<para>
Here is an example where we create a store that stores two strings and one integer for each row:
</para>
<programlisting role="C">
enum
{
COL_FIRST_NAME = 0,
COL_LAST_NAME,
COL_YEAR_BORN,
NUM_COLS
};
GtkListStore *liststore;
GtkTreeIter iter;
liststore = gtk_list_store_new(NUM_COLS, G_TYPE_STRING, G_TYPE_STRING, G_TYPE_UINT);
/* Append an empty row to the list store. Iter will point to the new row */
gtk_list_store_append(liststore, &amp;iter);
/* Fill fields with some data */
gtk_list_store_set (liststore, &amp;iter,
COL_FIRST_NAME, "Joe",
COL_LAST_NAME, "Average",
COL_YEAR_BORN, (guint) 1970,
-1);
</programlisting>
<para>
You do not need to worry about allocating and freeing memory for the data to store.
The model (or more precisely: the GLib/GObject GType and GValue system) will take care of that for you.
If you store a string, for example, the model will make a copy of the string and store that. If you then
set the field to a new string later on, the model will automatically free the old string and again make
a copy of the new string and store the copy. This applies to almost all types, be it
<literal>G_TYPE_STRING</literal> or <literal>GDK_TYPE_PIXBUF</literal>.
</para>
<para>
The exception to note is <literal>G_TYPE_POINTER</literal>. If you allocate a chunk of
data or a complex structure and store it in a <literal>G_TYPE_POINTER</literal> field,
only the pointer <emphasis>value</emphasis> is stored. The model does not know anything
about the size or content of the data your pointer refers to, so it could not even make
a copy if it wanted to, so you need to allocate and free the memory yourself in this case.
However, if you do not want to do that yourself and want the model to take care of your
custom data for you, then you need to register your own type and derive it from one of
the GLib fundamental types (usually <ulink url="http://developer.gnome.org/doc/API/2.0/gobject/gobject-Boxed-Types.html">G_TYPE_BOXED</ulink>).
See the GObject <ulink url="http://developer.gnome.org/doc/API/2.0/gobject/gobject-GType.html">GType reference manual</ulink>
for details. Making a copy of data involves memory allocation and other overhead of course,
so one should consider the performance implications of using a custom GLib type over a
G_TYPE_POINTER carefully before taking that approach. Again, a custom model might be the
better alternative, depending on the overall amount of data to be stored (and retrieved).
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-data-retrieval">
<title>Retrieving Row Data</title>
<para>
Storing data is not very useful if it cannot be retrieved again. This is done using
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get">
<literal>gtk_tree_model_get</literal></ulink>, which takes similar arguments as
<literal>gtk_list_store_set</literal> or <literal>gtk_tree_store_set</literal> do, only
that it takes (column, pointer) arguments. The pointer must point to a variable that is
of the same type as the data stored in that particular model column.
</para>
<para>
Here is the previous example extended to traverse the list store and print out the data stored.
As an extra, we use <literal>gtk_tree_model_foreach</literal> to traverse the store and retrieve
the row number from the <literal>GtkTreePath</literal> passed to us in the foreach callback function:
</para>
<programlisting role="C">
#include &lt;gtk/gtk.h&gt;
enum
{
COL_FIRST_NAME = 0,
COL_LAST_NAME,
COL_YEAR_BORN,
NUM_COLS
};
gboolean
foreach_func (GtkTreeModel *model,
GtkTreePath *path,
GtkTreeIter *iter,
gpointer user_data)
{
gchar *first_name, *last_name, *tree_path_str;
guint year_of_birth;
/* Note: here we use 'iter' and not '&amp;iter', because we did not allocate
* the iter on the stack and are already getting the pointer to a tree iter */
gtk_tree_model_get (model, iter,
COL_FIRST_NAME, &amp;first_name,
COL_LAST_NAME, &amp;last_name,
COL_YEAR_BORN, &amp;year_of_birth,
-1);
tree_path_str = gtk_tree_path_to_string(path);
g_print ("Row %s: %s %s, born %u\n", tree_path_str,
first_name, last_name, year_of_birth);
g_free(tree_path_str);
g_free(first_name); /* gtk_tree_model_get made copies of */
g_free(last_name); /* the strings for us when retrieving them */
return FALSE; /* do not stop walking the store, call us with next row */
}
void
create_and_fill_and_dump_store (void)
{
GtkListStore *liststore;
GtkTreeIter iter;
liststore = gtk_list_store_new(NUM_COLS, G_TYPE_STRING, G_TYPE_STRING, G_TYPE_UINT);
/* Append an empty row to the list store. Iter will point to the new row */
gtk_list_store_append(liststore, &amp;iter);
/* Fill fields with some data */
gtk_list_store_set (liststore, &amp;iter,
COL_FIRST_NAME, "Joe",
COL_LAST_NAME, "Average",
COL_YEAR_BORN, (guint) 1970,
-1);
/* Append another row, and fill in some data */
gtk_list_store_append(liststore, &amp;iter);
gtk_list_store_set (liststore, &amp;iter,
COL_FIRST_NAME, "Jane",
COL_LAST_NAME, "Common",
COL_YEAR_BORN, (guint) 1967,
-1);
/* Append yet another row, and fill it */
gtk_list_store_append(liststore, &amp;iter);
gtk_list_store_set (liststore, &amp;iter,
COL_FIRST_NAME, "Yo",
COL_LAST_NAME, "Da",
COL_YEAR_BORN, (guint) 1873,
-1);
/* Now traverse the list */
gtk_tree_model_foreach(GTK_TREE_MODEL(liststore), foreach_func, NULL);
}
int
main (int argc, char **argv)
{
gtk_init(&amp;argc, &amp;argv);
create_and_fill_and_dump_store();
return 0;
}
</programlisting>
<para>
Note that when a new row is created, all fields of a row are set to a default NIL value
appropriate for the data type in question. A field of type <literal>G_TYPE_INT</literal>
will automatically contain the value 0 until it is set to a different value, and strings
and all kind of pointer types will be <literal>NULL</literal> until set to something else.
Those are valid contents for the model, and if you are not sure that row contents have
been set to something, you need to be prepared to handle <literal>NULL</literal> pointers
and the like in your code.
</para>
<para>
Run the above program with an additional empty row and look at the output to see
this in effect.
</para>
<sect2 id="sec-treemodel-retrieved-data-disposal">
<title>Freeing Retrieved Row Data</title>
<para>
Unless you are dealing with a model column of type <literal>G_TYPE_POINTER</literal>,
<literal>gtk_tree_model_get</literal> will always make <emphasis>copies</emphasis> of
the data retrieved.
</para>
<para>
In the case of strings, this means that you need to <literal>g_free</literal> the
string returned when you don't need it any longer, as in the example above.
</para>
<para>
If you retrieve a <literal>GObject</literal> such as a <literal>GdkPixbuf</literal>
from the store, <literal>gtk_tree_model_get</literal> will automatically add a
reference to it, so you need to call <literal>g_object_unref</literal> on the
retrieved object once you are done with it:
</para>
<programlisting role="C">
...
GdkPixbuf *pixbuf;
gtk_tree_model_get (model, &amp;iter,
COL_PICTURE, &amp;pixbuf,
NULL);
if (pixbuf != NULL)
{
do_something_with_pixbuf (pixbuf);
g_object_unref (pixbuf);
}
...
</programlisting>
<para>
Similarly, <literal>GBoxed</literal>-derived types retrieved from a model
need to be freed with <literal>g_boxed_free</literal> when done with them
(don't worry if you have never heard of <literal>GBoxed</literal>).
</para>
<para>
If the model column is of type <literal>G_TYPE_POINTER</literal>,
<literal>gtk_tree_model_get</literal> will simply copy the pointer
value, but not the data (even if if it wanted to, it couldn't copy
the data, because it would not know how to copy it or what to copy
exactly). If you store pointers to objects or strings in a pointer
column (which you should not do unless you really know what you are
doing and why you are doing it), you do not need to unref or free
the returned values as described above, because
<literal>gtk_tree_model_get</literal> would not know what kind of
data they are and therefore won't ref or copy them on retrieval.
</para>
</sect2>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-remove-row">
<title>Removing Rows</title>
<para>
Rows can easily be removed with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkListStore.html#gtk-list-store-remove">
<literal>gtk_list_store_remove</literal></ulink> and
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeStore.html#gtk-tree-store-remove">
<literal>gtk_tree_store_remove</literal></ulink>. The removed row will
automatically be removed from the tree view as well, and all data
stored will automatically be freed, with the exception of
<literal>G_TYPE_POINTER</literal> columns (see above).
</para>
<para>
Removing a single row is fairly straight forward: you need to get the iter that
identifies the row you want to remove, and then use one of the above functions.
Here is a simple example that removes a row when you double-click on it (bad from
a user interface point of view, but then it is just an example):
</para>
<programlisting role="C">
static void
onRowActivated (GtkTreeView *view,
GtkTreePath *path,
GtkTreeViewColumn *col,
gpointer user_data)
{
GtkTreeModel *model;
GtkTreeIter iter;
g_print ("Row has been double-clicked. Removing row.\n");
model = gtk_tree_view_get_model(view);
if (!gtk_tree_model_get_iter(model, &amp;iter, path))
return; /* path describes a non-existing row - should not happen */
gtk_list_store_remove(GTK_LIST_STORE(model), &amp;iter);
}
void
create_treeview (void)
{
...
g_signal_connect(treeview, "row-activated", G_CALLBACK(onRowActivated), NULL);
...
}
</programlisting>
<para>
<emphasis>Note:</emphasis> <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkListStore.html#gtk-list-store-remove">
<literal>gtk_list_store_remove</literal></ulink> and
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeStore.html#gtk-tree-store-remove">
<literal>gtk_tree_store_remove</literal></ulink> both have slightly different
semantics in Gtk+-2.0 and Gtk+-2.2 and later. In Gtk+-2.0, both functions do
not return a value, while in later Gtk+ versions those functions return either
<literal>TRUE</literal> or <literal>FALSE</literal> to indicate whether the
iter given has been set to the next valid row (or invalidated if there is no
next row). This is important to keep in mind when writing code that is supposed
to work with all Gtk+-2.x versions. In that case you should just ignore the
value returned (as in the call above) and check the iter with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkListStore.html#gtk-list-store-iter-is-valid">
<literal>gtk_list_store_iter_is_valid</literal></ulink> if you need it.
</para>
<para>
If you want to remove the n-th row from a list (or the n-th child of a tree node),
you have two approaches: either you first create a <literal>GtkTreePath</literal>
that describes that row and then turn it into an iter and remove it; or you take
the iter of the parent node and use
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-nth-child">
<literal>gtk_tree_model_iter_nth_child</literal></ulink> (which will also work
for list stores if you use <literal>NULL</literal> as the parent iter. Of course
you could also start with the iter of the first top-level row, and then step-by-step
move it to the row you want, although that seems a rather awkward way of doing it.
</para>
<para>
The following code snippet will remove the n-th row of a list if it exists:
</para>
<programlisting role="C">
/******************************************************************
*
* list_store_remove_nth_row
*
* Removes the nth row of a list store if it exists.
*
* Returns TRUE on success or FALSE if the row does not exist.
*
******************************************************************/
gboolean
list_store_remove_nth_row (GtkListStore *store, gint n)
{
GtkTreeIter iter;
g_return_val_if_fail (GTK_IS_LIST_STORE(store), FALSE);
/* NULL means the parent is the virtual root node, so the
* n-th top-level element is returned in iter, which is
* the n-th row in a list store (as a list store only has
* top-level elements, and no children) */
if (gtk_tree_model_iter_nth_child(GTK_TREE_MODEL(store), &amp;iter, NULL, n))
{
gtk_list_store_remove(store, &amp;iter);
return TRUE;
}
return FALSE;
}
</programlisting>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-remove-many-rows">
<title>Removing Multiple Rows</title>
<para>
Removing multiple rows at once can be a bit tricky at times, and requires some thought on how to do this best. For
example, it is not possible to traverse a store with <literal>gtk_tree_model_foreach</literal>, check in the callback
function whether the given row should be removed and then just remove it by calling one of the stores' remove functions.
This will not work, because the model is changed from within the foreach loop, which might suddenly invalidate formerly
valid tree iters in the foreach function, and thus lead to unpredictable results.
</para>
<para>
You could traverse the store in a <literal>while</literal> loop of course, and call
<literal>gtk_list_store_remove</literal> or <literal>gtk_tree_store_remove</literal>
whenever you want to remove a row, and then just continue if the remove functions
returns <literal>TRUE</literal> (meaning that the iter is still valid and now points
to the row after the row that was removed). However, this approach will only work
with Gtk+-2.2 or later and will not work if you want your programs to compile
and work with Gtk+-2.0 as well, for the reasons outlined above (in Gtk+-2.0 the
remove functions did not set the passed iter to the next valid row). Also, while
this approach might be feasable for a list store, it gets a bit awkward for a
tree store.
</para>
<para>
Here is an example for an alternative approach to removing multiple rows
in one go (here we want to remove all rows from the store that contain
persons that have been born after 1980, but it could just as well be
all selected rows or some other criterion):
</para>
<programlisting role="C">
/******************************************************************
*
* Removing multiple rows in one go
*
******************************************************************/
...
gboolean
foreach_func (GtkTreeModel *model,
GtkTreePath *path,
GtkTreeIter *iter,
GList **rowref_list)
{
guint year_of_birth;
g_assert ( rowref_list != NULL );
gtk_tree_model_get (model, iter, COL_YEAR_BORN, &amp;year_of_birth, -1);
if ( year_of_birth &gt; 1980 )
{
GtkTreeRowReference *rowref;
rowref = gtk_tree_row_reference_new(model, path);
*rowref_list = g_list_append(*rowref_list, rowref);
}
return FALSE; /* do not stop walking the store, call us with next row */
}
void
remove_people_born_after_1980 (void)
{
GList *rr_list = NULL; /* list of GtkTreeRowReferences to remove */
GList *node;
gtk_tree_model_foreach(GTK_TREE_MODEL(store),
(GtkTreeModelForeachFunc) foreach_func,
&amp;rr_list);
for ( node = rr_list; node != NULL; node = node-&gt;next )
{
GtkTreePath *path;
path = gtk_tree_row_reference_get_path((GtkTreeRowReference*)node-&gt;data);
if (path)
{
GtkTreeIter iter;
if (gtk_tree_model_get_iter(GTK_TREE_MODEL(store), &amp;iter, path))
{
gtk_list_store_remove(store, &amp;iter);
}
/* FIXME/CHECK: Do we need to free the path here? */
}
}
g_list_foreach(rr_list, (GFunc) gtk_tree_row_reference_free, NULL);
g_list_free(rr_list);
}
...
</programlisting>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkListStore.html#gtk-list-store-clear">
<literal>gtk_list_store_clear</literal></ulink> and <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeStore.html#gtk-tree-store-clear">
<literal>gtk_tree_store_clear</literal></ulink> come in handy if you want to remove all rows.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-storing-gobjects">
<title>Storing GObjects (Pixbufs etc.)</title>
<para>
A special case are <literal>GObject</literal> types, like <literal>GDK_TYPE_PIXBUF</literal>,
that get stored in a list or tree store. The store will not make a copy of the object, rather
it will increase the object's refcount. The store will then unref the object again if it is
no longer needed (ie. a new object is stored in the old object's place, the current value
is replaced by NULL, the row is removed, or the store is destroyed).
</para>
<para>
From a developer perspective, this means that you need to <literal>g_object_unref</literal>
an object that you have just added to the store if you want the store to automatically dispose
of it when no longer needed. This is because on object creation, the object has an initial
refcount of 1, which is "your" refcount, and the object will only be destroyed when it
reaches a refcount of 0. Here is the life cycle of a pixbuf:
</para>
<programlisting role="C">
GtkListStore *list_store;
GtkTreeIter iter;
GdkPixbuf *pixbuf;
GError *error = NULL;
list_store = gtk_list_store_new (2, GDK_TYPE_PIXBUF, G_TYPE_STRING);
pixbuf = gdk_pixbuf_new_from_file(&quot;icon.png&quot;, &amp;error);
/* pixbuf has a refcount of 1 after creation */
if (error)
{
g_critical (&quot;Could not load pixbuf: %s\n&quot;, error->message);
g_error_free(error);
return;
}
gtk_list_store_append(list_store, &amp;iter);
gtk_list_store_set(list_store, &amp;iter, 0, pixbuf, 1, &quot;foo&quot;, -1);
/* pixbuf has a refcount of 2 now, as the list store has added its own reference */
g_object_unref(pixbuf);
/* pixbuf has a refcount of 1 now that we have released our initial reference */
/* we don't want an icon in that row any longer */
gtk_list_store_set(list_store, &amp;iter, 0, NULL, -1);
/* pixbuf has automatically been destroyed after its refcount has reached 0.
* The list store called g_object_unref() on the pixbuf when it replaced
* the object in the store with a new value (NULL). */
</programlisting>
<para>
Having learned how to add, manipulate, and retrieve data from a store, the next step is to get that data
displayed in a <literal>GtkTreeView</literal> widget.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treemodel-storing-structs">
<title>Storing Data Structures: of Pointers, GBoxed Types, and GObject (TODO)</title>
<para>
Unfinished chapter.
</para>
<!--
<para>
<emphasis>
This section is for advanced users. You might want to skip it
for now and come back to it later when you find yourself
needing to store C-type custom data structures of your own
in a tree model.
</emphasis>
</para>
<para>
<emphasis>
This section is also not really very refined and only a rough draft.
Its purpose is just to introduce some approaches that might not be
immediately obvious for someone not familiar with the API.
</emphasis>
</para>
<para>
If the data you want to display becomes more complex (or simply
just a lot), storing it into a list store or tree store using
a trizillion model columns is not always the most convenient
way. It quickly leads to bulky code and unnecessary overhead.
</para>
<para>
Also, you often have an object or item of data where you
only want to display <emphasis>some</emphasis> of the data
in the tree view and have a fair bit of data you need to keep
track of in addition. Storing all the data in the model is
inconvenient, and keeping two copies of the data around and
syncing the data in the model with the data in the structure
is also inconvenient, even more so if the data changes
regularly.
</para>
<para>
Consider a tree view that displays the download status of
various files, e.g. a web browser's download window. You
might want to display the following data for each download:
<itemizedlist>
<listitem><para>
Destination File Name or Path
</para></listitem>
<listitem><para>
Source URL
</para></listitem>
<listitem><para>
Size of Download
</para></listitem>
<listitem><para>
Download Status (Completed, Paused, Queued, Downloading, etc.)
</para></listitem>
<listitem><para>
Download Speed (if applicable)
</para></listitem>
<listitem><para>
Estimated Time Left
</para></listitem>
</itemizedlist>
</para>
<para>
An obvious solution is to keep track of a download in a structure,
something along the lines of
</para>
<programlisting role="C">
typedef struct _MyDownload MyDownload;
struct _MyDownload
{
gchar *dest_fn;
gchar *src_url;
guint status;
guint64 size;
guint64 transfered;
gfloat speed;
guint seconds_left;
... more variables for the download action itself ..
};
</programlisting>
<para>
Then you could have list store with a column of <literal>G_TYPE_POINTER</literal>
and just store a pointer to the structure there for each row. Instead of connecting
model columns to cell renderer properties via attributes (see below), you will have
to use cell data functions with this approach.
</para>
<para>
The main issue with storing struct pointers in a list store is that memory management
becomes a bit awkward. You have to make sure that you remove the pointer data and/or
whole row from the store when you free the structure. Equally, you need to free the
structure 'manually' when you remove the row and don't need it any longer. Nothing
that cannot be solved, yet still not exactly elegant either.
</para>
<para>
The advantage is of course that code that retrieves data from a row (e.g. a selected row)
becomes much cleaner, and that there is less overhead when retrieving data (like string
copies). Compare
</para>
<programlisting role="C">
void
treeview_on_row_activated (GtkTreeView *treeview,
GtkTreePath *path,
GtkTreeViewColumn *col,
gpointer data)
{
GtkTreeModel *model;
GtkTreeIter iter;
model = gtk_tree_view_get_model (treeview);
if (gtk_tree_model_get_iter (model, &amp;iter, path))
{
gchar *fn, *url;
guint status;
gtk_tree_model_get (model, &amp;iter,
COL_FILENAME, &amp;fn,
COL_URL, &amp;url,
COL_STATUS, &amp;status,
-1);
... do something with data on row double-click ....
g_free (fn);
g_free (url);
}
}
</programlisting>
<para>
with
</para>
<programlisting role="C">
void
treeview_on_row_activated (GtkTreeView *treeview,
GtkTreePath *path,
GtkTreeViewColumn *col,
gpointer data)
{
GtkTreeModel *model;
GtkTreeIter iter;
model = gtk_tree_view_get_model (treeview);
if (gtk_tree_model_get_iter (model, &amp;iter, path))
{
MyDownload *dl;
gtk_tree_model_get (model, &amp;iter, 0, &amp;dl, -1);
... do something with data on row double-click ....
}
}
</programlisting>
<para>
Now, It would be nice if one could use memory management
techniques like reference counting with one's custom
structures, and have the tree models make use of them
automatically, just like the tree models take care of
memory management for strings or for GObjects like GdkPixbuf.
</para>
<para>
The obvious way would be to derive MyDownload from GObject,
in which case it will be handled automatically by the models.
This requires a bit of a dive into the GObject system though
and makes things more complicated than they have to be.
</para>
<para>
The alternative is to register your own type as a GBoxed-derived
type with the GType system, and implement some simple refcounting
yourself. Some code snippets:
</para>
<programlisting role="C">
#define MY_TYPE_DOWNLOAD (my_download_get_type())
typedef struct _MyDownload MyDownload;
struct _MyDownload
{
gchar *dest_fn;
gchar *src_url;
guint status;
... more ...
gint refcount;
};
void
my_download_ref (MyDownload *dl)
{
g_return_if_fail (dl->refcount > 0);
dl->refcount += 1;
}
void
my_download_unref (MyDownload *dl)
{
g_return_if_fail (dl->refcount > 0);
dl->refcount -= 1;
if (dl->refcount == 0)
{
/* free structure content */
g_free (dl->dest_fn);
g_free (dl->src_url);
/* poison memory */
memset (dl, 0xFF, sizeof (MyDownload));
/* free structure itself */
g_free (dl);
}
}
static gpointer
my_download_copy_func (gpointer boxed)
{
my_download_ref ((MyDownload*) boxed);
return boxed;
}
static void
my_download_free_func (gpointer boxed)
{
/* for clarity */
my_download_unref ((MyDownload*) boxed);
}
GType
my_download_get_type (void)
{
static GType my_type = 0;
if (my_type == 0)
{
my_type = g_boxed_type_register_static ("MyDownload",
my_download_copy_func,
my_download_free_func);
}
return my_type;
}
MyDownload *
make_new_download (const gchar *from, const gchar *to)
{
MyDownload *dl;
dl = g_new0 (MyDownload, 1);
dl->src_url = g_strdup (from);
dl->dest_fn = g_strdup (to);
dl->status = 0;
dl->refcount = 1;
return dl;
}
</programlisting>
-->
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-treeview">
<title>Creating a Tree View</title>
<para>
In order to display data in a tree view widget, we need to create one
first, and we need to instruct it where to get the data to display
from.
</para>
<para>
A new tree view is created with:
</para>
<programlisting role="C">
GtkWidget *view;
view = gtk_tree_view_new();
</programlisting>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-connect-model">
<title>Connecting Tree View and Model</title>
<para>
Before we proceed to the next section where we display data on the screen,
we need connect our data store to the tree view, so it knows where to
get the data to display from. This is achieved with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-set-model">
<literal>gtk_tree_view_set_model</literal></ulink>, which will by itself
do very little. However, it is a prerequisite for what we do in the
following sections.
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-new-with-model">
<literal>gtk_tree_view_new_with_model</literal></ulink> is a convenience
function for the previous two.
</para>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-get-model">
<literal>gtk_tree_view_get_model</literal></ulink> will return the model that
is currently attached to a given tree view, which is particularly useful in
callbacks where you only get passed the tree view widget (after all, we do not
want to go down the road of global variables, which will inevitably lead to
the Dark Side, do we?).
</para>
<!-- ************************************************************** -->
<sect2 id="sec-treeview-connect-model-refcounting">
<title>Reference counting</title>
<para>
Tree models like <literal>GtkListStore</literal> and <literal>GtkTreeStore</literal>
are <literal>GObjects</literal> and have a reference count of 1 after creation. The
tree view will add its own reference to the model when you add the model with
<literal>gtk_tree_view_set_model</literal>, and will unref it again when you replace
the model with another model, unset the model by passing <literal>NULL</literal> as
a model, or when the tree view is destroyed.
<footnote><para>
'Reference counting' means that an object has a counter that can be
increased or decreased (ref-ed and unref-ed). If the counter is unref-ed to 0, the
object is automatically destroyed. This is useful, because other objects or
application programmers only have to think about whether <emphasis>they themselves</emphasis>
are still using that object or not, without knowing anything about others also using
it. The object is simply automatically destroyed when no one is using it any more.
</para></footnote>
</para>
<para>
This means that you need to take care of "your" reference yourself, otherwise the
model will not be destroyed properly when you disconnect it from the tree view, and
its memory will not be freed (which does not matter much if the same model is
connected to the tree view from application start to end). If you plan to use
the same model for a tree view for the whole duration of the application, you can
get rid of "your" reference right after you have connected the model to the
view - then the model will be destroyed automatically when the tree view is
destroyed (which will be automatically destroyed when the window it is in is
destroyed):
</para>
<programlisting role="C">
GtkListStore *liststore;
GtkWidget *view;
view = gtk_tree_view_new();
liststore = gtk_list_store_new(1, G_TYPE_STRING);
gtk_tree_view_set_model(GTK_TREE_VIEW(view), GTK_TREE_MODEL(liststore));
g_object_unref(liststore);
/* Now the model will be destroyed when the tree view is destroyed */
</programlisting>
</sect2>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-look">
<title>Tree View Look and Feel</title>
<para>
There are a couple of ways to influence the look and feel of the tree
view. You can hide or show column headers with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-set-headers-visible">
<literal>gtk_tree_view_set_headers_visible</literal></ulink>, and set
them clickable or not with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-set-headers-clickable">
<literal>gtk_tree_view_set_headers_clickable</literal></ulink> (which
will be done automatically for you if you enable sorting).
</para>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-set-rules-hint">
<literal>gtk_tree_view_set_rules_hint</literal></ulink> will enable or disable
rules in the tree view.
<footnote>
<para>
'Rules' means that every second line of the tree view has a
shaded background, which makes it easier to see which cell
belongs to which row in tree views that have a lot of columns.
</para>
</footnote>
As the function name implies, this setting is only a
hint; in the end it depends on the active Gtk+ theme engine if the tree view
shows ruled lines or not. Users seem to have strong feelings about rules
in tree views, so it is probably a good idea to provide an option somewhere
to disable rule hinting if you set it on tree views (but then, people also
seem to have strong feelings about options abundance and 'sensible' default
options, so whatever you do will probably upset someone at some point).
</para>
<para>
The expander column can be set with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-set-expander-column">
<literal>gtk_tree_view_set_expander_column</literal></ulink>. This is the column where
child elements are indented with respect to their parents, and where rows with children
have an 'expander' arrow with which a node's children can be collapsed (hidden) or
expanded (shown). By default, this is the first column.
</para>
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-treeviewcol-renderer">
<title>Mapping Data to the Screen: GtkTreeViewColumn and GtkCellRenderer</title>
<para>
As outlined above, tree view columns represent the visible columns on the
screen that have a column header with a column name and can be resized or
sorted. A tree view is made up of tree view columns, and you need at least
one tree view column in order to display something in the tree view. Tree
view columns, however, do not display anything by themselves, this is done
by specialised <literal>GtkCellRenderer</literal> objects. Cell renderers
are packed into tree view columns much like widgets are packed into
<literal>GtkHBoxes</literal>.
</para>
<para>
Here is a diagram (courtesy of Owen Taylor) that pictures the relationship
between tree view columns and cell renderers:
</para>
<figure id="sec-treeviewcol-renderer-diagram">
<title>Cell Renderer Properties</title>
<screenshot>
<mediaobject>
<imageobject>
<imagedata fileref="images/tree-view-column.png" format="PNG" />
</imageobject>
<imageobject>
<imagedata fileref="images/tree-view-column.eps" format="EPS" />
</imageobject>
</mediaobject>
</screenshot>
</figure>
<para>
In the above diagram, both 'Country' and 'Representative' are tree view columns,
where the 'Country' and 'Representative' labels are the column headers.
The 'Country' column contains two cell renderers, one to display the flag icons,
and one to display the country name. The 'Representative' column only contains
one cell renderer to display the representative's name.
</para>
<!-- ************************************************************** -->
<sect1 id="sec-renderer">
<title>Cell Renderers</title>
<para>
Cell renderers are objects that are responsible for the actual rendering
of data within a <literal>GtkTreeViewColumn</literal>. They are basically
just GObjects (ie. not widgets) that have certain properties, and those
properties determine how a single cell is drawn.
</para>
<para>
In order to draw cells in different rows with different content,
a cell renderer's properties need to be set accordingly for each
single row/cell to render. This is done either via
<link linkend="sec-treeview-col-attributes">attributes</link> or
<link linkend="sec-treeview-col-celldatafunc">cell data functions</link>
(see below). If you set up attributes,
you tell Gtk which model column contains the data from which a
property should be set before rendering a certain row. Then the
properties of a cell renderer are set automatically according to
the data in the model before each row is rendered. Alternatively,
you can set up cell data functions, which are called for each
row to be rendererd, so that you can manually set the properties
of the cell renderer before it is rendered. Both approaches can
be used at the same time as well. Lastly, you can set a cell
renderer property when you create the cell renderer. That way it
will be used for all rows/cells to be rendered (unless it is
changed later of course).
</para>
<para>
Different cell renderers exist for different purposes:
</para>
<itemizedlist>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkCellRendererText.html">
<literal>GtkCellRendererText</literal></ulink> renders strings or numbers or
boolean values as text ("Joe", "99.32", "true")
</simpara>
</listitem>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkCellRendererPixbuf.html">
<literal>GtkCellRendererPixbuf</literal></ulink> is used to display images;
either user-defined images, or one of the stock icons that come with Gtk+.
</simpara>
</listitem>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkCellRendererToggle.html">
<literal>GtkCellRendererToggle</literal></ulink> displays a boolean value in
form of a check box or as a radio button.
</simpara>
</listitem>
<listitem>
<simpara>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkCellEditable.html">
<literal>GtkCellEditable</literal></ulink> is a special cell that
implements editable cells (ie. GtkEntry or GtkSpinbutton in a treeview).
This is not a cell renderer! If you want to have editable text cells, use
<literal>GtkCellRendererText</literal> and make sure the "editable" property
is set. <literal>GtkCellEditable</literal> is only used by implementations
of editable cells and widgets that can be inside of editable cells.
You are unlikely to ever need it.
</simpara>
</listitem>
</itemizedlist>
<para>
Contrary to what one may think, a cell renderer does not render just one
single cell, but is responsible for rendering part or whole of a tree
view column for each single row. It basically starts in the first row
and renders its part of the column there. Then it proceeds to the next
row and renders its part of the column there again. And so on.
</para>
<para>
How does a cell renderer know what to render? A cell renderer object
has certain 'properties' that are documented in the
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/TreeWidgetObjects.html">
API reference</ulink> (just like most other objects, and widgets).
These properties determine what the cell renderer is going to
render and how it is going to be rendered. Whenever the cell
renderer is called upon to render a certain cell, it looks at
its properties and renders the cell accordingly. This means that
whenever you set a property or change a property of the cell
renderer, this will affect all rows that are rendered after the
change, until you change the property again.
</para>
<para>
Here is a diagram (courtesy of Owen Taylor) that tries to show what is going
on when rows are rendered:
</para>
<figure id="sec-treeviewcol-diagram">
<title>GtkTreeViewColumns and GtkCellRenderers</title>
<screenshot>
<mediaobject>
<imageobject>
<imagedata fileref="images/cell-renderer-properties.png" format="PNG" />
</imageobject>
<imageobject>
<imagedata fileref="images/cell-renderer-properties.eps" format="EPS" />
</imageobject>
</mediaobject>
</screenshot>
</figure>
<para>
The above diagram shows the process when attributes are used. In the example, a
text cell renderer's <literal>"text"</literal> property has been linked to the
first model column. The <literal>"text"</literal> property contains the string
to be rendered. The <literal>"foreground"</literal> property, which contains the
colour of the text to be shown, has been linked to the second model column. Finally,
the <literal>"strikethrough"</literal> property, which determines whether the text
should be with a horizontal line that strikes through the text, has been connected to
the third model column (of type <literal>G_TYPE_BOOLEAN</literal>).
</para>
<para>
With this setup, the cell renderer's properties are 'loaded' from the model before
each cell is rendered.
</para>
<para>
Here is a silly and utterly useless little example that demonstrates
this behaviour, and introduces some of the most commonly used
properties of <literal>GtkCellRendererText</literal>:
</para>
<programlisting role="C">
#include &lt;gtk/gtk.h&gt;
enum
{
COL_FIRST_NAME = 0,
COL_LAST_NAME,
NUM_COLS
} ;
static GtkTreeModel *
create_and_fill_model (void)
{
GtkTreeStore *treestore;
GtkTreeIter toplevel, child;
treestore = gtk_tree_store_new(NUM_COLS, G_TYPE_STRING, G_TYPE_STRING);
/* Append a top level row and leave it empty */
gtk_tree_store_append(treestore, &amp;toplevel, NULL);
/* Append a second top level row, and fill it with some data */
gtk_tree_store_append(treestore, &amp;toplevel, NULL);
gtk_tree_store_set(treestore, &amp;toplevel,
COL_FIRST_NAME, "Joe",
COL_LAST_NAME, "Average",
-1);
/* Append a child to the second top level row, and fill in some data */
gtk_tree_store_append(treestore, &amp;child, &amp;toplevel);
gtk_tree_store_set(treestore, &amp;child,
COL_FIRST_NAME, "Jane",
COL_LAST_NAME, "Average",
-1);
return GTK_TREE_MODEL(treestore);
}
static GtkWidget *
create_view_and_model (void)
{
GtkTreeViewColumn *col;
GtkCellRenderer *renderer;
GtkWidget *view;
GtkTreeModel *model;
view = gtk_tree_view_new();
/* --- Column #1 --- */
col = gtk_tree_view_column_new();
gtk_tree_view_column_set_title(col, "First Name");
/* pack tree view column into tree view */
gtk_tree_view_append_column(GTK_TREE_VIEW(view), col);
renderer = gtk_cell_renderer_text_new();
/* pack cell renderer into tree view column */
gtk_tree_view_column_pack_start(col, renderer, TRUE);
/* set 'text' property of the cell renderer */
g_object_set(renderer, "text", "Boooo!", NULL);
/* --- Column #2 --- */
col = gtk_tree_view_column_new();
gtk_tree_view_column_set_title(col, "Last Name");
/* pack tree view column into tree view */
gtk_tree_view_append_column(GTK_TREE_VIEW(view), col);
renderer = gtk_cell_renderer_text_new();
/* pack cell renderer into tree view column */
gtk_tree_view_column_pack_start(col, renderer, TRUE);
/* set 'cell-background' property of the cell renderer */
g_object_set(renderer,
"cell-background", "Orange",
"cell-background-set", TRUE,
NULL);
model = create_and_fill_model();
gtk_tree_view_set_model(GTK_TREE_VIEW(view), model);
g_object_unref(model); /* destroy model automatically with view */
gtk_tree_selection_set_mode(gtk_tree_view_get_selection(GTK_TREE_VIEW(view)),
GTK_SELECTION_NONE);
return view;
}
int
main (int argc, char **argv)
{
GtkWidget *window;
GtkWidget *view;
gtk_init(&amp;argc, &amp;argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
g_signal_connect(window, "delete_event", gtk_main_quit, NULL); /* dirty */
view = create_view_and_model();
gtk_container_add(GTK_CONTAINER(window), view);
gtk_widget_show_all(window);
gtk_main();
return 0;
}
</programlisting>
<para>
The above code should produce something looking like this:
</para>
<figure id="sec-renderer-sshot">
<title>Persistent Cell Renderer Properties</title>
<screenshot>
<mediaobject>
<imageobject>
<imagedata fileref="images/renderer.png" format="PNG" />
</imageobject>
<imageobject>
<imagedata fileref="images/renderer.eps" format="EPS" />
</imageobject>
</mediaobject>
</screenshot>
</figure>
<para>
It looks like the tree view display is partly correct and partly incomplete.
On the one hand the tree view renders the correct number of rows (note
how there is no orange on the right after row 3), and it displays the
hierarchy correctly (on the left), but it does not display any of the
data that we have stored in the model. This is because we have made no
connection between what the cell renderers should render and the data
in the model. We have simply set some cell renderer properties on
start-up, and the cell renderers adhere to those set properties meticulously.
</para>
<para>
There are two different ways to connect cell renderers to data in the model:
<link linkend="sec-treeview-col-attributes">attributes</link> and
<link linkend="sec-treeview-col-celldatafunc">cell data functions</link>.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-col-attributes">
<title>Attributes</title>
<para>
An attribute is a connection between a cell renderer property and a
field/column in the model. Whenever a cell is to be rendered, a cell renderer
property will be set to the values of the specified model column of the row
that is to be rendered. It is very important that the column's data type is
the same type that a property takes according to the API reference manual.
Here is some code to look at:
</para>
<programlisting role="C">
...
col = gtk_tree_view_column_new();
renderer = gtk_cell_renderer_text_new();
gtk_tree_view_column_pack_start(col, renderer, TRUE);
gtk_tree_view_column_add_attribute(col, renderer, "text", COL_FIRST_NAME);
...
</programlisting>
<para>
This means that the text cell renderer property <literal>"text"</literal>
will be set to the string in model column <literal>COL_FIRST_NAME</literal>
of each row to be drawn. It is important to internalise the difference
between <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeViewColumn.html#gtk-tree-view-column-add-attribute">
<literal>gtk_tree_view_column_add_attribute</literal></ulink> and
<literal>g_object_set</literal>: <literal>g_object_set</literal> sets
a property to a certain <emphasis>value</emphasis>, while
<literal>gtk_tree_view_column_add_attribute</literal> sets a property
to whatever is in the specified _model column_ at the time of rendering.
</para>
<para>
Again, when setting attributes it is very important that the data type
stored in a model column is the same as the data type that a property
requires as argument. Check the API reference manual to see the data type
that is required for each property. When reading through the example a bit
further above, you might have noticed that we set the <literal>"cell-background"</literal>
property of a <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkCellRendererText.html">
<literal>GtkCellRendererText</literal></ulink>, even though the
API documentation does not list such a property. We can do this, because
<literal>GtkCellRendererText</literal> is derived from
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkCellRenderer.html">
<literal>GtkCellRenderer</literal></ulink>, which does in fact
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkCellRenderer.html#GtkCellRenderer--cell-background">
have</ulink> such a property. Derived classes inherit the properties of their
parents. This is the same as with widgets that you can cast into one of their
ancestor classes. The API reference has an
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/ch01.html">object hierarchy</ulink>
that shows you which classes a widget or some other object is derived from.
</para>
<para>
There are two more noteworthy things about <literal>GtkCellRenderer</literal>
properties: one is that sometimes there are different properties which do
the same, but take different arguments, such as the <literal>"foreground"</literal>
and <literal>"foreground-gdk"</literal> properties of <literal>GtkCellRendererText</literal>
(which specify the text colour). The <literal>"foreground"</literal> property take a colour in string form, such as "Orange" or
"CornflowerBlue", whereas <literal>"foreground-gdk"</literal> takes a
<ulink url="http://developer.gnome.org/doc/API/2.0/gdk/gdk-Colormaps-and-Colors.html#GdkColor">GdkColor</ulink>
argument. It is up to you to
decide which one to use - the effect will be the same. The other thing worth mentioning is
that most properties have a <literal>"foo-set"</literal> property taking a boolean value
as argument, such as <literal>"foreground-set"</literal>. This is useful when you want
to have a certain setting have an effect or not. If you set the <literal>"foreground"</literal>
property, but set <literal>"foreground-set"</literal> to <literal>FALSE</literal>, then your
foreground color setting will be disregarded. This is useful in cell data functions (see
below), or, for example, if you want set the foreground colour to a certain value at
start-up, but only want this to be in effect in some columns, but not in others (in which
case you could just connect the <literal>"foreground-set"</literal> property to a model
column of type <literal>G_TYPE_BOOLEAN</literal> with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeViewColumn.html#gtk-tree-view-column-add-attribute">
<literal>gtk_tree_view_column_add_attribute</literal></ulink>.
</para>
<para>
Setting column attributes is the most straight-forward way to get your model data to be
displayed. This is usually used whenever you want the data in the model to be displayed
exactly as it is in the model.
</para>
<para>
Another way to get your model data displayed on the screen is to set up cell data functions.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-col-celldatafunc">
<title>Cell Data Functions</title>
<para>
A cell data function is a function that is called for a specific cell renderer
for each single row before that row is rendered. It gives you maximum control
over what exactly is going to be rendered, as you can set the cell renderer's
properties just like you want to have them. Remember not only to
<emphasis>set</emphasis> a property if you want it to be active, but also to
<emphasis>unset</emphasis> a property if it should not be active (and it might
have been set in the previous row).
</para>
<para>
Cell data functions are often used if you want more fine-grained control over
what is to be displayed, or if the standard way to display something is not
quite like you want it to be. A case in point are floating point numbers. If
you want floating point numbers to be displayed in a certain way, say with only
one digit after the colon/comma, then you need to use a cell data function.
Use <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeViewColumn.html#gtk-tree-view-column-set-cell-data-func">
<literal>gtk_tree_view_column_set_cell_data_func</literal></ulink> to set up a
cell data function for a particular cell renderer. Here is an example:
</para>
<programlisting role="C">
enum
{
COLUMN_NAME = 0,
COLUMN_AGE_FLOAT,
NUM_COLS
};
...
static void
age_cell_data_function (GtkTreeViewColumn *col,
GtkCellRenderer *renderer,
GtkTreeModel *model,
GtkTreeIter *iter,
gpointer user_data)
{
gfloat age;
gchar buf[20];
gtk_tree_model_get(model, iter, COLUMN_AGE_FLOAT, &amp;age, -1);
g_snprintf(buf, sizeof(buf), "%.1f", age);
g_object_set(renderer, "text", buf, NULL);
}
...
liststore = gtk_list_store_new(NUM_COLS, G_TYPE_STRING, G_TYPE_FLOAT);
col = gtk_tree_view_column_new();
cell = gtk_cell_renderer_text_new();
gtk_tree_view_column_pack_start(col, cell, TRUE);
gtk_tree_view_column_set_cell_data_func(col, cell, age_cell_data_func, NULL, NULL);
...
</programlisting>
<para>
for each row to be rendered by this particular cell renderer, the cell data
function is going to be called, which then retrieves the float from the model,
and turns it into a string where the float has only one digit after the
colon/comma, and renders that with the text cell renderer.
</para>
<para>
This is only a simple example, you can make cell data functions a lot more
complicated if you want to. As always, there is a trade-off to keep in mind
though. Your cell data function is going to be called every single time a
cell in that (renderer) column is going to be rendered. Go and check how
often this function is called in your program if you ever use one. If you
do time-consuming operations within a cell data function, things are not
going to be fast, especially if you have a lot of rows. The alternative
in this case would have been to make an additional column
COLUMN_AGE_FLOAT_STRING of type <literal>G_TYPE_STRING</literal>, and to set
the float in string form whenever you set the float itself in a row, and then
hook up the string column to a text cell renderer using attributes. This way
the float to string conversion would only need to be done once. This is a cpu
cycles / memory trade-off, and it depends on your particular case which one
is more suitable. Things you should probably not do is to convert long strings
into UTF8 format in a cell data function, for example.
</para>
<para>
You might notice that your cell data function is called at times even for rows
that are not visible at the moment. This is because the tree view needs to know
its total height, and in order to calculate this it needs to know the height of
each and every single row, and it can only know that by having it measured, which
is going to be slow when you have a lot of rows with different heights (if your
rows all have the same height, there should not be any visible delay though).
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-celltext-types">
<title>GtkCellRendererText and Integer, Boolean and Float Types</title>
<para>
It has been said before that, when using attributes to connect data from
the model to a cell renderer property, the data in the model column
specified in <literal>gtk_tree_view_column_add_attribute</literal> must
always be of the same type as the data type that the property requires.
</para>
<para>
This is usually true, but there is an exception: if you use
<literal>gtk_tree_view_column_add_attribute</literal> to connect
a text cell renderer's <literal>"text"</literal> property to a
model column, the model column does not need to be of
<literal>G_TYPE_STRING</literal>, it can also be one of most
other fundamental GLib types, e.g.
<literal>G_TYPE_BOOLEAN</literal>,
<literal>G_TYPE_INT</literal>,
<literal>G_TYPE_UINT</literal>,
<literal>G_TYPE_LONG</literal>,
<literal>G_TYPE_ULONG</literal>,
<literal>G_TYPE_INT64</literal>,
<literal>G_TYPE_UINT64</literal>,
<literal>G_TYPE_FLOAT</literal>, or
<literal>G_TYPE_DOUBLE</literal>. The text cell renderer
will automatically display the values of these types
correctly in the tree view. For example:
</para>
<programlisting role="C">
enum
{
COL_NAME = 0,
COL_YEAR_BORN,
NUM_COLS
};
liststore = gtk_list_store_new(NUM_COLS, G_TYPE_STRING, G_TYPE_UINT);
...
cell = gtk_cell_renderer_text_new();
col = gtk_tree_view_column_new();
gtk_tree_view_column_add_attribute(col, cell, "text", COL_YEAR_BORN);
...
</programlisting>
<para>
Even though the <literal>"text"</literal> property would require a
string value, we use a model column of an integer type when setting
attributes. The integer will then automatically be converted into
a string before the cell renderer property is set
<footnote><para>
For those interested, the conversion actually takes place within
<literal>g_object_set_property</literal>. Before a certain cell is
rendered, the tree view column will call <literal>gtk_tree_model_get_value</literal>
to set the cell renderer properties according to values stored in
the tree model (if any are mapped via <literal>gtk_tree_view_column_add_attribute</literal>
or one of the convenience functions that do the same thing), and then
pass on the <literal>GValue</literal> retrieved to
<literal>g_object_set_property</literal>.
</para></footnote>.
</para>
<para>
If you are using a floating point type, ie. <literal>G_TYPE_FLOAT</literal>
or <literal>G_TYPE_DOUBLE</literal>, there is no way to tell the text cell
renderer how many digits after the floating point (or comma) should be
rendered. If you only want a certain amount of digits after the point/comma,
you will need to use a <link linkend="sec-treeview-col-celldatafunc">cell data function</link>.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-col-utf8-pango">
<title>GtkCellRendererText, UTF8, and pango markup</title>
<para>
All text used in Gtk+-2.0 widgets needs to be in UTF8 encoding, and
<literal>GtkCellRendererText</literal> is no exception. Text in plain
ASCII is automatically valid UTF8, but as soon as you have special
characters that do not exist in plain ASCII (usually characters that
are not used in the English language alphabet), they need to be in
UTF8 encoding. There are many different character encodings that all
specify different ways to tell the computer which character is meant.
Gtk+-2.0 uses UTF8, and whenever you have text that is in a different
encoding, you need to convert it to UTF8 encoding first, using one of the GLib
<ulink url="http://developer.gnome.org/doc/API/2.0/glib/glib-Character-Set-Conversion.html">
<literal>g_convert</literal></ulink> family of functions. If you only
use text input from other Gtk+ widgets, you are on the safe side, as
they will return all text in UTF8 as well.
</para>
<para>
However, if you use 'external' sources of text input, then you
must convert that text from the text's encoding (or the user's locale) to UTF8,
or it will not be rendered correctly (either not at all, or it will be cut off
after the first invalid character). Filenames are especially hard, because there
is no indication whatsoever what character encoding a filename is in (it might
have been created when the user was using a different locale, so filename encoding
is basically unreliable and broken). You may want to convert to UTF8 with fallback
characters in that case. You can check whether a string is valid UTF8 with
<ulink url="http://developer.gnome.org/doc/API/2.0/glib/glib-Unicode-Manipulation.html#g-utf8-validate">
<literal>g_utf8_validate</literal></ulink>. You should, in this author's opinion
at least, put these checks into your code at crucial places wherever it is
not affecting performance, especially if you are an English-speaking programmer
that has little experience with non-English locales. It will make it easier for
others and yourself to spot problems with non-English locales later on.
</para>
<para>
In addition to the "text" property, GtkCellRendererText also has a "markup"
property that takes text with <ulink url="http://developer.gnome.org/doc/API/2.0/pango/PangoMarkupFormat.html">
pango markup</ulink> as input. Pango markup allows you to place special
tags into a text string that affect the style the text is rendered (see the pango
documentation). Basically you can achieve everything you can achieve with the other
properties also with pango markup (only that using properties is more efficient and
less messy). Pango markup has one distinct advantage though that you cannot achieve
with text cell renderer properties: with pango markup, you can change the text style
in the middle of the text, so you could, for example, render one part of a text string
in bold print, and the rest of the text in normal. Here is an example of a string with
pango markup:
</para>
<para><literal>
"You can have text in &lt;b&gt;bold&lt;/b&gt; or in a &lt;span color=&apos;Orange&apos;&gt;different color&lt;/span&gt;"
</literal></para>
<para>
When using the <literal>"markup"</literal> property, you need to take into account
that the <literal>"markup"</literal> and <literal>"text"</literal> properties do
not seem to be mutually exclusive (I suppose this could be called a bug).
In other words: whenever you set <literal>"markup"</literal> (and have used the
<literal>"text"</literal> property before), set the <literal>"text"</literal>
property to NULL, and vice versa. Example:
</para>
<programlisting role="C">
...
void
foo_cell_data_function ( ... )
{
...
if (foo-&gt;is_important)
g_object_set(renderer, "markup", "&lt;b&gt;important&lt;/b&gt;", "text", NULL, NULL);
else
g_object_set(renderer, "markup", NULL, "text", "not important", NULL);
...
}
...
</programlisting>
<para>
Another thing to keep in mind when using pango markup text is that you might need to escape
text if you construct strings with pango markup on the fly using random input data. For example:
</para>
<programlisting role="C">
...
void
foo_cell_data_function ( ... )
{
gchar *markuptxt;
...
/* This might be problematic if artist_string or title_string
* contain markup characters/entities: */
markuptxt = g_strdup_printf("&lt;b&gt;%s&lt;/b&gt; - &lt;i&gt;%s&lt;/i&gt;",
artist_string, title_string);
...
g_object_set(renderer, "markup", markuptxt, "text", NULL, NULL);
...
g_free(markuptxt);
}
...
</programlisting>
<para>
The above example will not work if artist_string is "Simon &amp; Garfunkel" for example, because the &amp;
character is one of the characters that is special. They need to be escaped, so that pango knows that they
do not refer to any pango markup, but are just characters. In this case the string would need to be
"Simon &amp;amp; Garfunkel" in order to make sense in between the pango markup in which it is going to be
pasted. You can escape a string with <ulink url="http://developer.gnome.org/doc/API/2.0/glib/glib-Simple-XML-Subset-Parser.html#g-markup-escape-text">
<literal>g_markup_escape</literal></ulink> (and you will need to free the
resulting newly-allocated string again with <literal>g_free</literal>).
</para>
<para>
It is possible to combine both pango markup and text cell renderer properties. Both will be 'added' together
to render the string in question, only that the text cell renderer properties will be applied to the whole
string. If you set the <literal>"markup"</literal> property to normal text without any pango markup,
it will render as normal text just as if you had used the <literal>"text"</literal> property. However,
as opposed to the <literal>"text"</literal> property, special characters in the <literal>"markup"</literal>
property text would still need to be escaped, even if you do not use pango markup in the text.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-col-example">
<title>A Working Example</title>
<para>
Here is our example from the very beginning again (with an additional column though),
only that the contents of the model are rendered properly on the screen this time.
Both attributes and a cell data function are used for demonstration purposes.
</para>
<programlisting role="C">
#include &lt;gtk/gtk.h&gt;
enum
{
COL_FIRST_NAME = 0,
COL_LAST_NAME,
COL_YEAR_BORN,
NUM_COLS
} ;
static GtkTreeModel *
create_and_fill_model (void)
{
GtkTreeStore *treestore;
GtkTreeIter toplevel, child;
treestore = gtk_tree_store_new(NUM_COLS,
G_TYPE_STRING,
G_TYPE_STRING,
G_TYPE_UINT);
/* Append a top level row and leave it empty */
gtk_tree_store_append(treestore, &amp;toplevel, NULL);
gtk_tree_store_set(treestore, &amp;toplevel,
COL_FIRST_NAME, "Maria",
COL_LAST_NAME, "Incognito",
-1);
/* Append a second top level row, and fill it with some data */
gtk_tree_store_append(treestore, &amp;toplevel, NULL);
gtk_tree_store_set(treestore, &amp;toplevel,
COL_FIRST_NAME, "Jane",
COL_LAST_NAME, "Average",
COL_YEAR_BORN, (guint) 1962,
-1);
/* Append a child to the second top level row, and fill in some data */
gtk_tree_store_append(treestore, &amp;child, &amp;toplevel);
gtk_tree_store_set(treestore, &amp;child,
COL_FIRST_NAME, "Janinita",
COL_LAST_NAME, "Average",
COL_YEAR_BORN, (guint) 1985,
-1);
return GTK_TREE_MODEL(treestore);
}
void
age_cell_data_func (GtkTreeViewColumn *col,
GtkCellRenderer *renderer,
GtkTreeModel *model,
GtkTreeIter *iter,
gpointer user_data)
{
guint year_born;
guint year_now = 2003; /* to save code not relevant for the example */
gchar buf[64];
gtk_tree_model_get(model, iter, COL_YEAR_BORN, &amp;year_born, -1);
if (year_born &lt;= year_now &amp;&amp; year_born &gt; 0)
{
guint age = year_now - year_born;
g_snprintf(buf, sizeof(buf), "%u years old", age);
g_object_set(renderer, "foreground-set", FALSE, NULL); /* print this normal */
}
else
{
g_snprintf(buf, sizeof(buf), "age unknown");
/* make red */
g_object_set(renderer, "foreground", "Red", "foreground-set", TRUE, NULL);
}
g_object_set(renderer, "text", buf, NULL);
}
static GtkWidget *
create_view_and_model (void)
{
GtkTreeViewColumn *col;
GtkCellRenderer *renderer;
GtkWidget *view;
GtkTreeModel *model;
view = gtk_tree_view_new();
/* --- Column #1 --- */
col = gtk_tree_view_column_new();
gtk_tree_view_column_set_title(col, "First Name");
/* pack tree view column into tree view */
gtk_tree_view_append_column(GTK_TREE_VIEW(view), col);
renderer = gtk_cell_renderer_text_new();
/* pack cell renderer into tree view column */
gtk_tree_view_column_pack_start(col, renderer, TRUE);
/* connect 'text' property of the cell renderer to
* model column that contains the first name */
gtk_tree_view_column_add_attribute(col, renderer, "text", COL_FIRST_NAME);
/* --- Column #2 --- */
col = gtk_tree_view_column_new();
gtk_tree_view_column_set_title(col, "Last Name");
/* pack tree view column into tree view */
gtk_tree_view_append_column(GTK_TREE_VIEW(view), col);
renderer = gtk_cell_renderer_text_new();
/* pack cell renderer into tree view column */
gtk_tree_view_column_pack_start(col, renderer, TRUE);
/* connect 'text' property of the cell renderer to
* model column that contains the last name */
gtk_tree_view_column_add_attribute(col, renderer, "text", COL_LAST_NAME);
/* set 'weight' property of the cell renderer to
* bold print (we want all last names in bold) */
g_object_set(renderer,
"weight", PANGO_WEIGHT_BOLD,
"weight-set", TRUE,
NULL);
/* --- Column #3 --- */
col = gtk_tree_view_column_new();
gtk_tree_view_column_set_title(col, "Age");
/* pack tree view column into tree view */
gtk_tree_view_append_column(GTK_TREE_VIEW(view), col);
renderer = gtk_cell_renderer_text_new();
/* pack cell renderer into tree view column */
gtk_tree_view_column_pack_start(col, renderer, TRUE);
/* connect a cell data function */
gtk_tree_view_column_set_cell_data_func(col, renderer, age_cell_data_func, NULL, NULL);
model = create_and_fill_model();
gtk_tree_view_set_model(GTK_TREE_VIEW(view), model);
g_object_unref(model); /* destroy model automatically with view */
gtk_tree_selection_set_mode(gtk_tree_view_get_selection(GTK_TREE_VIEW(view)),
GTK_SELECTION_NONE);
return view;
}
int
main (int argc, char **argv)
{
GtkWidget *window;
GtkWidget *view;
gtk_init(&amp;argc, &amp;argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
g_signal_connect(window, "delete_event", gtk_main_quit, NULL); /* dirty */
view = create_view_and_model();
gtk_container_add(GTK_CONTAINER(window), view);
gtk_widget_show_all(window);
gtk_main();
return 0;
}
</programlisting>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-col-whole-row">
<title>How to Make a Whole Row Bold or Coloured</title>
<para>
This seems to be a frequently asked question, so it is worth mentioning it here. You
have the two approaches mentioned above: either you use cell data functions, and check
in each whether a particular row should be highlighted in a particular way (bold, coloured, whatever),
and then set the renderer properties accordingly (and unset them if you want that row to look normal),
or you use attributes. Cell data functions are most likely not the right choice in this case though.
</para>
<para>
If you only want every second line to have a gray background to make it easier
for the user to see which data belongs to which line in wide tree views, then
you do not have to bother with the stuff mentioned here. Instead just set the
rules hint on the tree view as described in the <link linkend="sec-treeview-look">
here</link>, and everything will be done automatically, in colours that conform
to the chosen theme even (unless the theme disables rule hints, that is).
</para>
<para>
Otherwise, the most suitable approach for most cases is that you add two columns
to your model, one for the property itself (e.g. a column COL_ROW_COLOR
of type <literal>G_TYPE_STRING</literal>), and one for the boolean flag
of the property (e.g. a column COL_ROW_COLOR_SET of type
<literal>G_TYPE_BOOLEAN</literal>). You would then connect these columns
with the <literal>"foreground"</literal> and <literal>"foreground-set"</literal>
properties of each renderer. Now, whenever you set a row's COL_ROW_COLOR
field to a colour, and set that row's COL_ROW_COLOR_SET field to <literal>TRUE</literal>,
then this column will be rendered in the colour of your choice. If you
only want either the default text colour or one special other colour,
you could even achieve the same thing with just one extra model column:
in this case you could just set all renderer's <literal>"foreground"</literal>
property to whatever special color you want, and only connect the COL_ROW_COLOR_SET
column to all renderer's <literal>"foreground-set"</literal> property using
attributes. This works similar with any other attribute, only that you need to adjust
the data type for the property of course (e.g. <literal>"weight"</literal> would take a
<literal>G_TYPE_INT</literal>, in form of a <literal>PANGO_WEIGHT_FOO</literal>
define in this case).
</para>
<para>
As a general rule, you should not change the text colour or the background
colour of a cell unless you have a really good reason for it.
To <ulink url="http://ometer.com/gtk-colors.html">quote</ulink> Havoc
Pennington: <quote>Because colors in GTK+ represent a theme the user has chosen, you should never
set colors purely for aesthetic reasons. If users don't like GTK+ gray, they can change it themselves
to their favorite shade of orange.</quote>
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-treeview-col-pixbufs">
<title>How to Pack Icons into the Tree View</title>
<para>
So far we have only put text in the tree view. While everything you need
to know to display icons (in the form of <literal>GdkPixbuf</literal>s)
has been introduced in the previous sections, a short example might help
to make things clearer. The following code will pack an icon and some
text into the same tree view column:
</para>
<programlisting role="C">
enum
{
COL_ICON = 0,
COL_TEXT,
NUM_COLS
};
GtkListStore *
create_liststore(void)
{
GtkListStore *store;
GtkTreeIter iter;
GdkPixbuf *icon;
GError *error = NULL;
store = gtk_list_store_new(2, GDK_TYPE_PIXBUF, G_TYPE_STRING);
icon = gdk_pixbuf_new_from_file("icon.png", &amp;error);
if (error)
{
g_warning ("Could not load icon: %s\n", error->message);
g_error_free(error);
error = NULL;
}
gtk_list_store_append(store, &amp;iter);
gtk_list_store_set(store, &amp;iter,
COL_ICON, icon,
COL_TEXT, "example",
-1);
return store;
}
GtkWidget *
create_treeview(void)
{
GtkTreeModel *model;
GtkTreeViewColumn *col;
GtkCellRenderer *renderer;
GtkWidget *view;
model = GTK_TREE_MODEL(create_liststore());
view = gtk_tree_view_new_with_model(model);
col = gtk_tree_view_column_new();
gtk_tree_view_column_set_title(col, "Title");
renderer = gtk_cell_renderer_pixbuf_new();
gtk_tree_view_column_pack_start(col, renderer, FALSE);
gtk_tree_view_column_set_attributes(col, renderer,
"pixbuf", COL_ICON,
NULL);
renderer = gtk_cell_renderer_text_new();
gtk_tree_view_column_pack_start(col, renderer, TRUE);
gtk_tree_view_column_set_attributes(col, renderer,
"text", COL_TEXT,
NULL);
gtk_tree_view_append_column(GTK_TREE_VIEW(view), col);
gtk_widget_show_all(view);
return view;
}
</programlisting>
<para>
Note that the tree view will not resize icons for you, but displays
them in their original size. If you want to display
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/gtk-Stock-Items.html">
stock icons</ulink> instead of <literal>GdkPixbuf</literal>s loaded
from file, you should have a look at the <literal>"stock-id"</literal>
property of <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkCellRendererPixbuf.html">
<literal>GtkCellRendererPixbuf</literal></ulink> (and your model column
should be of type <literal>G_TYPE_STRING</literal>, as all stock IDs are
just strings by which to identify the stock icon).
</para>
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-sel-click-menus">
<title>Selections, Double-Clicks and Context Menus</title>
<!-- ************************************************************** -->
<sect1 id="sec-selections">
<title>Handling Selections</title>
<para>
One of the most basic features of a list or tree view is that rows can be selected or unselected.
Selections are handled using the <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html">
<literal>GtkTreeSelection</literal></ulink> object of a tree view. Every
tree view automatically has a <literal>GtkTreeSelection</literal> associated with it, and you can
get it using <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-get-selection">
<literal>gtk_tree_view_get_selection</literal></ulink>. Selections are handled completely on
the tree view side, which means that the model knows nothing about which rows are selected or not.
There is no particular reason why selection handling could not have been implemented with functions
that access the tree view widget directly, but for reasons of API cleanliness and code clarity the
Gtk+ developers decided to create this special <literal>GtkTreeSelection</literal> object that then
internally deals with the tree view widget. You will never need to create a tree selection object,
it will be created for you automatically when you create a new tree view. You only need to use said
<literal>gtk_tree_view_get_selection</literal> function to get a pointer to the selection object.
</para>
<para>
There are three ways to deal with tree view selections: either you get a list of the currently selected
rows whenever you need it, for example within a context menu function, or you keep track of all select
and unselect actions and keep a list of the currently selected rows around for whenever you need them;
as a last resort, you can also traverse your list or tree and check each single row for whether it is
selected or not (which you need to do if you want all rows that are <emphasis>not</emphasis> selected
for example).
</para>
<!-- ************************************************************** -->
<sect2 id="sec-selections-modes">
<title>Selection Modes</title>
<para>
You can use <literal>gtk_tree_selection_set_mode</literal> to influence the way that selections are
handled. There are four selection modes:
</para>
<itemizedlist>
<listitem>
<simpara>
<literal>GTK_SELECTION_NONE</literal> - no items can be selected
</simpara>
</listitem>
<listitem>
<simpara>
<literal>GTK_SELECTION_SINGLE</literal> - no more than one item can be selected
</simpara>
</listitem>
<listitem>
<simpara>
<literal>GTK_SELECTION_BROWSE</literal> - exactly one item is always selected
</simpara>
</listitem>
<listitem>
<simpara>
<literal>GTK_SELECTION_MULTIPLE</literal> - anything between no item and all items can be selected
</simpara>
</listitem>
</itemizedlist>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-selections-current">
<title>Getting the Currently Selected Rows</title>
<para>
You can access the currently selected rows either by traversing all selected rows using
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-selected-foreach">
<literal>gtk_tree_selection_selected_foreach</literal></ulink> or get a
<literal>GList</literal> of tree paths of the selected rows using
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-get-selected-rows">
<literal>gtk_tree_selection_get_selected_rows</literal></ulink>. Note
that this function is only available in Gtk+-2.2 and newer, which means that you can't
use it or need to reimplement it if you want your application to work with older
installations.
</para>
<para>
If the selection mode you are using is either <literal>GTK_SELECTION_SINGLE</literal>
or <literal>GTK_SELECTION_BROWSE</literal>, the most convenient way to get the
selected row is the function <literal>gtk_tree_selection_get_selected</literal>,
which will return <literal>TRUE</literal> and fill in the specified tree iter with
the selected row (if a row is selected), and return <literal>FALSE</literal> otherwise.
It is used like this:
</para>
<programlisting role="C">
...
GtkTreeSelection *selection;
GtkTreeModel *model;
GtkTreeIter iter;
/* This will only work in single or browse selection mode! */
selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(view));
if (gtk_tree_selection_get_selected(selection, &amp;model, &amp;iter))
{
gchar *name;
gtk_tree_model_get (model, &amp;iter, COL_NAME, &amp;name, -1);
g_print ("selected row is: %s\n", name);
g_free(name);
}
else
{
g_print ("no row selected.\n");
}
...
</programlisting>
<para>
One thing you need to be aware of is that you need to take care when removing rows from
the model in a <literal>gtk_tree_selection_selected_foreach</literal> callback, or when
looping through the list that <literal>gtk_tree_selection_get_selected_rows</literal> returns
(because it contains paths, and when you remove rows in the middle, then the old paths will
point to either a non-existing row, or to another row than the one selected). You have two ways
around this problem: one way is to use the solution to removing multiple rows that has been
<link linkend="sec-treemodel-remove-row">described above</link>, ie. to get tree row references
for all selected rows and then remove the rows one by one; the other solution is to sort the
list of selected tree paths so that the last rows come first in the list, so that you remove
rows from the end of the list or tree. You cannot remove rows from within a foreach callback in
any case, that is simply not allowed.
</para>
<para>
Here is an example of how to use <literal>gtk_tree_selection_selected_foreach</literal>:
</para>
<programlisting role="C">
...
gboolean
view_selected_foreach_func (GtkTreeModel *model,
GtkTreePath *path,
GtkTreeIter *iter,
gpointer userdata)
{
gchar *name;
gtk_tree_model_get (model, iter, COL_NAME, &amp;name, -1);
g_print ("%s is selected\n", name);
}
void
do_something_with_all_selected_rows (GtkWidget *treeview)
{
GtkTreeSelection *selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(treeview));
gtk_tree_selection_selected_foreach(selection, view_selected_foreach_func, NULL);
}
void
create_view (void)
{
GtkWidget *view;
GtkTreeSelection *selection;
...
view = gtk_tree_view_new();
...
selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(view));
gtk_tree_selection_set_mode(selection, GTK_SELECTION_MULTIPLE);
...
}
...
</programlisting>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-selections-function">
<title>Using Selection Functions</title>
<para>
You can set up a custom selection function with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-set-select-function">
<literal>gtk_tree_selection_set_select_function</literal></ulink>. This
function will then be called every time a row is going to be selected or
unselected (meaning: it will be called before the selection status of that
row is changed). Selection functions are commonly used for the following things:
</para>
<orderedlist>
<listitem>
<para>
... to keep track of the currently selected items (then you maintain a list
of selected items yourself). In this case, note again that your selection
function is called <emphasis>before</emphasis> the row's selection status is
changed. In other words: if the row is <emphasis>going to be</emphasis>
selected, then the boolean path_currently_selected variable that is passed
to the selection function is still <literal>FALSE</literal>. Also note that
the selection function might not always be called when a row is removed,
so you either have to unselect a row before you remove it to make sure your
selection function is called and removes the row from your list, or check
the validity of a row when you process the selection list you keep. You
should not store tree paths in your self-maintained list of of selected rows,
because whenever rows are added or removed or the model is resorted the paths
might point to other rows. Use tree row references or other unique means of
identifying a row instead.
</para>
</listitem>
<listitem>
<para>
... to tell Gtk+ whether it is allowed to select or unselect that specific row
(you should make sure though that it is otherwise obvious to a user whether a
row can be selected or not, otherwise the user will be confused if she just
cannot select or unselect a row). This is done by returning TRUE or FALSE in the
selection function.
</para>
</listitem>
<listitem>
<para>
... to take additional action whenever a row is selected or unselected.
</para>
</listitem>
</orderedlist>
<para>
Yet another simple example:
</para>
<programlisting role="C">
...
gboolean
view_selection_func (GtkTreeSelection *selection,
GtkTreeModel *model,
GtkTreePath *path,
gboolean path_currently_selected,
gpointer userdata)
{
GtkTreeIter iter;
if (gtk_tree_model_get_iter(model, &amp;iter, path))
{
gchar *name;
gtk_tree_model_get(model, &amp;iter, COL_NAME, &amp;name, -1);
if (!path_currently_selected)
{
g_print ("%s is going to be selected.\n", name);
}
else
{
g_print ("%s is going to be unselected.\n", name);
}
g_free(name);
}
return TRUE; /* allow selection state to change */
}
void
create_view (void)
{
GtkWidget *view;
GtkTreeSelection *selection;
...
view = gtk_tree_view_new();
...
selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(view));
gtk_tree_selection_set_select_function(selection, view_selection_func, NULL, NULL);
...
}
...
</programlisting>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-selections-check-row">
<title>Checking Whether a Row is Selected</title>
<para>
You can check whether a given row is selected or not using the functions
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-iter-is-selected">
<literal>gtk_tree_selection_iter_is_selected</literal></ulink>. or
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-path-is-selected">
<literal>gtk_tree_selection_path_is_selected</literal></ulink>.
If you want to know all rows that are <emphasis>not</emphasis> selected,
for example, you could just traverse the whole list or tree, and use the
above functions to check for each row whether it is selected or not.
</para>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-selections-selecting-rows">
<title>Selecting and Unselecting Rows</title>
<para>
You can select or unselect rows manually with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-select-iter">
<literal>gtk_tree_selection_select_iter</literal></ulink>,
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-select-path">
<literal>gtk_tree_selection_select_path</literal></ulink>,
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-unselect-iter">
<literal>gtk_tree_selection_unselect_iter</literal></ulink>,
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-unselect-path">
<literal>gtk_tree_selection_unselect_path</literal></ulink>,
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-select-all">
<literal>gtk_tree_selection_select_all</literal></ulink>, and
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSelection.html#gtk-tree-selection-unselect-all">
<literal>gtk_tree_selection_unselect_all</literal></ulink>
should you ever need to do that.
</para>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-selections-row-count">
<title>Getting the Number of Selected Rows</title>
<para>
Sometimes you want to know the number of rows that are currently selected (for example to set
context menu entries active or inactive before you pop up a context menu). If you are using
selection mode <literal>GTK_SELECTION_SINGLE</literal> or <literal>GTK_SELECTION_BROWSE</literal>,
this is trivial to check with <literal>gtk_tree_selection_get_selected</literal>, which will return
either <literal>TRUE</literal> or <literal>FALSE</literal> (meaning one selected row or no selected row).
</para>
<para>
If you are using <literal>GTK_SELECTION_MULTIPLE</literal> or want a more general approach that works
for all selection modes, <literal>gtk_tree_selection_count_selected_rows</literal> will return the
information you are looking for. The only caveat with this function is that it only exists in Gtk+-2.2
and newer, so you will have to reimplement it if you want users with old installations that still use Gtk+-2.0
to be able to use your program as well. Here is a way to reimplement this function:
</para>
<programlisting role="C">
static void
count_foreach_helper (GtkTreeModel *model,
GtkTreePath *path,
GtkTreeIter *iter,
gpointer userdata)
{
gint *p_count = (gint*) userdata;
g_assert (p_count != NULL);
*p_count = *p_count + 1;
}
gint
my_tree_selection_count_selected_rows (GtkTreeSelection *selection)
{
gint count = 0;
gtk_tree_selection_selected_foreach(selection, count_foreach_helper, &amp;count);
return count;
}
</programlisting>
</sect2>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-selections-double-click">
<title>Double-Clicks on a Row</title>
<para>
Catching double-clicks on a row is quite easy and is done by connecting
to a tree view's <literal>"row-activated"</literal> signal, like this:
</para>
<programlisting role="C">
void
view_onRowActivated (GtkTreeView *treeview,
GtkTreePath *path,
GtkTreeViewColumn *col,
gpointer userdata)
{
GtkTreeModel *model;
GtkTreeIter iter;
g_print ("A row has been double-clicked!\n");
model = gtk_tree_view_get_model(treeview);
if (gtk_tree_model_get_iter(model, &amp;iter, path))
{
gchar *name;
gtk_tree_model_get(model, &amp;iter, COLUMN_NAME, &amp;name, -1);
g_print ("Double-clicked row contains name %s\n", name);
g_free(name);
}
}
void
create_view (void)
{
GtkWidget *view;
view = gtk_tree_view_new();
...
g_signal_connect(view, "row-activated", (GCallback) view_onRowActivated, NULL);
...
}
</programlisting>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-selections-context-menus">
<title>Context Menus on Right Click</title>
<para>
Context menus are context-dependent menus that pop up when a user right-clicks on a list or tree
and usually let the user do something with the selected items or manipulate the list or tree in other ways.
</para>
<para>
Right-clicks on a tree view are caught just like mouse button clicks are caught with any other widgets, namely
by connecting to the tree view's "button_press_event" signal handler (which is a GtkWidget signal, and as
GtkTreeView is derived from GtkWidget it has this signal as well). Additionally, you should also connect to
the "popup-menu" signal, so users can access your context menu without a mouse. The "popup-menu" signal is
emitted when the user presses Shift-F10. Also, you should make sure that all functions provided in your
context menu can also be accessed by other means such as the application's main menu. See the
<ulink url="http://developer.gnome.org/projects/gup/hig/">GNOME Human Interface Guidelines (HIG)</ulink> for
more details. Straight from the a-snippet-of-code-says-more-than-a-thousand-words-department, some
code to look at:
</para>
<programlisting role="C">
void
view_popup_menu_onDoSomething (GtkWidget *menuitem, gpointer userdata)
{
/* we passed the view as userdata when we connected the signal */
GtkTreeView *treeview = GTK_TREE_VIEW(userdata);
g_print ("Do something!\n");
}
void
view_popup_menu (GtkWidget *treeview, GdkEventButton *event, gpointer userdata)
{
GtkWidget *menu, *menuitem;
menu = gtk_menu_new();
menuitem = gtk_menu_item_new_with_label("Do something");
g_signal_connect(menuitem, "activate",
(GCallback) view_popup_menu_onDoSomething, treeview);
gtk_menu_shell_append(GTK_MENU_SHELL(menu), menuitem);
gtk_widget_show_all(menu);
/* Note: event can be NULL here when called from view_onPopupMenu;
* gdk_event_get_time() accepts a NULL argument */
gtk_menu_popup(GTK_MENU(menu), NULL, NULL, NULL, NULL,
(event != NULL) ? event-&gt;button : 0,
gdk_event_get_time((GdkEvent*)event));
}
gboolean
view_onButtonPressed (GtkWidget *treeview, GdkEventButton *event, gpointer userdata)
{
/* single click with the right mouse button? */
if (event-&gt;type == GDK_BUTTON_PRESS &amp;&amp; event-&gt;button == 3)
{
g_print ("Single right click on the tree view.\n");
/* optional: select row if no row is selected or only
* one other row is selected (will only do something
* if you set a tree selection mode as described later
* in the tutorial) */
if (1)
{
GtkTreeSelection *selection;
selection = gtk_tree_view_get_selection(GTK_TREE_VIEW(treeview));
/* Note: gtk_tree_selection_count_selected_rows() does not
* exist in gtk+-2.0, only in gtk+ &gt;= v2.2 ! */
if (gtk_tree_selection_count_selected_rows(selection) &lt;= 1)
{
GtkTreePath *path;
/* Get tree path for row that was clicked */
if (gtk_tree_view_get_path_at_pos(GTK_TREE_VIEW(treeview),
(gint) event-&gt;x,
(gint) event-&gt;y,
&amp;path, NULL, NULL, NULL))
{
gtk_tree_selection_unselect_all(selection);
gtk_tree_selection_select_path(selection, path);
gtk_tree_path_free(path);
}
}
} /* end of optional bit */
view_popup_menu(treeview, event, userdata);
return TRUE; /* we handled this */
}
return FALSE; /* we did not handle this */
}
gboolean
view_onPopupMenu (GtkWidget *treeview, gpointer userdata)
{
view_popup_menu(treeview, NULL, userdata);
return TRUE; /* we handled this */
}
void
create_view (void)
{
GtkWidget *view;
view = gtk_tree_view_new();
...
g_signal_connect(view, "button-press-event", (GCallback) view_onButtonPressed, NULL);
g_signal_connect(view, "popup-menu", (GCallback) view_onPopupMenu, NULL);
...
}
</programlisting>
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
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<!-- ************************************************************** -->
<chapter id="sec-sorting">
<title>Sorting</title>
<para>
Lists and trees are meant to be sorted. This is done using the
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSortable.html">
<literal>GtkTreeSortable</literal></ulink> interface that can be implemented
by tree models. 'Interface' means that you can just cast a
<literal>GtkTreeModel</literal> into a <literal>GtkTreeSortable</literal> with
<literal>GTK_TREE_SORTABLE(model)</literal> and use the documented tree sortable
functions on it, just like we did before when we cast a list store to a tree model
and used the <literal>gtk_tree_model_foo</literal> family of functions.
Both <literal>GtkListStore</literal> and <literal>GtkTreeStore</literal>
implement the tree sortable interface.
</para>
<para>
The most straight forward way to sort a list store or tree store is to directly use the tree sortable
interface on them. This will sort the store in place, meaning that rows will actually be reordered in
the store if required. This has the advantage that the position of a row in the tree view will always
be the same as the position of a row in the model, in other words: a tree path refering to a row in
the view will always refer to the same row in the model, so you can get a row's iter easily with
<literal>gtk_tree_model_get_iter</literal> using a tree path supplied by the tree view.
This is not only convenient, but also sufficient for most scenarios.
</para>
<para>
However, there are cases when sorting a model in place is not desirable, for
example when several tree views display the same model with different sortings,
or when the unsorted state of the model has some special meaning and needs to
be restored at some point. This is where
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModelSort.html">
<literal>GtkTreeModelSort</literal></ulink> comes in, which is a special model
that maps the unsorted rows of a child model (e.g. a list store or
tree store) into a sorted state without changing the child model.
</para>
<!-- ************************************************************** -->
<sect1 id="sec-sorting-tree-sortable">
<title>GtkTreeSortable</title>
<para>
The tree sortable interface is fairly simple and should be easy to use.
Basically you define a 'sort column ID' integer for every criterion you
might want to sort by and tell the tree sortable which function should be
called to compare two rows (represented by two tree iters) for every sort ID with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSortable.html#gtk-tree-sortable-set-sort-func">
<literal>gtk_tree_sortable_set_sort_func</literal></ulink>. Then you sort the
model by setting the sort column ID and sort order with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSortable.html#gtk-tree-sortable-set-column-id">
<literal>gtk_tree_sortable_set_sort_column_id</literal></ulink>, and the model
will be re-sorted using the compare function you have set up. Your sort column
IDs can correspond to your model columns, but they do not have to (you might
want to sort according to a criterion that is not directly represented by the
data in one single model column, for example). Some code to illustrate this:
</para>
<programlisting role="C">
enum
{
COL_NAME = 0,
COL_YEAR_BORN
};
enum
{
SORTID_NAME = 0,
SORTID_YEAR
};
GtkTreeModel *liststore = NULL;
void
toolbar_onSortByYear (void)
{
GtkTreeSortable *sortable;
GtkSortType order;
gint sortid;
sortable = GTK_TREE_SORTABLE(liststore);
/* If we are already sorting by year, reverse sort order,
* otherwise set it to year in ascending order */
if (gtk_tree_sortable_get_sort_column_id(sortable, &amp;sortid, &amp;order) == TRUE
&amp;&amp; sortid == SORTID_YEAR)
{
GtkSortType neworder;
neworder = (order == GTK_SORT_ASCENDING) ? GTK_SORT_DESCENDING : GTK_SORT_ASCENDING;
gtk_tree_sortable_set_sort_column_id(sortable, SORTID_YEAR, neworder);
}
else
{
gtk_tree_sortable_set_sort_column_id(sortable, SORTID_YEAR, GTK_SORT_ASCENDING);
}
}
/* This is not pretty. Of course you can also use a
* separate compare function for each sort ID value */
gint
sort_iter_compare_func (GtkTreeModel *model,
GtkTreeIter *a,
GtkTreeIter *b,
gpointer userdata)
{
gint sortcol = GPOINTER_TO_INT(userdata);
gint ret = 0;
switch (sortcol)
{
case SORTID_NAME:
{
gchar *name1, *name2;
gtk_tree_model_get(model, a, COL_NAME, &amp;name1, -1);
gtk_tree_model_get(model, b, COL_NAME, &amp;name2, -1);
if (name1 == NULL || name2 == NULL)
{
if (name1 == NULL &amp;&amp; name2 == NULL)
break; /* both equal => ret = 0 */
ret = (name1 == NULL) ? -1 : 1;
}
else
{
ret = g_utf8_collate(name1,name2);
}
g_free(name1);
g_free(name2);
}
break;
case SORTID_YEAR:
{
guint year1, year2;
gtk_tree_model_get(model, a, COL_YEAR_BORN, &amp;year1, -1);
gtk_tree_model_get(model, b, COL_YEAR_BORN, &amp;year2, -1);
if (year1 != year2)
{
ret = (year1 > year2) ? 1 : -1;
}
/* else both equal => ret = 0 */
}
break;
default:
g_return_val_if_reached(0);
}
return ret;
}
void
create_list_and_view (void)
{
GtkTreeSortable *sortable;
...
liststore = gtk_list_store_new(2, G_TYPE_STRING, G_TYPE_UINT);
sortable = GTK_TREE_SORTABLE(liststore);
gtk_tree_sortable_set_sort_func(sortable, SORTID_NAME, sort_iter_compare_func,
GINT_TO_POINTER(SORTID_NAME), NULL);
gtk_tree_sortable_set_sort_func(sortable, SORTID_YEAR, sort_iter_compare_func,
GINT_TO_POINTER(SORTID_YEAR), NULL);
/* set initial sort order */
gtk_tree_sortable_set_sort_column_id(sortable, SORTID_NAME, GTK_SORT_ASCENDING);
...
view = gtk_tree_view_new_with_model(liststore);
...
}
</programlisting>
<para>
Usually things are a bit easier if you make use of the tree view column headers for sorting,
in which case you only need to assign sort column IDs and your compare functions, but do not
need to set the current sort column ID or order yourself (see <link linkend="sec-sorting-view-cols">below</link>).
</para>
<para>
Your tree iter compare function should return a negative value if the row specified by iter a comes before
the row specified by iter b, and a positive value if row b comes before row a. It should return 0 if both
rows are equal according to your sorting criterion (you might want to use a second sort criterion though
to avoid 'jumping' of equal rows when the store gets resorted). Your tree iter compare function should
not take the sort order into account, but assume an ascending sort order (otherwise bad things will happen).
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-sorting-model-sort">
<title>GtkTreeModelSort</title>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModelSort.html">
<literal>GtkTreeModelSort</literal></ulink> is a wrapper tree model.
It takes another tree model such as a list store or a tree store as
child model, and presents the child model to the 'outside' (ie. a tree
view or whoever else is accessing it via the tree model interface) in a
sorted state. It does that without changing the order of the rows in the
child model. This is useful if you want to display the same model in
different tree views with different sorting criteria for each tree view,
for example, or if you need to restore the original unsorted state of
your store again at some point.
</para>
<para>
<literal>GtkTreeModelSort</literal> implements the <literal>GtkTreeSortable</literal> interface, so you can treat
it just as if it was your data store for sorting purposes. Here is the basic setup with a tree view:
</para>
<programlisting role="C">
...
void
create_list_and_view (void)
{
...
liststore = gtk_list_store_new(2, G_TYPE_STRING, G_TYPE_UINT);
sortmodel = gtk_tree_model_sort_new_with_model(liststore);
gtk_tree_sortable_set_sort_func(GTK_TREE_SORTABLE(sortmodel), SORTID_NAME,
sort_func, GINT_TO_POINTER(SORTID_NAME), NULL);
gtk_tree_sortable_set_sort_func(GTK_TREE_SORTABLE(sortmodel), SORTID_YEAR,
sort_func, GINT_TO_POINTER(SORTID_YEAR), NULL);
/* set initial sort order */
gtk_tree_sortable_set_sort_column_id(GTK_TREE_SORTABLE(sortmodel),
SORTID_NAME, GTK_SORT_ASCENDING);
...
view = gtk_tree_view_new_with_model(sortmodel);
...
}
...
</programlisting>
<para>
However, when using the sort tree model, you need to be careful when
you use iters and paths with the model. This is because a path pointing
to a row in the view (and the sort tree model here) does probably not
point to the same row in the child model which is your original list
store or tree store, because the row order in the child model is
probably different from the sorted order. Similarly, an iter that
is valid for the sort tree model is not valid for the child model,
and vice versa. You can convert paths and iters from and to the child
model using
<literal>gtk_tree_model_sort_convert_child_path_to_path</literal>,
<literal>gtk_tree_model_sort_convert_child_iter_to_iter</literal>,
<literal>gtk_tree_model_sort_convert_path_to_child_path</literal>, and
<literal>gtk_tree_model_sort_convert_iter_to_child_iter</literal>.
You are unlikely to need these functions frequently though, as you can
still directly use <literal>gtk_tree_model_get</literal>
on the sort tree model with a path supplied by the tree view.
</para>
<para>
For the tree view, the sort tree model is the 'real' model - it knows
nothing about the sort tree model's child model at all, which means
that any path or iter that you get passed from the tree view in a callback
or otherwise will refer to the sort tree model, and that you need to pass
a path or iter refering to the sort tree model as well if you call tree
view functions.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-sorting-view-cols">
<title>Sorting and Tree View Column Headers</title>
<para>
Unless you have hidden your tree view column headers or use custom tree
view column header widgets, each tree view column's header can be made
clickable. Clicking on a tree view column's header will then sort the list
according to the data in that column. You need to do two things to make this
happen: firstly, you need to tell your model which sort function to use for
which sort column ID with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSortable.html#gtk-tree-sortable-set-sort-func">
<literal>gtk_tree_sortable_set_sort_func</literal></ulink>.
Once you have done this, you tell each tree view column which sort column ID
should be active if this column's header is clicked. This is
done with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeViewColumn.html#gtk-tree-view-column-set-sort-column-id">
<literal>gtk_tree_view_column_set_sort_column_id</literal></ulink>.
</para>
<para>
And that is really all you need to do to get your list or tree sorted.
The tree view columns will automatically set the active sort column ID
and sort order for you if you click on a column header.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-sorting-string-nocase">
<title>Case-insensitive String Comparing</title>
<para>
As described above in the <link linkend="sec-treeview-col-utf8-pango">"GtkCellRendererText, UTF8, and pango markup" section</link>,
all strings that are to be displayed in the tree view need to be encoded
in UTF8 encoding. All ASCII strings are valid UTF8, but as soon as non-ASCII
characters are used, things get a bit tricky and the character encoding matters.
</para>
<para>
Comparing two ASCII strings ignoring the case is trivial and can be done
using <literal>g_ascii_strcasecmp</literal>, for example. <literal>strcasecmp</literal>
will usually do the same, only that it is also locale-aware to some extent.
The only problem is that a lot of users use locale character encodings that
are not UTF8, so <literal>strcasecmp</literal> does not take us very far.
</para>
<para>
<literal>g_utf8_collate</literal> will compare two strings in UTF8 encoding,
but it does not ignore the case. In order to achieve at least half-way correct
linguistic case-insensitive sorting, we need to take a two-step approach.
For example, we could use <literal>g_utf8_casefold</literal> to convert the
strings to compare into a form that is independent of case, and then use
<literal>g_utf8_collate</literal> to compare those two strings (note that the
strings returned by <literal>g_utf8_casefold</literal> will not resemble the
original string in any recognisable way; they will work fine for comparisons
though). Alternatively, one could use <literal>g_utf8_strdown</literal>
on both strings and then compare the results again with
<literal>g_utf8_collate</literal>.
</para>
<para>
Obviously, all this is not going to be very fast, and adds up if you have a
lot of rows. To speed things up, you can create a 'collation key' with
<literal>g_utf8_collate_key</literal> and store that in your model as
well. A collation key is just a string that does not mean anything to
us, but can be used with <literal>strcmp</literal> for string comparison
purposes (which is a lot faster than <literal>g_utf8_collate</literal>).
</para>
<para>
It should be noted that the way <literal>g_utf8_collate</literal> sorts
is dependent on the current locale. Make sure you are not working in the
'C' locale (=default, none specified) before you are wondering about weird
sorting orders. Check with 'echo $LANG' on a command line what you current
locale is set to.
</para>
<para>
Check out the <ulink url="http://developer.gnome.org/doc/API/2.0/glib/glib-Unicode-Manipulation.html#g-utf8-casefold">
"Unicode Manipulation" section</ulink> in the GLib API Reference for more details.
</para>
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-editable-cells">
<title>Editable Cells</title>
<sect1 id="sec-editable-cells-text">
<title>Editable Text Cells</title>
<para>
With <literal>GtkCellRendererText</literal> you can not only display
text, but you can also allow the user to edit a single cell's text
right in the tree view by double-clicking on a cell.
</para>
<para>
To make this work you need to tell the cell renderer that a cell is
editable, which you can do by setting the <literal>"editable"</literal>
property of the text cell renderer in question to <literal>TRUE</literal>.
You can either do this on a per-row basis (which allows you to set each
single cell either editable or not) by connecting the <literal>"editable"</literal>
property to a boolean type column in your tree model using attributes; or you
can just do a ...
</para>
<programlisting role="C">
g_object_set(renderer, "editable", TRUE, NULL);
</programlisting>
<para>
... when you create the renderer, which sets all rows in that particular
renderer column to be editable.
</para>
<para>
Now that our cells are editable, we also want to be notified when a cell has
been edited. This can be achieved by connecting to the cell renderer's
<literal>"edited"</literal> signal:
</para>
<programlisting role="C">
g_signal_connect(renderer, "edited", (GCallback) cell_edited_callback, NULL);
</programlisting>
<para>
This callback is then called whenever a cell has been edited. Instead of
<literal>NULL</literal> we could have passed a pointer to the model as
user data for convenience, as we probably want to store the new value in
the model.
</para>
<para>
The callback for the <literal>"edited"</literal> signal looks like this
(the API reference is a bit lacking in this particular case):
</para>
<programlisting role="C">
void cell_edited_callback (GtkCellRendererText *cell,
gchar *path_string,
gchar *new_text,
gpointer user_data);
</programlisting>
<para>
The tree path is passed to the <literal>"edited"</literal> signal callback
in string form. You can convert this into a <literal>GtkTreePath</literal> with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-new-from-string">
<literal>gtk_tree_path_new_from_string</literal></ulink>, or convert it into an
iter with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-iter-from-string">
<literal>gtk_tree_model_get_iter_from_string</literal></ulink>.
</para>
<para>
Note that the cell renderer will not change the data for you in the store.
After a cell has been edited, you will only receive an <literal>"edited"</literal>
signal. If you do not change the data in the store, the old text will be rendered
again as if nothing had happened.
</para>
<para>
If you have multiple (renderer) columns with editable cells, it is not necessary
to have a different callback for each renderer, you can use the same callback
for all renderers, and attach some data to each renderer, which you can later
retrieve again in the callback to know which renderer/column has been edited.
This is done like this, for example:
</para>
<programlisting role="C">
renderer = gtk_cell_renderer_text_new();
...
g_object_set_data(G_OBJECT(renderer), "my_column_num", GUINT_TO_POINTER(COLUMN_NAME));
...
renderer = gtk_cell_renderer_text_new();
...
g_object_set_data(G_OBJECT(renderer), "my_column_num", GUINT_TO_POINTER(COLUMN_YEAR_OF_BIRTH));
...
</programlisting>
<para>
where COLUMN_NAME and COLUMN_YEAR_OF_BIRTH are enum values. In your callback you can
then get the column number with
</para>
<programlisting role="C">
guint column_number = GPOINTER_TO_UINT(g_object_get_data(G_OBJECT(renderer), "my_column_num"));
</programlisting>
<para>
You can use this mechanism to attach all kinds of custom data to any
object or widget, with a string identifier to your liking.
</para>
<para>
A good example for editable cells is in gtk-demo, which is part of the Gtk+
source code tree (in gtk+-2.x.y/demos/gtk-demo).
</para>
<sect2 id="sec-editable-cells-text-set">
<title>Setting the cursor to a specific cell</title>
<para>
You can move the cursor to a specific cell in a tree view with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-set-cursor">
<literal>gtk_tree_view_set_cursor</literal></ulink>
(or <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-set-cursor-on-cell">
<literal>gtk_tree_view_set_cursor_on_cell</literal></ulink> if you have
multiple editable cell renderers packed into one tree view column), and start editing
the cell if you want to. Similarly, you can get the current row and focus column with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-get-cursor">
<literal>gtk_tree_view_get_cursor</literal></ulink>.
Use <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkWidget.html#gtk-widget-grab-focus">
<literal>gtk_widget_grab_focus(treeview)</literal></ulink> will make sure that the tree view
has the keyboard focus.
</para>
<para>
As the API reference points out, the tree view needs to be realised for cell editing to
happen. In other words: If you want to start editing a specific cell right at program
startup, you need to set up an idle timeout with
<ulink url="http://developer.gnome.org/doc/API/2.0/glib/glib-The-Main-Event-Loop.html#g-idle-add">
<literal>g_idle_add</literal></ulink> that does this for you as soon as the window and
everything else has been realised (return <literal>FALSE</literal> in the
timeout to make it run only once). Alternatively you could connect to the
<literal>"realize"</literal> signal of the treeview with
<literal>g_signal_connect_after</literal> to achieve the same thing.
</para>
<para>
Connect to the tree view's <literal>"cursor-changed"</literal> and/or
<literal>"move-cursor"</literal> signals to keep track of the current
position of the cursor.
</para>
</sect2>
</sect1>
<sect1 id="sec-editable-cells-toggle">
<title>Editable Toggle and Radio Button Cells</title>
<para>
Just like you can set a <literal>GtkCellRendererText</literal> editable,
you can specify whether a <literal>GtkCellRendererToggle</literal> should
change its state when clicked by setting the <literal>"activatable"</literal>
property - either when you create the renderer (in which case all cells in
that column will be clickable) or by connecting the renderer property to a
model column of boolean type via attributes.
</para>
<para>
Connect to the <literal>"toggled"</literal> signal of the toggle cell
renderer to be notified when the user clicks on a toggle button
(or radio button). The user click will not change the value in the
store, or the appearance of the value rendered. The toggle button will
only change state when you update the value in the store. Until then
it will be in an "inconsistent" state, which is also why you should
read the current value of that cell from the model, and not from the
cell renderer.
</para>
<para>
The callback for the <literal>"toggled"</literal> signal looks like this
(the API reference is a bit lacking in this particular case):
</para>
<programlisting role="C">
void cell_toggled_callback (GtkCellRendererToggle *cell,
gchar *path_string,
gpointer user_data);
</programlisting>
<para>
Just like with the <literal>"edited"</literal> signal of the text cell renderer,
the tree path is passed to the <literal>"toggled"</literal> signal callback
in string form. You can convert this into a <literal>GtkTreePath</literal> with
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-path-new-from-string">
<literal>gtk_tree_path_new_from_string</literal></ulink>, or convert it into an
iter with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-iter-from-string">
<literal>gtk_tree_model_get_iter_from_string</literal></ulink>.
</para>
</sect1>
<sect1 id="sec-editable-cells-spin">
<title>Editable Spin Button Cells</title>
<para>
Even though <literal>GtkSpinButton</literal> implements the
<literal>GtkCellEditable</literal> interface (as does
<literal>GtkEntry</literal>), there is no easy way to get
a cell renderer that uses a spin button instead of a normal
entry when in editing mode.
</para>
<para>
To get this functionality, you need to either write a new
cell renderer that works very similar to <literal>GtkCellRendererText</literal>,
or you need to write a new cell renderer class that derives from
the text cell renderer and changes the behaviour in editing mode.
</para>
<para>
The cleanest solution would probably be to write a 'CellRendererNumeric'
that does everything that the text cell renderer does, only that it
has a float type property instead of the <literal>"text"</literal>
property, and an additional digits property. However, no one seems
to have done this yet, so you need to either write one, or find
another solution to get spin buttons in editing mode.
</para>
<para>
Among this tutorial's code examples there is a hackish CellRendererSpin
implementation which is based on <literal>GtkCellRendererText</literal>
and shows spin buttons in editing mode. The implementation is not very
refined though, so you need to make sure it works in your particular
context, and modify it as needed.
</para>
</sect1>
</chapter>
<!-- ************************************************************** -->
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<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-misc">
<title>Miscellaneous</title>
<para>
This section deals with issues and questions that did not seem to
fit in anywhere else. If you can think of something else that should
be dealt with here, do not hesitate to send a mail to
<email>tim at centricular dot net</email>.
</para>
<sect1 id="sec-misc-column-index">
<title>Getting the Column Number from a Tree View Column Widget</title>
<para>
Signal callbacks often only get passed a pointer to a
<literal>GtkTreeViewColumn</literal> when the application programmer
really just wants to know which column <emphasis>number</emphasis>
was affected. There are two ways to find out the position of a column
within the tree view. One way is to write a small helper function that
looks up the column number from a given tree view column object,
like this for example:
<footnote>
<para>This function has been inspired by
<ulink url="http://mail.gnome.org/archives/gtk-list/2003-July/msg00060.html">
this</ulink> mailing list message (thanks to Ken Rastatter for the link and
the topic suggestion).
</para>
</footnote>.
</para>
<programlisting role="C">
/* Returns column number or -1 if not found or on error */
gint
get_col_number_from_tree_view_column (GtkTreeViewColumn *col)
{
GList *cols;
gint num;
g_return_val_if_fail ( col != NULL, -1 );
g_return_val_if_fail ( col-&gt;tree_view != NULL, -1 );
cols = gtk_tree_view_get_columns(GTK_TREE_VIEW(col-&gt;tree_view));
num = g_list_index(cols, (gpointer) col);
g_list_free(cols);
return num;
}
</programlisting>
<para>
Alternatively, it is possible to use <literal>g_object_set_data</literal>
and <literal>g_object_get_data</literal> on the tree view column in order
to identify which column it is. This also has the advantage that you can
still keep track of your columns even if the columns get re-ordered within
the tree view (a feature which is usually disabled though). Use like this:
</para>
<programlisting role="C">
...
enum
{
COL_FIRSTNAME,
COL_SURNAME,
};
...
void
some_callback (GtkWidget *treeview, ..., GtkTreeViewColumn *col, ...)
{
guint colnum = GPOINTER_TO_UINT(g_object_get_data(G_OBJECT(col), "columnnum"));
...
}
void
create_view(void)
{
...
col = gtk_tree_view_column_new();
g_object_set_data(G_OBJECT(col), &quot;columnnum&quot;, GUINT_TO_POINTER(COL_FIRSTNAME));
...
col = gtk_tree_view_column_new();
g_object_set_data(G_OBJECT(col), &quot;columnnum&quot;, GUINT_TO_POINTER(COL_SURNAME));
...
}
</programlisting>
<para>
<literal>"columnnum"</literal> is a random string in the above
example - you can use whatever string you want instead, or store
multiple bits of data (with different string identifiers of course).
Of course you can also combine both approaches, as they do slightly
different things (the first tracks the 'physical' position of a
column within the tree view, the second tracks the 'meaning' of a
column to you, independent of its position within the view).
</para>
</sect1>
<sect1 id="sec-misc-expander-visibility">
<title>Column Expander Visibility</title>
<sect2 id="sec-misc-expander-visibility-hide">
<title>Hiding the Column Expander</title>
<para>
Is it possible to hide the column expander completely? Yes and no.
What follows, is probably a dirty hack at best and there is no
guarantee that it will work with upcoming Gtk+ versions or even with
all past versions (although the latter is easy enough to test of
course).
</para>
<para>
What you can do to hide the column expander is to create an empty
tree view column (containing empty strings, for example) and make
this the first column in the tree view. Then you can hide that
column with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeViewColumn.html#gtk-tree-view-column-set-visible">
<literal>gtk_tree_view_column_set_visible</literal></ulink>. You
will notice that the expander column will now automatically move
to the formerly second, now first, visible column in the tree view.
However, if you call <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-set-expander-column">
<literal>gtk_tree_view_set_expander_column</literal></ulink> right
after the call to <literal>_set_visible</literal>, then the expander
will move back to the hidden column, and no expander is visible
any longer.
</para>
<para>
This means of course that you will have to take care
of expanding and collapsing rows yourself and use the appropriate
tree view functions. While it is at last thinkable that one could
implement custom expanders using custom cell rendereres or pixbuf
cell renderers, this is probably a task that will keep you busy
for more than five minutes. Keep those head ache tablets nearby
if you attempt it anyway...
</para>
</sect2>
<sect2 id="sec-misc-expander-visibility-force">
<title>Forcing Column Expander Visibility</title>
<para>
There are situations where an expander should be visible even if
the row in question does not have any children yet, for instance
when part of a model should only be loaded on request when a node
gets expanded (e.g. to show the contents of a directory). This
is not possible. An expander is only shown if a node has children.
</para>
<para>
A work-around for this problem exists however: simply attach an
empty child row and set the node to collapsed state. Then listen
for the tree view's <literal>"row-expanded"</literal> signal,
and fill the contents of the already existing row with the first
new row, then append new child rows. See
<ulink url="http://mail.gnome.org/archives/gtk-app-devel-list/2003-May/msg00241.html">
this mailing list thread</ulink> for more details.
</para>
</sect2>
</sect1>
<sect1 id="sec-misc-get-renderer-from-click">
<title>Getting the Cell Renderer a Click Event Happened On</title>
<para>
It seems that in many cases when people want to know the cell
renderer a click event happened on, they do not really need to
know the cell renderer, but rather want to modify an individual
cell in a particular column. For this you do not need to know
the cell renderer. Use <literal>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-get-path-at-pos">
gtk_tree_view_get_path_at_pos</ulink></literal> to get a tree
path from the x and y coordinates of the button event that is
passed to you in a <literal>"button-press-event"</literal> signal
callback (if you use the <literal>"row-activated"</literal> signal
to catch double-clicks you get the tree path passed directly into
the callback function). Then convert that tree path into an iter
using <literal><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-iter">
gtk_tree_model_get_iter</ulink></literal> and modify the data in
the cell you want to modify with <literal>gtk_list_store_set</literal>
or <literal>gtk_tree_store_set</literal>.
</para>
<para>
If you really do need to know the cell renderer where a button press
event happened, that is a bit more tricky. Here is a suggestion on
how to approach this issue (the function has not been well-tested and
might not work correctly if the content rendered by one renderer in
different columns varies in width; please send suggestions on how
to fix or improve this function to the author):
</para>
<programlisting role="C">
static gboolean
tree_view_get_cell_from_pos(GtkTreeView *view, guint x, guint y, GtkCellRenderer **cell)
{
GtkTreeViewColumn *col = NULL;
GList *node, *columns, *cells;
guint colx = 0;
g_return_val_if_fail ( view != NULL, FALSE );
g_return_val_if_fail ( cell != NULL, FALSE );
/* (1) find column and column x relative to tree view coordinates */
columns = gtk_tree_view_get_columns(view);
for (node = columns; node != NULL &amp;&amp; col == NULL; node = node-&gt;next)
{
GtkTreeViewColumn *checkcol = (GtkTreeViewColumn*) node-&gt;data;
if (x &gt;= colx &amp;&amp; x &lt; (colx + checkcol-&gt;width))
col = checkcol;
else
colx += checkcol-&gt;width;
}
g_list_free(columns);
if (col == NULL)
return FALSE; /* not found */
/* (2) find the cell renderer within the column */
cells = gtk_tree_view_column_get_cell_renderers(col);
for (node = cells; node != NULL; node = node-&gt;next)
{
GtkCellRenderer *checkcell = (GtkCellRenderer*) node-&gt;data;
guint width = 0, height = 0;
/* Will this work for all packing modes? doesn&apos;t that
* return a random width depending on the last content
* rendered? */
gtk_cell_renderer_get_size(checkcell, GTK_WIDGET(view), NULL, NULL, NULL, &amp;width, NULL);
if (x &gt;= colx &amp;&amp; x &lt; (colx + width))
{
*cell = checkcell;
g_list_free(cells);
return TRUE;
}
colx += width;
}
g_list_free(cells);
return FALSE; /* not found */
}
static gboolean
onButtonPress (GtkWidget *view, GdkEventButton *bevent, gpointer data)
{
GtkCellRenderer *renderer = NULL;
if (tree_view_get_cell_from_pos(GTK_TREE_VIEW(view), bevent-&gt;x, bevent-&gt;y, &amp;renderer))
g_print (&quot;Renderer found\n&quot;);
else
g_print (&quot;Renderer not found!\n&quot;);
}
</programlisting>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-misc-glade">
<title>Glade and Tree Views</title>
<para>
A frequently asked question is how you can add columns to a <literal>GtkTreeView</literal>
in <ulink url="http://glade.gnome.org">Glade</ulink>.
<footnote>
<para>
Do <emphasis>not</emphasis> use Glade to generate code for you. Use Glade to create
the interface. It will save the interface into a .glade file in XML format. You can
then use libglade2 to construct your interface (windows etc.) from that .glade file.
See <ulink url="http://lists.ximian.com/archives/public/glade-devel/2003-February/000015.html">
this mailing list message for a short discussion about why you should avoid Glade
code generation</ulink>.
</para>
</footnote>
The answer is basically that you don't, and that you can't. The only thing glade/libglade
can do for you is to create the <literal>GtkTreeView</literal> for you with nothing in it.
You will need to look up the tree view widget at the start of your application (after the
interface has been created of course), and connect your list store or tree store to it.
Then you will need to add <literal>GtkTreeViewColumn</literal>s and cell renderers to display
the information from the model as you want it to be displayed. You will need to do all
that from within your application.
</para>
<para>
An alternative approach is to derive your own special widget from <literal>GtkTreeView</literal>
that sets up everything as you want it to, and then use the 'custom widget' function in glade.
Of course this still means that you have to write all the code to fill in the columns and
cell renderers and to create the model yourself.
</para>
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
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<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-dnd">
<title>Drag'n'Drop (DnD) **** needs revision ***</title>
<para>
****** NEEDS REVISION
</para>
<para>
This section needs revision more than any other section. If you
know anything about tree view drag'n'drop, you probably know more
than the author of this text. Please give some feedback in that case.
</para>
<para>
If you want to dive into treeview drag'n'drop, you might want to
check out <ulink url="http://mail.gnome.org/archives/gtk-devel-list/2001-November/msg00018.html">
Owen Taylor's mail on that topic</ulink>. It might not be completely
identical to what has actually been implemented, but it gives a great
overview, and provides more information than the docs do.
</para>
<para>
In addition to the standard Gtk+ Drag and Drop mechanisms that work
with any widget, there are special Drag and Drop mechanisms just for
the tree view widget. You usually want to use the tree-view specific
Drag-and-Drop framework.
</para>
<!-- ************************************************************** -->
<sect1 id="sec-dnd-selected-item-info">
<title>Drag'n'Dropping Row-Unrelated Data to and from a Tree View from other Windows or Widgets</title>
<para>
Drag'n'Dropping general information from or to a tree view widget works
just like it works with any other widget and involves the standard
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/gtk-Drag-and-Drop.html">
Gtk+ Drag and Drop</ulink> mechanisms. If you use this, you can
receive drops to or initiate drags from anywhere in your tree view
(including empty sections). This is not row- or column-specific and
<emphasis>is most likely not want you want</emphasis>.
Nevertheless, here is a small example
of a tree view in which you can drag'n'drop URIs from other
applications (browsers, for example), with the dropped URIs just
being appended to the list (note that usually you would probably
rather want to set up your whole window as a target then and not
just the tree view widget):
</para>
<programlisting role="C">
#include &lt;gtk/gtk.h&gt;
enum
{
COL_URI = 0,
NUM_COLS
} ;
void
view_onDragDataReceived(GtkWidget *wgt, GdkDragContext *context, int x, int y,
GtkSelectionData *seldata, guint info, guint time,
gpointer userdata)
{
GtkTreeModel *model;
GtkTreeIter iter;
model = GTK_TREE_MODEL(userdata);
gtk_list_store_append(GTK_LIST_STORE(model), &amp;iter);
gtk_list_store_set(GTK_LIST_STORE(model), &amp;iter, COL_URI, (gchar*)seldata-&gt;data, -1);
}
static GtkWidget *
create_view_and_model (void)
{
GtkTreeViewColumn *col;
GtkCellRenderer *renderer;
GtkListStore *liststore;
GtkWidget *view;
liststore = gtk_list_store_new(NUM_COLS, G_TYPE_STRING);
view = gtk_tree_view_new_with_model(GTK_TREE_MODEL(liststore));
g_object_unref(liststore); /* destroy model with view */
col = gtk_tree_view_column_new();
renderer = gtk_cell_renderer_text_new();
gtk_tree_view_column_set_title(col, &quot;URI&quot;);
gtk_tree_view_append_column(GTK_TREE_VIEW(view), col);
gtk_tree_view_column_pack_start(col, renderer, TRUE);
gtk_tree_view_column_add_attribute(col, renderer, &quot;text&quot;, COL_URI);
gtk_tree_selection_set_mode(gtk_tree_view_get_selection(GTK_TREE_VIEW(view)),
GTK_SELECTION_SINGLE);
/* Make tree view a destination for Drag&apos;n&apos;Drop */
if (1)
{
enum
{
TARGET_STRING,
TARGET_URL
};
static GtkTargetEntry targetentries[] =
{
{ &quot;STRING&quot;, 0, TARGET_STRING },
{ &quot;text/plain&quot;, 0, TARGET_STRING },
{ &quot;text/uri-list&quot;, 0, TARGET_URL },
};
gtk_drag_dest_set(view, GTK_DEST_DEFAULT_ALL, targetentries, 3,
GDK_ACTION_COPY|GDK_ACTION_MOVE|GDK_ACTION_LINK);
g_signal_connect(view, &quot;drag_data_received&quot;,
G_CALLBACK(view_onDragDataReceived), liststore);
}
return view;
}
int
main (int argc, char **argv)
{
GtkWidget *window, *vbox, *view, *label;
gtk_init(&amp;argc, &amp;argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
g_signal_connect(window, &quot;delete_event&quot;, gtk_main_quit, NULL); /* dirty */
gtk_window_set_default_size(GTK_WINDOW(window), 400, 200);
vbox = gtk_vbox_new(FALSE, 0);
gtk_container_add(GTK_CONTAINER(window), vbox);
label = gtk_label_new(&quot;\nDrag and drop links from your browser into the tree view.\n&quot;);
gtk_box_pack_start(GTK_BOX(vbox), label, FALSE, FALSE, 0);
view = create_view_and_model();
gtk_box_pack_start(GTK_BOX(vbox), view, TRUE, TRUE, 0);
gtk_widget_show_all(window);
gtk_main();
return 0;
}
</programlisting>
<para>
If you are receiving drops into a tree view, you can connect to the view's
<literal>"drag-motion"</literal> signal to track the mouse pointer while
it is in a drag and drop operation over the tree view. This is useful for
example if you want to expand a collapsed node in a tree when the mouse
hovers above the node for a certain amount of time during a drag'n'drop
operation. Here is an example of how to achieve this:
</para>
<programlisting role="C">
/***************************************************************************
*
* onDragMotion_expand_timeout
*
* Timeout used to make sure that we expand rows only
* after hovering about them for a certain amount
* of time while doing Drag&apos;n&apos;Drop
*
***************************************************************************/
gboolean
onDragMotion_expand_timeout (GtkTreePath **path)
{
g_return_val_if_fail ( path != NULL, FALSE );
g_return_val_if_fail ( *path != NULL, FALSE );
gtk_tree_view_expand_row(GTK_TREE_VIEW(view), *path, FALSE);
return FALSE; /* only call once */
}
/***************************************************************************
*
* view_onDragMotion: we don&apos;t want to expand unexpanded nodes
* immediately when the mouse pointer passes across
* them during DnD. Instead, we only want to expand
* the node if the pointer has been hovering above the
* node for at least 1.5 seconds or so. To achieve this,
* we use a timeout that is removed whenever the row
* in focus changes.
*
***************************************************************************/
static gboolean
view_onDragMotion (GtkWidget *widget, GdkDragContext *context, gint x,
gint y, guint time, gpointer data)
{
static GtkTreePath *lastpath; /* NULL */
GtkTreePath *path = NULL;
if (gtk_tree_view_get_path_at_pos(GTK_TREE_VIEW(widget), x, y, &amp;path, NULL, NULL, NULL))
{
if (!lastpath || ((lastpath) &amp;&amp; gtk_tree_path_compare(lastpath, path) != 0))
{
(void) g_source_remove_by_user_data(&amp;lastpath);
if (!gtk_tree_view_row_expanded(GTK_TREE_VIEW(widget), path))
{
/* 1500 = 1.5 secs */
g_timeout_add(1500, (GSourceFunc) onDragMotion_expand_timeout, &amp;lastpath);
}
}
}
else
{
g_source_remove_by_user_data(&amp;lastpath);
}
if (lastpath)
gtk_tree_path_free(lastpath);
lastpath = path;
return TRUE;
}
</programlisting>
<para>
Connect to the view's <literal>"drag-drop"</literal> signal to be called
when the drop happens. You can translate the coordinates provided into
a tree path with <ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeView.html#gtk-tree-view-get-path-at-pos">
<literal>gtk_tree_view_get_path_at_pos</literal></ulink>.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-dnd-rows-within-tree">
<title>Dragging Rows Around Within a Tree **** TODO ***</title>
<para>
****** TODO
</para>
<para>
Both <literal>GtkListStore</literal> and <literal>GtkTreeStore</literal>
implement the <literal>GtkTreeDragDest</literal> and <literal>GtkTreeDragSource</literal>
interfaces, which means that they have in-built support for row reordering. You need to
call <literal>gtk_tree_view_set_reorderable</literal> to activate this, and then connect
to the tree model's signals to catch the reorderings that take place.
</para>
<para>
*** SOMEONE NEEDS TO WRITE THIS SECTION (I have never gotten this to work
in a way that does not suck, ie. where one does not have to place the row
to move exact to the pixel on the target row).
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-dnd-rows-between-trees">
<title>Dragging Rows from One Tree to Another **** TODO ***</title>
<para>
****** TODO (is this possible at all in Gtk+ &lt;= 2.2?)
</para>
</sect1>
</chapter>
<!-- ************************************************************** -->
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<!-- ************************************************************** -->
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<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-custom-models">
<title>Writing Custom Models</title>
<!-- ************************************************************** -->
<sect1 id="sec-custom-models-when">
<title>When is a Custom Model Useful?</title>
<para>
A custom tree model gives you complete control over your data and how it is
represented to the outside (e.g. to the tree view widget). It has the advantage
that you can store, access and modify your data exactly how you need it, and
you can optimise the way your data is stored and retrieved, as you can write
your own functions to access your data and need not rely solely on the
<literal>gtk_tree_model_get</literal>. A model tailored to your needs will probably
also be a lot faster than the generic list and tree stores that come with gtk
and that have been designed with flexibility in mind.
</para>
<para>
Another case where a custom model might come in handy is when you have all your
data already stored in an external tree-like structure (for example a libxml2 XML
tree) and only want to display that structure. Then you could write a custom model
that maps that structure to a tree model (which is probably not quite as trivial
as it sounds though).
</para>
<para>
Using a custom model you could also implement a filter model that only displays
certain rows according to some filter criterion instead of displaying all rows
(Gtk+-2.4 has a filter model, <literal>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModelFilter.html">
GtkTreeModelFilter</ulink></literal>, that
does exactly that and much more, but you might want to implement this yourself
anyway. If you need to use GtkTreeModelFilter in Gtk-2.0 or Gtk-2.2,
check out the code examples of this tutorial - there is GuiTreeModelFilter,
which is basically just the original GtkTreeModelFilter but has been made
to work with earlier Gtk-2.x versions and has a different name space, so that
it does not clash with Gtk-2.4).
</para>
<para>
However, all this comes at a cost: you are unlikely to write a useful custom model
in less than a thousand lines, unless you strip all newline characters. Writing a
custom model is not as difficult as it might sound though, and it may well be worth the
effort, not least because it will result in much saner code if you have a lot of
data to keep track of.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-custom-models-what">
<title>What Does Writing a Custom Model Involve?</title>
<para>
Basically, all you need to do is to write a new GObject that implements the
<literal>GtkTreeModel</literal> interface, <literal>GtkTreeModelIface</literal>.
Intimate knowledge about the GLib GObject system is not a requirement - you
just need to copy some boilerplate code and modify it a bit. The core of your
custom tree model is your own implementation of a couple of
<literal>gtk_tree_model_foo</literal> functions that reveal the structure of your
data, ie. how many rows there are, how many
children a row has, how many columns there are and what type of data they contain.
Furthermore, you need to provide functions that convert a tree path to a tree iter
and a tree iter to a tree path. Additionally, you should provide some functions to
add and remove rows to your custom model, but those are only ever used by yourself
anyway, so they do not fall within the scope of the tree model interface.
</para>
<para>
The functions you <emphasis>need</emphasis> to implement are:
</para>
<itemizedlist>
<listitem>
<para>
<literal>get_flags</literal> - tells the outside that your model has certain special characterstics, like persistent iters.
</para>
</listitem>
<listitem>
<para>
<literal>get_n_columns</literal> - how many data fields per row are visible to the outside that uses gtk_tree_model_get, e.g. cell renderer attributes
</para>
</listitem>
<listitem>
<para>
<literal>get_column_type</literal> - what type of data is stored in a data field (model column) that is visible to the outside
</para>
</listitem>
<listitem>
<para>
<literal>get_iter</literal> - take a tree path and fill an iter structure so that you know which row it refers to
</para>
</listitem>
<listitem>
<para>
<literal>get_path</literal> - take an iter and convert it into a tree path, ie. the 'physical' position within the model
</para>
</listitem>
<listitem>
<para>
<literal>get_value</literal> - retrieve data from a row
</para>
</listitem>
<listitem>
<para>
<literal>iter_next</literal> - take an iter structure and make it point to the next row
</para>
</listitem>
<listitem>
<para>
<literal>iter_children</literal> - tell whether the row represented by a given iter has any children or not
</para>
</listitem>
<listitem>
<para>
<literal>iter_n_children</literal> - tell how many children a row represented by a given iter has
</para>
</listitem>
<listitem>
<para>
<literal>iter_nth_child</literal> - set a given iter structure to the n-th child of a given parent iter
</para>
</listitem>
<listitem>
<para>
<literal>iter_parent</literal> - set a given iter structure to the parent of a given child iter
</para>
</listitem>
</itemizedlist>
<para>
It is up to you to decide which of your data you make 'visible' to the outside in form of model columns
and which not. You can always implement functions specific to your custom model that will return any data
in any form you desire. You only <emphasis>need</emphasis> to make data 'visble' to the outside via the GType and GValue system
if you want the tree view components to access it (e.g. when setting cell renderer attributes).
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-custom-model-list">
<title>Example: A Simple Custom List Model</title>
<para>
What follows is the outline for a simple custom list model. You can find the complete source
code for this model <link linkend="sec-custom-model-code">below</link>. The beginning
of the code might look a bit scary, but you can just skip most of the GObject and GType
stuff and proceed to the heart of the custom list, ie. the implementation of the
tree model functions.
</para>
<para>
Our list model is represented by a simple list of records, where each row corresponds to a
<literal>CustomRecord</literal> structure which keeps track of the data we are interested in.
For now, we only want to keep track of persons' names and years of birth (usually this would not really
justify a custom model, but this is still just an example). It is trivial to extend
the model to deal with additional fields in the <literal>CustomRecord</literal> structure.
</para>
<para>
Within the model, more precisely: the <literal>CustomList</literal> structure, the list is
stored as a pointer array, which not only provides fast access to the n-th record in the list,
but also comes in handy later on when we add sorting. Apart from that, any other kind of
list-specific data would go in this structure as well (the active sort column, for example, or
hash tables to speed up searching for a specific row, etc.).
</para>
<para>
Each row in our list is represented by a <literal>CustomRecord</literal> structure. You can
store whatever other data you need in that structure. How you make row data available is up
to you. Either you export it via the tree model interface using the
<ulink url="http://developer.gnome.org/doc/API/2.0/gobject/gobject-Standard-Parameter-and-Value-Types.html">GValue system</ulink>,
so that you can use <literal>gtk_tree_model_get</literal> to retrieve your data, or you
provide custom model-specific functions to retrieve data, for example <literal>custom_list_get_name</literal>,
taking a tree iter or a tree path as argument. Of course you can also do both.
</para>
<para>
Furthermore, you will need to provide your own functions to add rows, remove rows, and
set or modify row data, and you need to let the view and others know whenever something
changes in your model by emitting the appropriate signals via the provided tree model
functions.
</para>
<para>
Some thought should go into how exactly you fill the
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#GtkTreeIter">
<literal>GtkTreeIter</literal> fields</ulink> of the tree iters used by
your model. You have three pointer fields at your disposal. These should be filled
so that you can easily identify the row given the iter, and should also facilitate
access to the next row and the parent row (if any). If your model advertises to
have persistent iters, you need to make sure that the content of your iters is
perfectly valid even if the user stores it somewhere for later use and the model
gets changed or reordered. The 'stamp' field of a tree iter should be filled by
a random model-instance-specific integer that was assigned to the model when it
was created. This way you can catch iters that do not belong to your model.
If your model does not have persistent iters, then you should change the model's
stamp whenever the model changes, so that you can catch invalid iters that get
passed to your functions (note: in the code below we do not check the stamp
of the iters in order to save a couple of lines of code to print here).
</para>
<para>
In our specific example, we simply store a pointer to a row's
<literal>CustomRecord</literal> structure in our model's tree iters,
which is valid as long as the row exists. Additionally we store the
position of a row within the list in the <literal>CustomRecord</literal>
as well, which is not only intuitive, but is also useful later on
when we resort the list.
</para>
<para>
If you want to store an integer value in an iter's fields, you should
use GLib's <literal>GINT_TO_POINTER</literal> and
<literal>GPOINTER_TO_INT</literal> macros for that.
</para>
<para>
Let's look at the code sections in a bit more detail:
</para>
<!-- ************************************************************** -->
<sect2 id="sec-custom-model-list-header">
<title>custom-list.h</title>
<para>
The <link linkend="sec-custom-model-code-header">header file</link> for our
custom list model defines some standard type casts and type check macros,
our <literal>CustomRecord</literal> structure, our <literal>CustomList</literal>
structure, and some enums for the model columns we are exporting.
</para>
<para>The <literal>CustomRecord</literal> structure represents one row, while
the <literal>CustomList</literal> structure contains all list-specific data.
You can add additional fields to both structures without problems. For example,
you might need a function that quickly looks up rows given the name or year
of birth, for which additional hashtables or so might come in handy
(which you would need to keep up to date as you insert, modify or remove
rows of course).
</para>
<para>
The only function you must export is <literal>custom_list_get_type</literal>,
as it is used by the type check and type cast macros that are also defined
in the header file. Additionally, we want to export a function to create one
instance of our custom model, and a function that adds some rows. You will
probably add more custom model-specific functions to modify the model as you
extend it to suit your needs.
</para>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-custom-model-list-body">
<title>custom-list.c</title>
<para>
Firstly, we need some boilerplate code to register our custom model
with the GObject type system. You can skip this section and proceed to the
tree model implementation.
</para>
<para>
Functions of interested in this section are <literal>custom_list_init</literal> and
<literal>custom_list_get_type</literal>. In <literal>custom_list_init</literal> we
define what data type our exported model columns have, and how many columns we export.
Towards the end of <literal>custom_list_get_type</literal> we register the
<literal>GtkTreeModel</literal> interface with our custom model object. This is where
we can also register additional interfaces (e.g. <literal>GtkTreeSortable</literal>
or one of the Drag'n'Drop interfaces) that we want to implement.
</para>
<para>
In <literal>custom_list_tree_model_init</literal> we override those tree model functions
that we need to implement with our own functions. If it is beneficial for your model to
know which rows are currently displayed in the tree view (for example for caching), you
might want to override the <literal>ref_node</literal> and <literal>unref_node</literal>
functions as well.
</para>
<para>
Let's have a look at the heart of the object type registration:
</para>
<programlisting role="C">
GType
custom_list_get_type (void)
{
static GType custom_list_type = 0;
if (custom_list_type)
return custom_list_type;
/* Some boilerplate type registration stuff */
if (1)
{
static const GTypeInfo custom_list_info =
{
sizeof (CustomListClass),
NULL, /* base_init */
NULL, /* base_finalize */
(GClassInitFunc) custom_list_class_init,
NULL, /* class finalize */
NULL, /* class_data */
sizeof (CustomList),
0, /* n_preallocs */
(GInstanceInitFunc) custom_list_init
};
custom_list_type = g_type_register_static (G_TYPE_OBJECT, "CustomList",
&amp;custom_list_info, (GTypeFlags)0);
}
/* Here we register our GtkTreeModel interface with the type system */
if (1)
{
static const GInterfaceInfo tree_model_info =
{
(GInterfaceInitFunc) custom_list_tree_model_init,
NULL,
NULL
};
g_type_add_interface_static (custom_list_type, GTK_TYPE_TREE_MODEL, &amp;tree_model_info);
}
return custom_list_type;
}
</programlisting>
<para>
Here we just return the type assigned to our custom list by the type system
if we have already registered it. If not, we register it and save the type.
Of the three callbacks that we pass to the type system, only two are of
immediate interest to us, namely <literal>custom_list_tree_model_init</literal>
and <literal>custom_list_init</literal>.
</para>
<para>
In <literal>custom_list_tree_model_init</literal> we fill the tree model
interface structure with pointers to our own functions (at least the ones
we implement):
</para>
<programlisting role="C">
static void
custom_list_tree_model_init (GtkTreeModelIface *iface)
{
/* Here we override the GtkTreeModel
* interface functions that we implement */
iface-&gt;get_flags = custom_list_get_flags;
iface-&gt;get_n_columns = custom_list_get_n_columns;
iface-&gt;get_column_type = custom_list_get_column_type;
iface-&gt;get_iter = custom_list_get_iter;
iface-&gt;get_path = custom_list_get_path;
iface-&gt;get_value = custom_list_get_value;
iface-&gt;iter_next = custom_list_iter_next;
iface-&gt;iter_children = custom_list_iter_children;
iface-&gt;iter_has_child = custom_list_iter_has_child;
iface-&gt;iter_n_children = custom_list_iter_n_children;
iface-&gt;iter_nth_child = custom_list_iter_nth_child;
iface-&gt;iter_parent = custom_list_iter_parent;
}
</programlisting>
<para>
In <literal>custom_list_init</literal> we initialised the custom
list structure to sensible default values. This function will be
called whenever a new instance of our custom list is created, which
we do in <literal>custom_list_new</literal>.
</para>
<para>
<literal>custom_list_finalize</literal> is called just before one
of our lists is going to be destroyed. You should free all resources
that you have dynamically allocated in there.
</para>
<para>
Having taken care of all the type system stuff, we now come to the heart of our custom model,
namely the tree model implementation. Our tree model functions need to behave exactly as the
API reference requires them to behave, including all special cases, otherwise things will not
work. Here is a list of links to the API reference descriptions of the functions we are
implementing:
</para>
<itemizedlist>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-flags">gtk_tree_model_get_flags</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-n-columns">gtk_tree_model_get_n_columns</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-column-type">gtk_tree_model_get_column_type</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-iter">gtk_tree_model_get_iter</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-path">gtk_tree_model_get_path</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-get-value">gtk_tree_model_get_value</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-next">gtk_tree_model_iter_next</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-children">gtk_tree_model_iter_children</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-has-child">gtk_tree_model_iter_has_child</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-n-children">gtk_tree_model_iter_n_children</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-nth-child">gtk_tree_model_iter_nth_child</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-iter-parent">gtk_tree_model_iter_parent</ulink></para>
</listitem>
</itemizedlist>
<para>
Almost all functions are more or less straight-forward and self-explanatory
in connection with the API reference descriptions, so you should be able to
jump right into <link linkend="sec-custom-model-code-body">the code</link>
and see how it works.
</para>
<para>
After the tree model implementation we have those functions that are specific to our
custom model. <literal>custom_list_new</literal> will create a new custom list for us,
and <literal>custom_list_append_record</literal> will append a new record to the end
of the list. Note the call to <literal>gtk_tree_model_row_inserted</literal> at the
end of our append function, which emits a <literal>"row-inserted"</literal>
signal on the model and informs all interested objects (tree views, tree row references)
that a new row has been inserted, and where it has been inserted.
</para>
<para>
You will need to emit tree model signals whenever something changes, e.g. rows are inserted,
removed, or reordered, or when a row changes from a child-less row to a row which has children,
or if a row's data changes. Here are the functions you need to use in those cases (we only
implement row insertions here - other cases are left as an exercise for the reader):
</para>
<itemizedlist>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-row-inserted">gtk_tree_model_row_inserted</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-row-changed">gtk_tree_model_row_changed</ulink> (makes tree view redraw that row)</para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-row-has-child-toggled">gtk_tree_model_row_has_child_toggled</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-row-deleted">gtk_tree_model_row_deleted</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeModel.html#gtk-tree-model-rows-reordered">gtk_tree_model_rows_reordered</ulink>
(note <ulink url="http://bugs.gnome.org/show_bug.cgi?id=124790">bug 124790</ulink>)</para>
</listitem>
</itemizedlist>
<para>
And that is all you have to do to write a custom model.
</para>
</sect2>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-custom-model-tree">
<title>From a List to a Tree</title>
<para>
Writing a custom model for a tree is a bit trickier than a simple list model,
but follows the same pattern. Basically you just need to extend the above
model to cater for the case of children. You could do this by keeping track
of the whole tree hierarchy in the <literal>CustomList</literal> structure,
using GLib N-ary trees for example, or you could do this by keeping track
of each row's children within the row's <literal>CustomRecord</literal>
structure, keeping only a pointer to the (invisible) root record in the
<literal>CustomList</literal> structure.
</para>
<para>
TODO: do we need anything else here?
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-custom-model-sorting">
<title>Additional interfaces, here: the GtkTreeSortable interface</title>
<para>
A custom model can implement additional interfaces to extend its functionality.
Additional interfaces are:
</para>
<itemizedlist>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/GtkTreeSortable.html#GtkTreeSortableIface">GtkTreeSortableIface</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/gtk-GtkTreeView-drag-and-drop.html#GtkTreeDragDestIface">GtkTreeDragDestIface</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://developer.gnome.org/doc/API/2.0/gtk/gtk-GtkTreeView-drag-and-drop.html#GtkTreeDragSourceIface">GtkTreeDragSourceIface</ulink></para>
</listitem>
</itemizedlist>
<para>
Here, we will show how to implement additional interfaces at the example of the
<literal>GtkTreeSortable</literal> interface, which we will implement only partially
(enough to make it functional and useful though).
</para>
<para>
Three things are necessary to add another interface: we will need to register the interface
with our model in <literal>custom_list_get_type</literal>, provide an interface init function
where we set the interface to our own implementation of the interface functions,
and then provide the implementation of those functions.
</para>
<para>
Firstly, we need to provide the function prototypes for our functions at the beginning of
the file:
</para>
<programlisting role="C">
/* custom-list.c */
...
/* -- GtkTreeSortable interface functions -- */
static gboolean custom_list_sortable_get_sort_column_id (GtkTreeSortable *sortable,
gint *sort_col_id,
GtkSortType *order);
static void custom_list_sortable_set_sort_column_id (GtkTreeSortable *sortable,
gint sort_col_id,
GtkSortType order);
static void custom_list_sortable_set_sort_func (GtkTreeSortable *sortable,
gint sort_col_id,
GtkTreeIterCompareFunc sort_func,
gpointer user_data,
GtkDestroyNotify destroy_func);
static void custom_list_sortable_set_default_sort_func (GtkTreeSortable *sortable,
GtkTreeIterCompareFunc sort_func,
gpointer user_data,
GtkDestroyNotify destroy_func);
static gboolean custom_list_sortable_has_default_sort_func (GtkTreeSortable *sortable);
static void custom_list_resort (CustomList *custom_list);
...
</programlisting>
<para>
Next, let's extend our <literal>CustomList</literal> structure with a field for the currently active
sort column ID and one for the sort order, and add an enum for the sort column IDs:
</para>
<programlisting role="C">
/* custom-list.h */
enum
{
SORT_ID_NONE = 0,
SORT_ID_NAME,
SORT_ID_YEAR_BORN,
};
...
struct _CustomList
{
GObject parent;
guint num_rows; /* number of rows that we have */
CustomRecord **rows; /* a dynamically allocated array of pointers to the
* CustomRecord structure for each row */
gint n_columns;
GType column_types[CUSTOM_LIST_N_COLUMNS];
gint sort_id;
GtkSortType sort_order;
gint stamp; /* Random integer to check whether an iter belongs to our model */
};
...
</programlisting>
<para>
Now, we make sure we initialise the new fields in <literal>custom_list_new</literal>, and add our new
interface:
</para>
<programlisting role="C">
...
static void custom_list_sortable_init (GtkTreeSortableIface *iface);
...
void
custom_list_init (CustomList *custom_list)
{
...
custom_list-&gt;sort_id = SORT_ID_NONE;
custom_list-&gt;sort_order = GTK_SORT_ASCENDING;
...
}
GType
custom_list_get_type (void)
{
...
/* Add GtkTreeSortable interface */
if (1)
{
static const GInterfaceInfo tree_sortable_info =
{
(GInterfaceInitFunc) custom_list_sortable_init,
NULL,
NULL
};
g_type_add_interface_static (custom_list_type, GTK_TYPE_TREE_SORTABLE, &amp;tree_sortable_info);
}
...
}
static void
custom_list_sortable_init (GtkTreeSortableIface *iface)
{
iface-&gt;get_sort_column_id = custom_list_sortable_get_sort_column_id;
iface-&gt;set_sort_column_id = custom_list_sortable_set_sort_column_id;
iface-&gt;set_sort_func = custom_list_sortable_set_sort_func; /* NOT SUPPORTED */
iface-&gt;set_default_sort_func = custom_list_sortable_set_default_sort_func; /* NOT SUPPORTED */
iface-&gt;has_default_sort_func = custom_list_sortable_has_default_sort_func; /* NOT SUPPORTED */
}
</programlisting>
<para>
Now that we have finally taken care of the administrativa, we implement the tree sortable interface functions:
</para>
<programlisting role="C">
static gboolean
custom_list_sortable_get_sort_column_id (GtkTreeSortable *sortable,
gint *sort_col_id,
GtkSortType *order)
{
CustomList *custom_list;
g_return_val_if_fail ( sortable != NULL , FALSE );
g_return_val_if_fail ( CUSTOM_IS_LIST(sortable), FALSE );
custom_list = CUSTOM_LIST(sortable);
if (sort_col_id)
*sort_col_id = custom_list-&gt;sort_id;
if (order)
*order = custom_list-&gt;sort_order;
return TRUE;
}
static void
custom_list_sortable_set_sort_column_id (GtkTreeSortable *sortable,
gint sort_col_id,
GtkSortType order)
{
CustomList *custom_list;
g_return_if_fail ( sortable != NULL );
g_return_if_fail ( CUSTOM_IS_LIST(sortable) );
custom_list = CUSTOM_LIST(sortable);
if (custom_list-&gt;sort_id == sort_col_id &amp;&amp; custom_list-&gt;sort_order == order)
return;
custom_list-&gt;sort_id = sort_col_id;
custom_list-&gt;sort_order = order;
custom_list_resort(custom_list);
/* emit "sort-column-changed" signal to tell any tree views
* that the sort column has changed (so the little arrow
* in the column header of the sort column is drawn
* in the right column) */
gtk_tree_sortable_sort_column_changed(sortable);
}
static void
custom_list_sortable_set_sort_func (GtkTreeSortable *sortable,
gint sort_col_id,
GtkTreeIterCompareFunc sort_func,
gpointer user_data,
GtkDestroyNotify destroy_func)
{
g_warning ("%s is not supported by the CustomList model.\n", __FUNCTION__);
}
static void
custom_list_sortable_set_default_sort_func (GtkTreeSortable *sortable,
GtkTreeIterCompareFunc sort_func,
gpointer user_data,
GtkDestroyNotify destroy_func)
{
g_warning ("%s is not supported by the CustomList model.\n", __FUNCTION__);
}
static gboolean
custom_list_sortable_has_default_sort_func (GtkTreeSortable *sortable)
{
return FALSE;
}
</programlisting>
<para>
Now, last but not least, the only thing missing is the function that does the actual
sorting. We do not implement <literal>set_sort_func</literal>, <literal>set_default_sort_func</literal>
and <literal>set_has_default_sort_func</literal> because we use our own internal sort function here.
</para>
<para>
The actual sorting is done using GLib's <literal>g_qsort_with_data</literal> function, which sorts an
array using the QuickSort algorithm. Note how we notify the tree view and other objects of the new
row order by emitting the "rows-reordered" signal on the tree model.
</para>
<programlisting role="C">
static gint
custom_list_compare_records (gint sort_id, CustomRecord *a, CustomRecord *b)
{
switch(sort_id)
{
case SORT_ID_NONE:
return 0;
case SORT_ID_NAME:
{
if ((a-&gt;name) &amp;&amp; (b-&gt;name))
return g_utf8_collate(a-&gt;name, b-&gt;name);
if (a-&gt;name == b-&gt;name)
return 0; /* both are NULL */
else
return (a-&gt;name == NULL) ? -1 : 1;
}
case SORT_ID_YEAR_BORN:
{
if (a-&gt;year_born == b-&gt;year_born)
return 0;
return (a-&gt;year_born &gt; b-&gt;year_born) ? 1 : -1;
}
}
g_return_val_if_reached(0);
}
static gint
custom_list_qsort_compare_func (CustomRecord **a, CustomRecord **b, CustomList *custom_list)
{
gint ret;
g_assert ((a) &amp;&amp; (b) &amp;&amp; (custom_list));
ret = custom_list_compare_records(custom_list-&gt;sort_id, *a, *b);
/* Swap -1 and 1 if sort order is reverse */
if (ret != 0 &amp;&amp; custom_list-&gt;sort_order == GTK_SORT_DESCENDING)
ret = (ret &lt; 0) ? 1 : -1;
return ret;
}
static void
custom_list_resort (CustomList *custom_list)
{
GtkTreePath *path;
gint *neworder, i;
g_return_if_fail ( custom_list != NULL );
g_return_if_fail ( CUSTOM_IS_LIST(custom_list) );
if (custom_list-&gt;sort_id == SORT_ID_NONE)
return;
if (custom_list-&gt;num_rows == 0)
return;
/* resort */
g_qsort_with_data(custom_list-&gt;rows,
custom_list-&gt;num_rows,
sizeof(CustomRecord*),
(GCompareDataFunc) custom_list_qsort_compare_func,
custom_list);
/* let other objects know about the new order */
neworder = g_new0(gint, custom_list-&gt;num_rows);
for (i = 0; i &lt; custom_list-&gt;num_rows; ++i)
{
/* Note that the API reference might be wrong about
* this, see bug number 124790 on bugs.gnome.org.
* Both will work, but one will give you 'jumpy'
* selections after row reordering. */
/* neworder[(custom_list-&gt;rows[i])-&gt;pos] = i; */
neworder[i] = (custom_list-&gt;rows[i])-&gt;pos;
(custom_list-&gt;rows[i])-&gt;pos = i;
}
path = gtk_tree_path_new();
gtk_tree_model_rows_reordered(GTK_TREE_MODEL(custom_list), path, NULL, neworder);
gtk_tree_path_free(path);
g_free(neworder);
}
</programlisting>
<para>
Finally, we should make sure that the model is resorted after we have inserted
a new row by adding a call to <literal>custom_list_resort</literal> to the end
of <literal>custom_list_append</literal>:
</para>
<programlisting role="C">
...
void
custom_list_append_record (CustomList *custom_list, const gchar *name, guint year_born)
{
...
custom_list_resort(custom_list);
}
</programlisting>
<para>
And that is it. Adding two calls to <literal>gtk_tree_view_column_set_sort_column_id</literal> in main.c
is left as yet another exercise for the reader.
</para>
<para>
If you are interested in seeing string sorting speed issues in action, you should modify main.c like this:
</para>
<programlisting role="C">
GtkWidget *
create_view_and_model (void)
{
gint i;
...
for (i=0; i &lt; 1000; ++i)
{
fill_model(customlist);
}
...
}
</programlisting>
<para>
Most likely, sorting 24000 rows by name will take up to several seconds now. Now, if you go back to
<literal>custom_list_compare_records</literal> and replace the call to <literal>g_utf8_collate</literal> with:
</para>
<programlisting role="C">
static gint
custom_list_compare_records (gint sort_id, CustomRecord *a, CustomRecord *b)
{
...
if ((a-&gt;name) &amp;&amp; (b-&gt;name))
return strcmp(a-&gt;name_collate_key,b-&gt;name_collate_key);
...
}
</programlisting>
<para>
... then you should hopefully register a dramatic speed increase when sorting by name.
</para>
</sect1>
<!-- ************************************************************** -->
<sect1 id="sec-custom-model-code">
<title>Working Example: Custom List Model Source Code</title>
<para>
Here is the complete source code for the custom list model presented
<link linkend="sec-custom-model-list">above</link>. Compile with:
</para>
<programlisting>
gcc -o customlist custom-list.c main.c `pkg-config --cflags --libs gtk+-2.0`
</programlisting>
<itemizedlist>
<listitem>
<para><link linkend="sec-custom-model-code-header">custom-list.h</link></para>
</listitem>
<listitem>
<para><link linkend="sec-custom-model-code-body">custom-list.c</link></para>
</listitem>
<listitem>
<para><link linkend="sec-custom-model-code-example">main.c</link></para>
</listitem>
</itemizedlist>
<!-- ************************************************************** -->
<sect2 id="sec-custom-model-code-header">
<title>custom-list.h</title>
<programlisting role="C">
#ifndef _custom_list_h_included_
#define _custom_list_h_included_
#include &lt;gtk/gtk.h&gt;
/* Some boilerplate GObject defines. 'klass' is used
* instead of 'class', because 'class' is a C++ keyword */
#define CUSTOM_TYPE_LIST (custom_list_get_type ())
#define CUSTOM_LIST(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), CUSTOM_TYPE_LIST, CustomList))
#define CUSTOM_LIST_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), CUSTOM_TYPE_LIST, CustomListClass))
#define CUSTOM_IS_LIST(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), CUSTOM_TYPE_LIST))
#define CUSTOM_IS_LIST_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), CUSTOM_TYPE_LIST))
#define CUSTOM_LIST_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), CUSTOM_TYPE_LIST, CustomListClass))
/* The data columns that we export via the tree model interface */
enum
{
CUSTOM_LIST_COL_RECORD = 0,
CUSTOM_LIST_COL_NAME,
CUSTOM_LIST_COL_YEAR_BORN,
CUSTOM_LIST_N_COLUMNS,
} ;
typedef struct _CustomRecord CustomRecord;
typedef struct _CustomList CustomList;
typedef struct _CustomListClass CustomListClass;
/* CustomRecord: this structure represents a row */
struct _CustomRecord
{
/* data - you can extend this */
gchar *name;
gchar *name_collate_key;
guint year_born;
/* admin stuff used by the custom list model */
guint pos; /* pos within the array */
};
/* CustomList: this structure contains everything we need for our
* model implementation. You can add extra fields to
* this structure, e.g. hashtables to quickly lookup
* rows or whatever else you might need, but it is
* crucial that 'parent' is the first member of the
* structure. */
struct _CustomList
{
GObject parent; /* this MUST be the first member */
guint num_rows; /* number of rows that we have */
CustomRecord **rows; /* a dynamically allocated array of pointers to
* the CustomRecord structure for each row */
/* These two fields are not absolutely necessary, but they */
/* speed things up a bit in our get_value implementation */
gint n_columns;
GType column_types[CUSTOM_LIST_N_COLUMNS];
gint stamp; /* Random integer to check whether an iter belongs to our model */
};
/* CustomListClass: more boilerplate GObject stuff */
struct _CustomListClass
{
GObjectClass parent_class;
};
GType custom_list_get_type (void);
CustomList *custom_list_new (void);
void custom_list_append_record (CustomList *custom_list,
const gchar *name,
guint year_born);
#endif /* _custom_list_h_included_ */
</programlisting>
<itemizedlist>
<listitem>
<para><link linkend="sec-custom-model-code-header">custom-list.h</link></para>
</listitem>
<listitem>
<para><link linkend="sec-custom-model-code-body">custom-list.c</link></para>
</listitem>
<listitem>
<para><link linkend="sec-custom-model-code-example">main.c</link></para>
</listitem>
</itemizedlist>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-custom-model-code-body">
<title>custom-list.c</title>
<programlisting role="C">
#include "custom-list.h"
/* boring declarations of local functions */
static void custom_list_init (CustomList *pkg_tree);
static void custom_list_class_init (CustomListClass *klass);
static void custom_list_tree_model_init (GtkTreeModelIface *iface);
static void custom_list_finalize (GObject *object);
static GtkTreeModelFlags custom_list_get_flags (GtkTreeModel *tree_model);
static gint custom_list_get_n_columns (GtkTreeModel *tree_model);
static GType custom_list_get_column_type (GtkTreeModel *tree_model,
gint index);
static gboolean custom_list_get_iter (GtkTreeModel *tree_model,
GtkTreeIter *iter,
GtkTreePath *path);
static GtkTreePath *custom_list_get_path (GtkTreeModel *tree_model,
GtkTreeIter *iter);
static void custom_list_get_value (GtkTreeModel *tree_model,
GtkTreeIter *iter,
gint column,
GValue *value);
static gboolean custom_list_iter_next (GtkTreeModel *tree_model,
GtkTreeIter *iter);
static gboolean custom_list_iter_children (GtkTreeModel *tree_model,
GtkTreeIter *iter,
GtkTreeIter *parent);
static gboolean custom_list_iter_has_child (GtkTreeModel *tree_model,
GtkTreeIter *iter);
static gint custom_list_iter_n_children (GtkTreeModel *tree_model,
GtkTreeIter *iter);
static gboolean custom_list_iter_nth_child (GtkTreeModel *tree_model,
GtkTreeIter *iter,
GtkTreeIter *parent,
gint n);
static gboolean custom_list_iter_parent (GtkTreeModel *tree_model,
GtkTreeIter *iter,
GtkTreeIter *child);
static GObjectClass *parent_class = NULL; /* GObject stuff - nothing to worry about */
/*****************************************************************************
*
* custom_list_get_type: here we register our new type and its interfaces
* with the type system. If you want to implement
* additional interfaces like GtkTreeSortable, you
* will need to do it here.
*
*****************************************************************************/
GType
custom_list_get_type (void)
{
static GType custom_list_type = 0;
if (custom_list_type)
return custom_list_type;
/* Some boilerplate type registration stuff */
if (1)
{
static const GTypeInfo custom_list_info =
{
sizeof (CustomListClass),
NULL, /* base_init */
NULL, /* base_finalize */
(GClassInitFunc) custom_list_class_init,
NULL, /* class finalize */
NULL, /* class_data */
sizeof (CustomList),
0, /* n_preallocs */
(GInstanceInitFunc) custom_list_init
};
custom_list_type = g_type_register_static (G_TYPE_OBJECT, "CustomList",
&amp;custom_list_info, (GTypeFlags)0);
}
/* Here we register our GtkTreeModel interface with the type system */
if (1)
{
static const GInterfaceInfo tree_model_info =
{
(GInterfaceInitFunc) custom_list_tree_model_init,
NULL,
NULL
};
g_type_add_interface_static (custom_list_type, GTK_TYPE_TREE_MODEL, &amp;tree_model_info);
}
return custom_list_type;
}
/*****************************************************************************
*
* custom_list_class_init: more boilerplate GObject/GType stuff.
* Init callback for the type system,
* called once when our new class is created.
*
*****************************************************************************/
static void
custom_list_class_init (CustomListClass *klass)
{
GObjectClass *object_class;
parent_class = (GObjectClass*) g_type_class_peek_parent (klass);
object_class = (GObjectClass*) klass;
object_class-&gt;finalize = custom_list_finalize;
}
/*****************************************************************************
*
* custom_list_tree_model_init: init callback for the interface registration
* in custom_list_get_type. Here we override
* the GtkTreeModel interface functions that
* we implement.
*
*****************************************************************************/
static void
custom_list_tree_model_init (GtkTreeModelIface *iface)
{
iface-&gt;get_flags = custom_list_get_flags;
iface-&gt;get_n_columns = custom_list_get_n_columns;
iface-&gt;get_column_type = custom_list_get_column_type;
iface-&gt;get_iter = custom_list_get_iter;
iface-&gt;get_path = custom_list_get_path;
iface-&gt;get_value = custom_list_get_value;
iface-&gt;iter_next = custom_list_iter_next;
iface-&gt;iter_children = custom_list_iter_children;
iface-&gt;iter_has_child = custom_list_iter_has_child;
iface-&gt;iter_n_children = custom_list_iter_n_children;
iface-&gt;iter_nth_child = custom_list_iter_nth_child;
iface-&gt;iter_parent = custom_list_iter_parent;
}
/*****************************************************************************
*
* custom_list_init: this is called everytime a new custom list object
* instance is created (we do that in custom_list_new).
* Initialise the list structure's fields here.
*
*****************************************************************************/
static void
custom_list_init (CustomList *custom_list)
{
custom_list-&gt;n_columns = CUSTOM_LIST_N_COLUMNS;
custom_list-&gt;column_types[0] = G_TYPE_POINTER; /* CUSTOM_LIST_COL_RECORD */
custom_list-&gt;column_types[1] = G_TYPE_STRING; /* CUSTOM_LIST_COL_NAME */
custom_list-&gt;column_types[2] = G_TYPE_UINT; /* CUSTOM_LIST_COL_YEAR_BORN */
g_assert (CUSTOM_LIST_N_COLUMNS == 3);
custom_list-&gt;num_rows = 0;
custom_list-&gt;rows = NULL;
custom_list-&gt;stamp = g_random_int(); /* Random int to check whether an iter belongs to our model */
}
/*****************************************************************************
*
* custom_list_finalize: this is called just before a custom list is
* destroyed. Free dynamically allocated memory here.
*
*****************************************************************************/
static void
custom_list_finalize (GObject *object)
{
/* CustomList *custom_list = CUSTOM_LIST(object); */
/* free all records and free all memory used by the list */
#warning IMPLEMENT
/* must chain up - finalize parent */
(* parent_class-&gt;finalize) (object);
}
/*****************************************************************************
*
* custom_list_get_flags: tells the rest of the world whether our tree model
* has any special characteristics. In our case,
* we have a list model (instead of a tree), and each
* tree iter is valid as long as the row in question
* exists, as it only contains a pointer to our struct.
*
*****************************************************************************/
static GtkTreeModelFlags
custom_list_get_flags (GtkTreeModel *tree_model)
{
g_return_val_if_fail (CUSTOM_IS_LIST(tree_model), (GtkTreeModelFlags)0);
return (GTK_TREE_MODEL_LIST_ONLY | GTK_TREE_MODEL_ITERS_PERSIST);
}
/*****************************************************************************
*
* custom_list_get_n_columns: tells the rest of the world how many data
* columns we export via the tree model interface
*
*****************************************************************************/
static gint
custom_list_get_n_columns (GtkTreeModel *tree_model)
{
g_return_val_if_fail (CUSTOM_IS_LIST(tree_model), 0);
return CUSTOM_LIST(tree_model)-&gt;n_columns;
}
/*****************************************************************************
*
* custom_list_get_column_type: tells the rest of the world which type of
* data an exported model column contains
*
*****************************************************************************/
static GType
custom_list_get_column_type (GtkTreeModel *tree_model,
gint index)
{
g_return_val_if_fail (CUSTOM_IS_LIST(tree_model), G_TYPE_INVALID);
g_return_val_if_fail (index &lt; CUSTOM_LIST(tree_model)-&gt;n_columns &amp;&amp; index &gt;= 0, G_TYPE_INVALID);
return CUSTOM_LIST(tree_model)-&gt;column_types[index];
}
/*****************************************************************************
*
* custom_list_get_iter: converts a tree path (physical position) into a
* tree iter structure (the content of the iter
* fields will only be used internally by our model).
* We simply store a pointer to our CustomRecord
* structure that represents that row in the tree iter.
*
*****************************************************************************/
static gboolean
custom_list_get_iter (GtkTreeModel *tree_model,
GtkTreeIter *iter,
GtkTreePath *path)
{
CustomList *custom_list;
CustomRecord *record;
gint *indices, n, depth;
g_assert(CUSTOM_IS_LIST(tree_model));
g_assert(path!=NULL);
custom_list = CUSTOM_LIST(tree_model);
indices = gtk_tree_path_get_indices(path);
depth = gtk_tree_path_get_depth(path);
/* we do not allow children */
g_assert(depth == 1); /* depth 1 = top level; a list only has top level nodes and no children */
n = indices[0]; /* the n-th top level row */
if ( n &gt;= custom_list-&gt;num_rows || n &lt; 0 )
return FALSE;
record = custom_list-&gt;rows[n];
g_assert(record != NULL);
g_assert(record-&gt;pos == n);
/* We simply store a pointer to our custom record in the iter */
iter-&gt;stamp = custom_list-&gt;stamp;
iter-&gt;user_data = record;
iter-&gt;user_data2 = NULL; /* unused */
iter-&gt;user_data3 = NULL; /* unused */
return TRUE;
}
/*****************************************************************************
*
* custom_list_get_path: converts a tree iter into a tree path (ie. the
* physical position of that row in the list).
*
*****************************************************************************/
static GtkTreePath *
custom_list_get_path (GtkTreeModel *tree_model,
GtkTreeIter *iter)
{
GtkTreePath *path;
CustomRecord *record;
CustomList *custom_list;
g_return_val_if_fail (CUSTOM_IS_LIST(tree_model), NULL);
g_return_val_if_fail (iter != NULL, NULL);
g_return_val_if_fail (iter-&gt;user_data != NULL, NULL);
custom_list = CUSTOM_LIST(tree_model);
record = (CustomRecord*) iter-&gt;user_data;
path = gtk_tree_path_new();
gtk_tree_path_append_index(path, record-&gt;pos);
return path;
}
/*****************************************************************************
*
* custom_list_get_value: Returns a row's exported data columns
* (_get_value is what gtk_tree_model_get uses)
*
*****************************************************************************/
static void
custom_list_get_value (GtkTreeModel *tree_model,
GtkTreeIter *iter,
gint column,
GValue *value)
{
CustomRecord *record;
CustomList *custom_list;
g_return_if_fail (CUSTOM_IS_LIST (tree_model));
g_return_if_fail (iter != NULL);
g_return_if_fail (column &lt; CUSTOM_LIST(tree_model)-&gt;n_columns);
g_value_init (value, CUSTOM_LIST(tree_model)-&gt;column_types[column]);
custom_list = CUSTOM_LIST(tree_model);
record = (CustomRecord*) iter-&gt;user_data;
g_return_if_fail ( record != NULL );
if(record-&gt;pos &gt;= custom_list-&gt;num_rows)
g_return_if_reached();
switch(column)
{
case CUSTOM_LIST_COL_RECORD:
g_value_set_pointer(value, record);
break;
case CUSTOM_LIST_COL_NAME:
g_value_set_string(value, record-&gt;name);
break;
case CUSTOM_LIST_COL_YEAR_BORN:
g_value_set_uint(value, record-&gt;year_born);
break;
}
}
/*****************************************************************************
*
* custom_list_iter_next: Takes an iter structure and sets it to point
* to the next row.
*
*****************************************************************************/
static gboolean
custom_list_iter_next (GtkTreeModel *tree_model,
GtkTreeIter *iter)
{
CustomRecord *record, *nextrecord;
CustomList *custom_list;
g_return_val_if_fail (CUSTOM_IS_LIST (tree_model), FALSE);
if (iter == NULL || iter-&gt;user_data == NULL)
return FALSE;
custom_list = CUSTOM_LIST(tree_model);
record = (CustomRecord *) iter-&gt;user_data;
/* Is this the last record in the list? */
if ((record-&gt;pos + 1) &gt;= custom_list-&gt;num_rows)
return FALSE;
nextrecord = custom_list-&gt;rows[(record-&gt;pos + 1)];
g_assert ( nextrecord != NULL );
g_assert ( nextrecord-&gt;pos == (record-&gt;pos + 1) );
iter-&gt;stamp = custom_list-&gt;stamp;
iter-&gt;user_data = nextrecord;
return TRUE;
}
/*****************************************************************************
*
* custom_list_iter_children: Returns TRUE or FALSE depending on whether
* the row specified by 'parent' has any children.
* If it has children, then 'iter' is set to
* point to the first child. Special case: if
* 'parent' is NULL, then the first top-level
* row should be returned if it exists.
*
*****************************************************************************/
static gboolean
custom_list_iter_children (GtkTreeModel *tree_model,
GtkTreeIter *iter,
GtkTreeIter *parent)
{
CustomList *custom_list;
g_return_val_if_fail (parent == NULL || parent-&gt;user_data != NULL, FALSE);
/* this is a list, nodes have no children */
if (parent)
return FALSE;
/* parent == NULL is a special case; we need to return the first top-level row */
g_return_val_if_fail (CUSTOM_IS_LIST (tree_model), FALSE);
custom_list = CUSTOM_LIST(tree_model);
/* No rows =&gt; no first row */
if (custom_list-&gt;num_rows == 0)
return FALSE;
/* Set iter to first item in list */
iter-&gt;stamp = custom_list-&gt;stamp;
iter-&gt;user_data = custom_list-&gt;rows[0];
return TRUE;
}
/*****************************************************************************
*
* custom_list_iter_has_child: Returns TRUE or FALSE depending on whether
* the row specified by 'iter' has any children.
* We only have a list and thus no children.
*
*****************************************************************************/
static gboolean
custom_list_iter_has_child (GtkTreeModel *tree_model,
GtkTreeIter *iter)
{
return FALSE;
}
/*****************************************************************************
*
* custom_list_iter_n_children: Returns the number of children the row
* specified by 'iter' has. This is usually 0,
* as we only have a list and thus do not have
* any children to any rows. A special case is
* when 'iter' is NULL, in which case we need
* to return the number of top-level nodes,
* ie. the number of rows in our list.
*
*****************************************************************************/
static gint
custom_list_iter_n_children (GtkTreeModel *tree_model,
GtkTreeIter *iter)
{
CustomList *custom_list;
g_return_val_if_fail (CUSTOM_IS_LIST (tree_model), -1);
g_return_val_if_fail (iter == NULL || iter-&gt;user_data != NULL, FALSE);
custom_list = CUSTOM_LIST(tree_model);
/* special case: if iter == NULL, return number of top-level rows */
if (!iter)
return custom_list-&gt;num_rows;
return 0; /* otherwise, this is easy again for a list */
}
/*****************************************************************************
*
* custom_list_iter_nth_child: If the row specified by 'parent' has any
* children, set 'iter' to the n-th child and
* return TRUE if it exists, otherwise FALSE.
* A special case is when 'parent' is NULL, in
* which case we need to set 'iter' to the n-th
* row if it exists.
*
*****************************************************************************/
static gboolean
custom_list_iter_nth_child (GtkTreeModel *tree_model,
GtkTreeIter *iter,
GtkTreeIter *parent,
gint n)
{
CustomRecord *record;
CustomList *custom_list;
g_return_val_if_fail (CUSTOM_IS_LIST (tree_model), FALSE);
custom_list = CUSTOM_LIST(tree_model);
/* a list has only top-level rows */
if(parent)
return FALSE;
/* special case: if parent == NULL, set iter to n-th top-level row */
if( n &gt;= custom_list-&gt;num_rows )
return FALSE;
record = custom_list-&gt;rows[n];
g_assert( record != NULL );
g_assert( record-&gt;pos == n );
iter-&gt;stamp = custom_list-&gt;stamp;
iter-&gt;user_data = record;
return TRUE;
}
/*****************************************************************************
*
* custom_list_iter_parent: Point 'iter' to the parent node of 'child'. As
* we have a list and thus no children and no
* parents of children, we can just return FALSE.
*
*****************************************************************************/
static gboolean
custom_list_iter_parent (GtkTreeModel *tree_model,
GtkTreeIter *iter,
GtkTreeIter *child)
{
return FALSE;
}
/*****************************************************************************
*
* custom_list_new: This is what you use in your own code to create a
* new custom list tree model for you to use.
*
*****************************************************************************/
CustomList *
custom_list_new (void)
{
CustomList *newcustomlist;
newcustomlist = (CustomList*) g_object_new (CUSTOM_TYPE_LIST, NULL);
g_assert( newcustomlist != NULL );
return newcustomlist;
}
/*****************************************************************************
*
* custom_list_append_record: Empty lists are boring. This function can
* be used in your own code to add rows to the
* list. Note how we emit the "row-inserted"
* signal after we have appended the row
* internally, so the tree view and other
* interested objects know about the new row.
*
*****************************************************************************/
void
custom_list_append_record (CustomList *custom_list,
const gchar *name,
guint year_born)
{
GtkTreeIter iter;
GtkTreePath *path;
CustomRecord *newrecord;
gulong newsize;
guint pos;
g_return_if_fail (CUSTOM_IS_LIST(custom_list));
g_return_if_fail (name != NULL);
pos = custom_list-&gt;num_rows;
custom_list-&gt;num_rows++;
newsize = custom_list-&gt;num_rows * sizeof(CustomRecord*);
custom_list-&gt;rows = g_realloc(custom_list-&gt;rows, newsize);
newrecord = g_new0(CustomRecord, 1);
newrecord-&gt;name = g_strdup(name);
newrecord-&gt;name_collate_key = g_utf8_collate_key(name,-1); /* for fast sorting, used later */
newrecord-&gt;year_born = year_born;
custom_list-&gt;rows[pos] = newrecord;
newrecord-&gt;pos = pos;
/* inform the tree view and other interested objects
* (e.g. tree row references) that we have inserted
* a new row, and where it was inserted */
path = gtk_tree_path_new();
gtk_tree_path_append_index(path, newrecord-&gt;pos);
custom_list_get_iter(GTK_TREE_MODEL(custom_list), &amp;iter, path);
gtk_tree_model_row_inserted(GTK_TREE_MODEL(custom_list), path, &amp;iter);
gtk_tree_path_free(path);
}
</programlisting>
<itemizedlist>
<listitem>
<para><link linkend="sec-custom-model-code-header">custom-list.h</link></para>
</listitem>
<listitem>
<para><link linkend="sec-custom-model-code-body">custom-list.c</link></para>
</listitem>
<listitem>
<para><link linkend="sec-custom-model-code-example">main.c</link></para>
</listitem>
</itemizedlist>
</sect2>
<!-- ************************************************************** -->
<sect2 id="sec-custom-model-code-example">
<title>main.c</title>
<para>
The following couple of lines provide a working test case that makes use of our custom list. It
creates one of our custom lists, adds some records, and displays it in a tree view.
</para>
<programlisting role="C">
#include "custom-list.h"
#include &lt;stdlib.h&gt;
void
fill_model (CustomList *customlist)
{
const gchar *firstnames[] = { "Joe", "Jane", "William", "Hannibal", "Timothy", "Gargamel", NULL } ;
const gchar *surnames[] = { "Grokowich", "Twitch", "Borheimer", "Bork", NULL } ;
const gchar **fname, **sname;
for (sname = surnames; *sname != NULL; sname++)
{
for (fname = firstnames; *fname != NULL; fname++)
{
gchar *name = g_strdup_printf ("%s %s", *fname, *sname);
custom_list_append_record (customlist, name, 1900 + (guint) (103.0*rand()/(RAND_MAX+1900.0)));
g_free(name);
}
}
}
GtkWidget *
create_view_and_model (void)
{
GtkTreeViewColumn *col;
GtkCellRenderer *renderer;
CustomList *customlist;
GtkWidget *view;
customlist = custom_list_new();
fill_model(customlist);
view = gtk_tree_view_new_with_model(GTK_TREE_MODEL(customlist));
g_object_unref(customlist); /* destroy store automatically with view */
renderer = gtk_cell_renderer_text_new();
col = gtk_tree_view_column_new();
gtk_tree_view_column_pack_start (col, renderer, TRUE);
gtk_tree_view_column_add_attribute (col, renderer, "text", CUSTOM_LIST_COL_NAME);
gtk_tree_view_column_set_title (col, "Name");
gtk_tree_view_append_column(GTK_TREE_VIEW(view),col);
renderer = gtk_cell_renderer_text_new();
col = gtk_tree_view_column_new();
gtk_tree_view_column_pack_start (col, renderer, TRUE);
gtk_tree_view_column_add_attribute (col, renderer, "text", CUSTOM_LIST_COL_YEAR_BORN);
gtk_tree_view_column_set_title (col, "Year Born");
gtk_tree_view_append_column(GTK_TREE_VIEW(view),col);
return view;
}
int
main (int argc, char **argv)
{
GtkWidget *window, *view, *scrollwin;
gtk_init(&amp;argc,&amp;argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_default_size (GTK_WINDOW(window), 200, 400);
g_signal_connect(window, "delete_event", gtk_main_quit, NULL);
scrollwin = gtk_scrolled_window_new(NULL,NULL);
view = create_view_and_model();
gtk_container_add(GTK_CONTAINER(scrollwin), view);
gtk_container_add(GTK_CONTAINER(window), scrollwin);
gtk_widget_show_all(window);
gtk_main();
return 0;
}
</programlisting>
</sect2>
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-custom-cell-renderers">
<title>Writing Custom Cell Renderers</title>
<para>
The cell renderers that come with Gtk+ should be sufficient for most purposes,
but there might be occasions where you want to display something in a tree view
that you cannot display with the provided cell renderers, or where you want to
derive from one of the provided cell renderers to extend its functionality.
</para>
<para>
You can do this by writing a new object that derives from
<literal>GtkCellRenderer</literal> (or even one of the other cell renderers
if you just want to extend an existing one).
</para>
<para>
Three things you need to do in the course of that:
</para>
<itemizedlist>
<listitem>
<para>
Register some new properties that your renderer needs with the type
system and write your own <literal>set_property</literal> and
<literal>get_property</literal> functions to set and get your new
renderer's properties.
</para>
</listitem>
<listitem>
<para>
Write your own <literal>cell_renderer_get_size</literal> function and
override the parent object's function (usually the parent is of type
<literal>GtkCellRenderer</literal>. Note that you should honour the
standard properties for padding and cell alignment of the parent
object here.
</para>
</listitem>
<listitem>
<para>
Write your own <literal>cell_renderer_render</literal> function and
override the parent object's function. This function does
the actual rendering.
</para>
</listitem>
</itemizedlist>
<para>
The GObject type system stuff of writing a new cell renderer is similar to
what we have done above when writing a custom tree model, and is relatively
straight forward in this case. Copy and paste and modify according to your
own needs.
</para>
<para>
Good examples of cell renderer code to look at or even modify are
<literal>GtkCellRendererPixbuf</literal> and <literal>GtkCellRendererToggle</literal>
in the Gtk+ source code tree. Both cases are less than five hundred lines
of code to look at and thus should be fairly easy to digest.
</para>
<sect1 id="sec-custom-cell-renderer-example">
<title>Working Example: a Progress Bar Cell Renderer</title>
<para>
In the following we will write a custom cell renderer to render progress bars
into a tree view (the code was "heavily inspired" by Sean Egan's progress bar
cell renderer implementation in GAIM):
</para>
<itemizedlist>
<listitem>
<para><link linkend="sec-custom-cell-renderer-example-header">custom-cell-renderer-progressbar.h</link></para>
</listitem>
<listitem>
<para><link linkend="sec-custom-cell-renderer-example-body">custom-cell-renderer-progressbar.c</link></para>
</listitem>
<listitem>
<para><link linkend="sec-custom-cell-renderer-example-test">main.c</link></para>
</listitem>
</itemizedlist>
<sect2 id="sec-custom-cell-renderer-example-header">
<title>custom-cell-renderer-progressbar.h</title>
<para>
The header file consists of the usual GObject type cast and type check defines
and our <literal>CustomCellRendererProgress</literal> structure. As the type
of the parent indicates, we derive from <literal>GtkCellRenderer</literal>. The
parent object must always be the first item in the structure (note also that it
is not a pointer to an object, but the parent object structure itself embedded
in our structure).
</para>
<para>
Our <literal>CustomCellRendererProgress</literal> structure is fairly uneventful
and contains only a double precision float variable in which we store our new
<literal>"percentage"</literal> property (which will determine how long the
progressbar is going to be).
</para>
<programlisting role="C">
#ifndef _custom_cell_renderer_progressbar_included_
#define _custom_cell_renderer_progressbar_included_
#include &lt;gtk/gtk.h&gt;
/* Some boilerplate GObject type check and type cast macros.
* 'klass' is used here instead of 'class', because 'class'
* is a c++ keyword */
#define CUSTOM_TYPE_CELL_RENDERER_PROGRESS (custom_cell_renderer_progress_get_type())
#define CUSTOM_CELL_RENDERER_PROGRESS(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj), CUSTOM_TYPE_CELL_RENDERER_PROGRESS, CustomCellRendererProgress))
#define CUSTOM_CELL_RENDERER_PROGRESS_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST ((klass), CUSTOM_TYPE_CELL_RENDERER_PROGRESS, CustomCellRendererProgressClass))
#define CUSTOM_IS_CELL_PROGRESS_PROGRESS(obj) (G_TYPE_CHECK_INSTANCE_TYPE ((obj), CUSTOM_TYPE_CELL_RENDERER_PROGRESS))
#define CUSTOM_IS_CELL_PROGRESS_PROGRESS_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass), CUSTOM_TYPE_CELL_RENDERER_PROGRESS))
#define CUSTOM_CELL_RENDERER_PROGRESS_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS ((obj), CUSTOM_TYPE_CELL_RENDERER_PROGRESS, CustomCellRendererProgressClass))
typedef struct _CustomCellRendererProgress CustomCellRendererProgress;
typedef struct _CustomCellRendererProgressClass CustomCellRendererProgressClass;
/* CustomCellRendererProgress: Our custom cell renderer
* structure. Extend according to need */
struct _CustomCellRendererProgress
{
GtkCellRenderer parent;
gdouble progress;
};
struct _CustomCellRendererProgressClass
{
GtkCellRendererClass parent_class;
};
GType custom_cell_renderer_progress_get_type (void);
GtkCellRenderer *custom_cell_renderer_progress_new (void);
#endif /* _custom_cell_renderer_progressbar_included_ */
</programlisting>
</sect2>
<sect2 id="sec-custom-cell-renderer-example-body">
<title>custom-cell-renderer-progressbar.c</title>
<para>
The code contains everything as described above, so let's jump right into it:
</para>
<programlisting role="C">
#include &quot;custom-cell-renderer-progressbar.h&quot;
/* This is based mainly on GtkCellRendererProgress
* in GAIM, written and (c) 2002 by Sean Egan
* (Licensed under the GPL), which in turn is
* based on Gtk&apos;s GtkCellRenderer[Text|Toggle|Pixbuf]
* implementation by Jonathan Blandford */
/* Some boring function declarations: GObject type system stuff */
static void custom_cell_renderer_progress_init (CustomCellRendererProgress *cellprogress);
static void custom_cell_renderer_progress_class_init (CustomCellRendererProgressClass *klass);
static void custom_cell_renderer_progress_get_property (GObject *object,
guint param_id,
GValue *value,
GParamSpec *pspec);
static void custom_cell_renderer_progress_set_property (GObject *object,
guint param_id,
const GValue *value,
GParamSpec *pspec);
static void custom_cell_renderer_progress_finalize (GObject *gobject);
/* These functions are the heart of our custom cell renderer: */
static void custom_cell_renderer_progress_get_size (GtkCellRenderer *cell,
GtkWidget *widget,
GdkRectangle *cell_area,
gint *x_offset,
gint *y_offset,
gint *width,
gint *height);
static void custom_cell_renderer_progress_render (GtkCellRenderer *cell,
GdkWindow *window,
GtkWidget *widget,
GdkRectangle *background_area,
GdkRectangle *cell_area,
GdkRectangle *expose_area,
guint flags);
enum
{
PROP_PERCENTAGE = 1,
};
static gpointer parent_class;
/***************************************************************************
*
* custom_cell_renderer_progress_get_type: here we register our type with
* the GObject type system if we
* haven&apos;t done so yet. Everything
* else is done in the callbacks.
*
***************************************************************************/
GType
custom_cell_renderer_progress_get_type (void)
{
static GType cell_progress_type = 0;
if (cell_progress_type)
return cell_progress_type;
if (1)
{
static const GTypeInfo cell_progress_info =
{
sizeof (CustomCellRendererProgressClass),
NULL, /* base_init */
NULL, /* base_finalize */
(GClassInitFunc) custom_cell_renderer_progress_class_init,
NULL, /* class_finalize */
NULL, /* class_data */
sizeof (CustomCellRendererProgress),
0, /* n_preallocs */
(GInstanceInitFunc) custom_cell_renderer_progress_init,
};
/* Derive from GtkCellRenderer */
cell_progress_type = g_type_register_static (GTK_TYPE_CELL_RENDERER,
&quot;CustomCellRendererProgress&quot;,
&amp;cell_progress_info,
0);
}
return cell_progress_type;
}
/***************************************************************************
*
* custom_cell_renderer_progress_init: set some default properties of the
* parent (GtkCellRenderer).
*
***************************************************************************/
static void
custom_cell_renderer_progress_init (CustomCellRendererProgress *cellrendererprogress)
{
GTK_CELL_RENDERER(cellrendererprogress)-&gt;mode = GTK_CELL_RENDERER_MODE_INERT;
GTK_CELL_RENDERER(cellrendererprogress)-&gt;xpad = 2;
GTK_CELL_RENDERER(cellrendererprogress)-&gt;ypad = 2;
}
/***************************************************************************
*
* custom_cell_renderer_progress_class_init:
*
* set up our own get_property and set_property functions, and
* override the parent&apos;s functions that we need to implement.
* And make our new &quot;percentage&quot; property known to the type system.
* If you want cells that can be activated on their own (ie. not
* just the whole row selected) or cells that are editable, you
* will need to override &apos;activate&apos; and &apos;start_editing&apos; as well.
*
***************************************************************************/
static void
custom_cell_renderer_progress_class_init (CustomCellRendererProgressClass *klass)
{
GtkCellRendererClass *cell_class = GTK_CELL_RENDERER_CLASS(klass);
GObjectClass *object_class = G_OBJECT_CLASS(klass);
parent_class = g_type_class_peek_parent (klass);
object_class-&gt;finalize = custom_cell_renderer_progress_finalize;
/* Hook up functions to set and get our
* custom cell renderer properties */
object_class-&gt;get_property = custom_cell_renderer_progress_get_property;
object_class-&gt;set_property = custom_cell_renderer_progress_set_property;
/* Override the two crucial functions that are the heart
* of a cell renderer in the parent class */
cell_class-&gt;get_size = custom_cell_renderer_progress_get_size;
cell_class-&gt;render = custom_cell_renderer_progress_render;
/* Install our very own properties */
g_object_class_install_property (object_class,
PROP_PERCENTAGE,
g_param_spec_double (&quot;percentage&quot;,
&quot;Percentage&quot;,
&quot;The fractional progress to display&quot;,
0, 1, 0,
G_PARAM_READWRITE));
}
/***************************************************************************
*
* custom_cell_renderer_progress_finalize: free any resources here
*
***************************************************************************/
static void
custom_cell_renderer_progress_finalize (GObject *object)
{
/*
CustomCellRendererProgress *cellrendererprogress = CUSTOM_CELL_RENDERER_PROGRESS(object);
*/
/* Free any dynamically allocated resources here */
(* G_OBJECT_CLASS (parent_class)-&gt;finalize) (object);
}
/***************************************************************************
*
* custom_cell_renderer_progress_get_property: as it says
*
***************************************************************************/
static void
custom_cell_renderer_progress_get_property (GObject *object,
guint param_id,
GValue *value,
GParamSpec *psec)
{
CustomCellRendererProgress *cellprogress = CUSTOM_CELL_RENDERER_PROGRESS(object);
switch (param_id)
{
case PROP_PERCENTAGE:
g_value_set_double(value, cellprogress-&gt;progress);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, param_id, psec);
break;
}
}
/***************************************************************************
*
* custom_cell_renderer_progress_set_property: as it says
*
***************************************************************************/
static void
custom_cell_renderer_progress_set_property (GObject *object,
guint param_id,
const GValue *value,
GParamSpec *pspec)
{
CustomCellRendererProgress *cellprogress = CUSTOM_CELL_RENDERER_PROGRESS (object);
switch (param_id)
{
case PROP_PERCENTAGE:
cellprogress-&gt;progress = g_value_get_double(value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID(object, param_id, pspec);
break;
}
}
/***************************************************************************
*
* custom_cell_renderer_progress_new: return a new cell renderer instance
*
***************************************************************************/
GtkCellRenderer *
custom_cell_renderer_progress_new (void)
{
return g_object_new(CUSTOM_TYPE_CELL_RENDERER_PROGRESS, NULL);
}
/***************************************************************************
*
* custom_cell_renderer_progress_get_size: crucial - calculate the size
* of our cell, taking into account
* padding and alignment properties
* of parent.
*
***************************************************************************/
#define FIXED_WIDTH 100
#define FIXED_HEIGHT 10
static void
custom_cell_renderer_progress_get_size (GtkCellRenderer *cell,
GtkWidget *widget,
GdkRectangle *cell_area,
gint *x_offset,
gint *y_offset,
gint *width,
gint *height)
{
gint calc_width;
gint calc_height;
calc_width = (gint) cell-&gt;xpad * 2 + FIXED_WIDTH;
calc_height = (gint) cell-&gt;ypad * 2 + FIXED_HEIGHT;
if (width)
*width = calc_width;
if (height)
*height = calc_height;
if (cell_area)
{
if (x_offset)
{
*x_offset = cell-&gt;xalign * (cell_area-&gt;width - calc_width);
*x_offset = MAX (*x_offset, 0);
}
if (y_offset)
{
*y_offset = cell-&gt;yalign * (cell_area-&gt;height - calc_height);
*y_offset = MAX (*y_offset, 0);
}
}
}99
/***************************************************************************
*
* custom_cell_renderer_progress_render: crucial - do the rendering.
*
***************************************************************************/
static void
custom_cell_renderer_progress_render (GtkCellRenderer *cell,
GdkWindow *window,
GtkWidget *widget,
GdkRectangle *background_area,
GdkRectangle *cell_area,
GdkRectangle *expose_area,
guint flags)
{
CustomCellRendererProgress *cellprogress = CUSTOM_CELL_RENDERER_PROGRESS (cell);
GtkStateType state;
gint width, height;
gint x_offset, y_offset;
custom_cell_renderer_progress_get_size (cell, widget, cell_area,
&amp;x_offset, &amp;y_offset,
&amp;width, &amp;height);
if (GTK_WIDGET_HAS_FOCUS (widget))
state = GTK_STATE_ACTIVE;
else
state = GTK_STATE_NORMAL;
width -= cell-&gt;xpad*2;
height -= cell-&gt;ypad*2;
gtk_paint_box (widget-&gt;style,
window,
GTK_STATE_NORMAL, GTK_SHADOW_IN,
NULL, widget, &quot;trough&quot;,
cell_area-&gt;x + x_offset + cell-&gt;xpad,
cell_area-&gt;y + y_offset + cell-&gt;ypad,
width - 1, height - 1);
gtk_paint_box (widget-&gt;style,
window,
state, GTK_SHADOW_OUT,
NULL, widget, &quot;bar&quot;,
cell_area-&gt;x + x_offset + cell-&gt;xpad,
cell_area-&gt;y + y_offset + cell-&gt;ypad,
width * cellprogress-&gt;progress,
height - 1);
}
</programlisting>
</sect2>
<sect2 id="sec-custom-cell-renderer-example-test">
<title>main.c</title>
<para>
And here is a little test that makes use of our new <literal>CustomCellRendererProgress</literal>:
</para>
<programlisting role="C">
#include &quot;custom-cell-renderer-progressbar.h&quot;
static GtkListStore *liststore;
static gboolean increasing = TRUE; /* direction of progress bar change */
enum
{
COL_PERCENTAGE = 0,
COL_TEXT,
NUM_COLS
};
#define STEP 0.01
gboolean
increase_progress_timeout (GtkCellRenderer *renderer)
{
GtkTreeIter iter;
gfloat perc = 0.0;
gchar buf[20];
gtk_tree_model_get_iter_first(GTK_TREE_MODEL(liststore), &amp;iter); /* first and only row */
gtk_tree_model_get (GTK_TREE_MODEL(liststore), &amp;iter, COL_PERCENTAGE, &amp;perc, -1);
if ( perc &gt; (1.0-STEP) || (perc &lt; STEP &amp;&amp; perc &gt; 0.0) )
{
increasing = (!increasing);
}
if (increasing)
perc = perc + STEP;
else
perc = perc - STEP;
g_snprintf(buf, sizeof(buf), &quot;%u %%&quot;, (guint)(perc*100));
gtk_list_store_set (liststore, &amp;iter, COL_PERCENTAGE, perc, COL_TEXT, buf, -1);
return TRUE; /* Call again */
}
GtkWidget *
create_view_and_model (void)
{
GtkTreeViewColumn *col;
GtkCellRenderer *renderer;
GtkTreeIter iter;
GtkWidget *view;
liststore = gtk_list_store_new(NUM_COLS, G_TYPE_FLOAT, G_TYPE_STRING);
gtk_list_store_append(liststore, &amp;iter);
gtk_list_store_set (liststore, &amp;iter, COL_PERCENTAGE, 0.5, -1); /* start at 50% */
view = gtk_tree_view_new_with_model(GTK_TREE_MODEL(liststore));
g_object_unref(liststore); /* destroy store automatically with view */
renderer = gtk_cell_renderer_text_new();
col = gtk_tree_view_column_new();
gtk_tree_view_column_pack_start (col, renderer, TRUE);
gtk_tree_view_column_add_attribute (col, renderer, &quot;text&quot;, COL_TEXT);
gtk_tree_view_column_set_title (col, &quot;Progress&quot;);
gtk_tree_view_append_column(GTK_TREE_VIEW(view),col);
renderer = custom_cell_renderer_progress_new();
col = gtk_tree_view_column_new();
gtk_tree_view_column_pack_start (col, renderer, TRUE);
gtk_tree_view_column_add_attribute (col, renderer, &quot;percentage&quot;, COL_PERCENTAGE);
gtk_tree_view_column_set_title (col, &quot;Progress&quot;);
gtk_tree_view_append_column(GTK_TREE_VIEW(view),col);
g_timeout_add(50, (GSourceFunc) increase_progress_timeout, NULL);
return view;
}
int
main (int argc, char **argv)
{
GtkWidget *window, *view;
gtk_init(&amp;argc,&amp;argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_default_size (GTK_WINDOW(window), 150, 100);
g_signal_connect(window, &quot;delete_event&quot;, gtk_main_quit, NULL);
view = create_view_and_model();
gtk_container_add(GTK_CONTAINER(window), view);
gtk_widget_show_all(window);
gtk_main();
return 0;
}
</programlisting>
</sect2>
</sect1>
<sect1 id="sec-custom-cell-renderers-external">
<title>Cell Renderers Others Have Written</title>
<para>
Just in case you are one of those people who do not
like to re-invent the wheel, here is a list of custom
cell renderers other people have written:
</para>
<itemizedlist>
<listitem>
<para>
<ulink url="http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/gaim/gaim/src/gtkcellrendererprogress.c">Progress bar cell renderer</ulink> (gaim)
</para>
</listitem>
<listitem>
<para>
<ulink url="http://cvs.gnome.org/bonsai/cvsblame.cgi?file=mrproject%2Fsrc%2Fcell-renderers/mg-cell-renderer-date.c&amp;rev=&amp;root=/cvs/gnome">Date cell renderer</ulink> (mrproject) (is this one easy to re-use?)
</para>
</listitem>
<listitem>
<para>
<ulink url="http://cvs.gnome.org/bonsai/cvsblame.cgi?file=mrproject%2Fsrc%2Fcell-renderers/mg-cell-renderer-list.c&amp;rev=&amp;root=/cvs/gnome">List/combo cell renderer</ulink> (mrproject) (is this one easy to re-use?)
</para>
</listitem>
<listitem>
<para>
<ulink url="http://cvs.gnome.org/bonsai/cvsblame.cgi?file=mrproject%2Fsrc%2Fcell-renderers/mg-cell-renderer-popup.c&amp;rev=&amp;root=/cvs/gnome">Pop-up cell renderer</ulink> (mrproject) (what does this do?)
</para>
</listitem>
<listitem>
<para>
Your custom cell renderer here?!
</para>
</listitem>
</itemizedlist>
</sect1>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-other-info">
<title>Other Resources</title>
<para>
A short tutorial like this cannot possibly cover everything. Luckily,
there is a lot more information out there. Here is a list of links
that you might find useful (if you have any links that should appear
here as well, please send them to <literal>tim at centricular dot net</literal>).
</para>
<itemizedlist>
<listitem>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/gtk/index.html">Gtk+ API Reference Manual</ulink>
</para>
</listitem>
<listitem>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/gdk/index.html">Gdk API Reference Manual</ulink>
</para>
</listitem>
<listitem>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/pango/index.html">Pango API Reference Manual</ulink>
</para>
</listitem>
<listitem>
<para>
<ulink url="http://developer.gnome.org/doc/API/2.0/glib/index.html">GLib API Reference Manual</ulink>
</para>
</listitem>
<listitem>
<para>
<ulink url="http://mail.gnome.org/archives/gtk-app-devel-list/index.html">gtk-app-devel mailing list archives</ulink> - search them!
</para>
</listitem>
<listitem>
<para>
<ulink url="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk%2b/demos/gtk-demo">gtk-demo</ulink> -
part of the Gtk+ source code (look in gtk+-2.x.y/demos/gtk-demo), especially
<ulink url="http://cvs.gnome.org/bonsai/cvsblame.cgi?file=gtk%2B%2Fdemos%2Fgtk-demo/list_store.c&amp;rev=&amp;root=/cvs/gnome">list_store.c</ulink>,
<ulink url="http://cvs.gnome.org/bonsai/cvsblame.cgi?file=gtk%2B%2Fdemos%2Fgtk-demo/tree_store.c&amp;rev=&amp;root=/cvs/gnome">tree_store.c</ulink>, and
<ulink url="http://cvs.gnome.org/bonsai/cvsblame.cgi?file=gtk%2B%2Fdemos%2Fgtk-demo/stock_browser.c&amp;rev=&amp;root=/cvs/gnome">stock_browser.c</ulink>
</para>
</listitem>
<listitem>
<para>
<ulink url="http://www.gtkmm.org/gtkmm2/docs/tutorial/html/ch08.html">TreeView tutorial using Gtk's C++ interface (gtkmm)</ulink>
</para>
</listitem>
<listitem>
<para>
<ulink url="http://liw.iki.fi/liw/texts/gtktreeview-tutorial.html">TreeView tutorial using Gtk's python interface</ulink>
</para>
</listitem>
<listitem>
<para>
Some slides from Owen Taylor's GUADEC 2003 <ulink url="http://people.redhat.com/otaylor/tutorial/guadec2003/">tutorial</ulink>
(<ulink url="http://people.redhat.com/otaylor/tutorial/guadec2003/gtk-tut.ps">postscript</ulink>,
<ulink url="http://people.redhat.com/otaylor/tutorial/guadec2003/gtk-tut.pdf">pdf</ulink>, see pages 13-15)
</para>
</listitem>
<listitem>
<para>
<ulink url="http://www.gnome.org/softwaremap/">Existing applications</ulink> - yes, they exist, and <emphasis>you</emphasis>
can look at their source code. <ulink url="http://sourceforge.net/">SourceForge's</ulink> WebCVS browse feature is quite
useful, and the same goes for <ulink url="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome">GNOME</ulink> as well.
</para>
</listitem>
<listitem>
<para>
If your intention is to display external data (from a database, or in XML form) as a list or tree or table,
you might also be interested <ulink url="http://www.gnome-db.org/">GnomeDB</ulink>, especially
libgda and libgnomedb (e.g. the GnomeDBGrid widget). See also
<ulink url="ftp://kalamazoolinux.org/pub/pdf/dbaccess.pdf">this PDF presentation</ulink>
(page 24ff).
</para>
</listitem>
<listitem>
<para>
your link here!
</para>
</listitem>
</itemizedlist>
</chapter>
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<!-- ************************************************************** -->
<chapter id="sec-treeviewtut-license">
<title>Copyright, License, Credits, and Revision History</title>
<sect1 id="sec-treeviewtut-copyright-license">
<title>Copyright and License</title>
<para>
Copyright (c) 2003-2004 Tim-Philipp M&uuml;ller <email>tim at centricular dot net</email>
</para>
<para>
This tutorial may be redistributed and modified freely in any form, as
long as all authors are given due credit for their work and all non-trivial
changes by third parties are clearly marked as such either within the
document (e.g. in a revision history), or at an external and publicly
accessible place that is refered to in the document (e.g. a CVS repository).
</para>
</sect1>
<sect1 id="sec-treeviewtut-credits">
<title>Credits</title>
<para>
Thanks to Axel C. for proof-reading the first drafts, for many suggestions,
and for introducing me to the tree view widget in the first place (back then
when I was still convinced that porting to Gtk+-2.x was unnecessary, Gtk+-1.2
applications looked nice, and Aristotle had already said everything about
politics that needs to be said).
</para>
<para>
Harring Figueiredo <ulink url="http://mail.gnome.org/archives/gtk-app-devel-list/2003-September/msg00240.html">shed</ulink>
some light on how GtkListStore and GtkTreeStore deal with pixbufs.
</para>
<para>
Ken Rastatter <ulink url="http://mail.gnome.org/archives/gtk-app-devel-list/2003-September/msg00250.html">suggested</ulink>
some additional topics (with complete references even).
</para>
<para>
Both Andrej Prsa and Alan B. Canon sent me a couple of suggestions, and 'taf2', Massimo Mangoni and others spotted some typos.
</para>
<para>
Many thanks to all of them, and of course also to kris and everyone else
in #gtk+.
</para>
</sect1>
<sect1 id="sec-treeviewtut-history">
<title>Revision History</title>
<itemizedlist>
<title>
5th June 2005
</title>
<listitem>
<para>
Remove unnecessary col = gtk_tree_view_column_new() im hello world
code (leftover from migration to convenience functions).
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
3rd February 2005
</title>
<listitem>
<para>
Point out that GObjects such as GdkPixbufs retrieved with
gtk_tree_model_get() need to be g_object_unref()'ed after
use, as gtk_tree_model_get() adds a reference.
</para>
</listitem>
<listitem>
<para>
Added explicit (gint) event->x double to int conversion to
code snippet using gtk_tree_view_get_path_at_pos() to avoid
compiler warnings.
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
9th September 2004
</title>
<listitem>
<para>
Fixed another mistake in tree path explanation: text did not
correspond picture (s/movie clips/movie trailers/); (thanks
to Benjamin Brandt for spotting it).
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
6th August 2004
</title>
<listitem>
<para>
Fixed mistake in tree path explanation (s/4th/5th/)
(thanks to both Andrew Kirillov and Benjamin Brandt
for spotting it).
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
30th April 2004
</title>
<listitem>
<para>
Added Hello World
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
31st March 2004
</title>
<listitem>
<para>
Fixed fatal typo in custom list code: g_assert() in custom_list_init() should be ==, not !=
(spotted by mmc).
</para>
</listitem>
<listitem>
<para>
Added link to Owen Taylor's mail on the GtkTreeView Drag'n'Drop API.
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
24th January 2004
</title>
<listitem>
<para>
Fixed typo in code example (remove n-th row example)
(Thanks to roel for spotting it).
</para>
</listitem>
<listitem>
<para>
Changed 'Context menus' section title
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
19th January 2004
</title>
<listitem>
<para>
Expanded section on GtkTreeRowReferences, and on removing multiple rows.
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
8th January 2004
</title>
<listitem>
<para>
Added tiny section on Glade and treeviews
</para>
</listitem>
<listitem>
<para>
Added more detail to the section describing GtkTreePath, GtkTreeIter et.al.
</para>
</listitem>
<listitem>
<para>
Reformatted document structure: instead of one single chapter with lots
of sections, have multiple chapters (this tutorial is way to big to
become part of the Gtk+ tutorial anyway); enumerate chapters and sections.
</para>
</listitem>
<listitem>
<para>
Expanded the section on tree view columns and cell renderers, with help
of two diagrams by Owen Taylor (from the GUADEC 2003 Gtk+ tutorial slides).
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
10th December 2003
</title>
<listitem>
<para>
Added more information about how to remove a single row, or more specifically, the n-th row of a list store
</para>
</listitem>
<listitem>
<para>
Added a short example about how to pack icons into the tree view.
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
28th October 2003
</title>
<listitem>
<para>
Editable cells will work fine even if selection is set to GTK_SELECTION_NONE. Removed sentences that say otherwise.
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
23rd October 2003
</title>
<listitem>
<para>
fix 'jumpy' selections in custom model GtkTreeSortable interface implementation. gtk_tree_model_rows_reordered() does not
seem to work like the API reference implies (see <ulink url="http://bugs.gnome.org/show_bug.cgi?id=124790">bug #124790</ulink>)
</para>
</listitem>
<listitem>
<para>
added section about how to get the cell renderer a button click happened on
</para>
</listitem>
<listitem>
<para>
added section about editable cells with spin buttons (and a CellRendererSpin implementation to the examples)
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
10th October 2003
</title>
<listitem>
<para>
make custom model GtkTreeSortable implementation emit "sort-column-changed" signal when sortid is changed
</para>
</listitem>
<listitem>
<para>
fixed code typo in selection function section; added a paragraph about rule hint to 'make whole row coloured or bold' section
</para>
</listitem>
</itemizedlist>
<itemizedlist>
<title>
7th October 2003
</title>
<listitem>
<para>
Reformatted source code to make it fit on pages when generating ps/pdf output
</para>
</listitem>
<listitem>
<para>
Added link to PDF and docbook XML versions.
</para>
</listitem>
</itemizedlist>
</sect1>
</chapter>
</book>
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