Add the initial version of the water level widget

data/gwr-window.ui

@@ -1,19 +1,37 @@
 <?xml version="1.0" encoding="UTF-8"?>
+<!-- Generated with glade 3.22.0 -->
 <interface>
+  <requires lib="gtk+" version="3.10"/>
   <template class="GwrWindow" parent="GtkApplicationWindow">
-    <property name="default-width">600</property>
+    <property name="can_focus">False</property>
-    <property name="default-height">300</property>
+    <property name="default_width">600</property>
-    <child type="titlebar">
+    <property name="default_height">300</property>
-      <object class="GtkHeaderBar" id="header_bar">
-        <property name="visible">True</property>
-        <property name="show-close-button">True</property>
-        <property name="title">Water Reminder</property>
-      </object>
-    </child>
     <child>
       <object class="GwrWaterLevel" id="level">
         <property name="visible">True</property>
       </object>
     </child>
+    <child type="titlebar">
+      <object class="GtkHeaderBar" id="header_bar">
+        <property name="visible">True</property>
+        <property name="can_focus">False</property>
+        <property name="title">Water Reminder</property>
+        <property name="show_close_button">True</property>
+        <child>
+          <object class="GtkButton">
+            <property name="visible">True</property>
+            <property name="can_focus">True</property>
+            <property name="receives_default">True</property>
+            <child>
+              <object class="GtkImage">
+                <property name="visible">True</property>
+                <property name="can_focus">False</property>
+                <property name="icon_name">list-add-symbolic</property>
+              </object>
+            </child>
+          </object>
+        </child>
+      </object>
+    </child>
   </template>
 </interface>

src/gwr-water-level.c

@@ -2,24 +2,97 @@
 
 struct _GwrWaterLevel {
     GtkWidget parent_instance;
+
+    gfloat level;
 };
 
+/**
+ * GwrWaterLevel:
+ *
+ * A widget displaying a glass filled with water.
+ */
 G_DEFINE_TYPE(GwrWaterLevel, gwr_water_level, GTK_TYPE_WIDGET)
 
+enum {
+    PROP_0,
+    PROP_LEVEL,
+    N_PROPS
+};
+
+static GParamSpec *props[N_PROPS] = { NULL, };
+
+/**
+ * gwr_water_level_set_level:
+ * @self: a #GwrWaterLevel object
+ * @level: the level to set
+ *
+ * Set the water level for this object.
+ */
+void
+gwr_water_level_set_level(GwrWaterLevel *self,
+                          gfloat         level)
+{
+    self->level = MAX(0, MIN(level, 1.0));
+
+    g_object_notify_by_pspec(G_OBJECT(self), props[PROP_LEVEL]);
+}
+
+/**
+ * gwr_water_level_get_level:
+ * @self: a #GwrWaterLevel object
+ *
+ * @returns: the current water level
+ */
+gfloat
+gwr_water_level_get_level(GwrWaterLevel *self)
+{
+    return self->level;
+}
+
 static gboolean
 gwr_water_level_draw(GtkWidget *widget, cairo_t *cr)
 {
+    GwrWaterLevel *self = GWR_WATER_LEVEL(widget);
     GtkStyleContext *context = gtk_widget_get_style_context(widget);
     gint width = gtk_widget_get_allocated_width(widget);
     gint height = gtk_widget_get_allocated_height(widget);
     GdkRGBA color;
+    gint left, right;
 
     gtk_render_background(context, cr, 0, 0, width, height);
     gtk_render_frame(context, cr, 0, 0, width, height);
 
-  cairo_arc(cr, width / 2.0, height / 2.0, MIN(width, height) / 2.0, 0, 2 * G_PI);
+    left = right = width / 2.0;
+    left -= 3.0 * height / 8.0;
+    right += 3.0 * height / 8.0;
+    width = right - left;
+
+    cairo_save(cr);
+
+    gint top_left_x = left + (width * 0.1);
+    gint top_y = width * 0.1;
+    gint top_right_x = right - (width * 0.1);
+    gint bottom_right_x = right - (width * 0.2);
+    gint bottom_y = height - (width * 0.1);
+    gint bottom_left_x = left + (width * 0.2);
+    float level_y = top_y + (bottom_y - top_y) * (1.0 - self->level);
+
+    cairo_move_to(cr, top_left_x, top_y);
+    cairo_line_to(cr, top_right_x, top_y);
+    cairo_line_to(cr, bottom_right_x, bottom_y);
+    cairo_line_to(cr, bottom_left_x, bottom_y);
+    cairo_close_path(cr);
+    cairo_stroke(cr);
+
+    cairo_move_to(cr, bottom_right_x, bottom_y);
+    cairo_line_to(cr, bottom_left_x, bottom_y);
+    cairo_line_to(cr, bottom_left_x - ((top_right_x - bottom_right_x) * self->level), level_y);
+    cairo_line_to(cr, bottom_right_x + ((top_right_x - bottom_right_x) * self->level), level_y);
+    cairo_close_path(cr);
+    cairo_restore(cr);
+
     gtk_style_context_get_color(context, gtk_style_context_get_state(context), &color);
-  gdk_cairo_set_source_rgba(cr, &color);
+
     gdk_cairo_set_source_rgba(cr, &color);
     cairo_fill (cr);
 
@@ -44,17 +117,91 @@ gwr_water_level_destroy(GtkWidget *widget)
     GTK_WIDGET_CLASS(gwr_water_level_parent_class)->destroy(widget);
 }
 
+static void
+gwr_water_level_get_preferred_height(GtkWidget *widget, gint *minimum_height, gint *natural_height)
+{
+    if (minimum_height != NULL) {
+        *minimum_height = 200;
+    }
+
+    if (natural_height != NULL) {
+        *natural_height = 400;
+    }
+}
+
+static void
+gwr_water_level_get_preferred_width(GtkWidget *widget, gint *minimum_width, gint *natural_width)
+{
+    if (minimum_width != NULL) {
+        *minimum_width = 100;
+    }
+
+    if (natural_width != NULL) {
+        *natural_width = 200;
+    }
+}
+
+static void
+gwr_water_level_set_property(GObject      *gobject,
+                             guint         prop_id,
+                             const GValue *value,
+                             GParamSpec   *pspec)
+{
+    switch (prop_id) {
+    case PROP_LEVEL:
+        gwr_water_level_set_level(GWR_WATER_LEVEL(gobject), g_value_get_float(value));
+
+        break;
+    default:
+        G_OBJECT_WARN_INVALID_PROPERTY_ID(gobject, prop_id, pspec);
+
+        break;
+    }
+}
+
+static void
+gwr_water_level_get_property(GObject    *gobject,
+                             guint       prop_id,
+                             GValue     *value,
+                             GParamSpec *pspec)
+{
+    switch (prop_id) {
+    case PROP_LEVEL:
+        g_value_set_float(value, gwr_water_level_get_level(GWR_WATER_LEVEL(gobject)));
+
+        break;
+    default:
+        G_OBJECT_WARN_INVALID_PROPERTY_ID(gobject, prop_id, pspec);
+
+        break;
+    }
+}
+
 static void
 gwr_water_level_class_init(GwrWaterLevelClass *klass)
 {
     GObjectClass *gobject_class = G_OBJECT_CLASS(klass);
     GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
 
+    gobject_class->set_property = gwr_water_level_set_property;
+    gobject_class->get_property = gwr_water_level_get_property;
     gobject_class->finalize = gwr_water_level_finalize;
+
     widget_class->destroy = gwr_water_level_destroy;
+    widget_class->get_preferred_width = gwr_water_level_get_preferred_width;
+    widget_class->get_preferred_height = gwr_water_level_get_preferred_height;
     widget_class->draw = gwr_water_level_draw;
+
+    props[PROP_LEVEL] = g_param_spec_float(
+        "level", "level", "The current water level",
+        0.0, 1.0, 0.0,
+        G_PARAM_STATIC_STRINGS | G_PARAM_READWRITE);
+    g_object_class_install_properties(gobject_class, N_PROPS, props);
 }
 
  static void
 gwr_water_level_init(GwrWaterLevel *self)
-{}
+{
+    self->level = 0.0;
+    gtk_widget_set_has_window(GTK_WIDGET(self), FALSE);
+}

src/gwr-water-level.h

@@ -8,6 +8,10 @@ G_BEGIN_DECLS
 # define GWR_TYPE_WATER_LEVEL (gwr_water_level_get_type())
 G_DECLARE_FINAL_TYPE(GwrWaterLevel, gwr_water_level, GWR, WATER_LEVEL, GtkWidget)
 
+void gwr_water_level_set_level(GwrWaterLevel *water_level,
+                               gfloat         level);
+gfloat gwr_water_level_get_level(GwrWaterLevel *water_level);
+
 G_END_DECLS
 
 #endif  /* __GWR_WATER_LEVEL_H__ */

src/gwr-window.c

@@ -44,5 +44,7 @@ gwr_window_class_init (GwrWindowClass *klass)
 static void
 gwr_window_init (GwrWindow *self)
 {
+  g_type_ensure(GWR_TYPE_WATER_LEVEL);
+
   gtk_widget_init_template (GTK_WIDGET (self));
 }