GtkStyleContext: Add gtk_render_icon_pixbuf()

This function is similar to gtk_style_render_icon(), which is now
implemented on top of this one.

gtk/gtkthemingengine.c

@@ -168,6 +168,9 @@ static void gtk_theming_engine_render_activity  (GtkThemingEngine *engine,
                                                  gdouble           y,
                                                  gdouble           width,
                                                  gdouble           height);
+static GdkPixbuf * gtk_theming_engine_render_icon_pixbuf (GtkThemingEngine    *engine,
+                                                          const GtkIconSource *source,
+                                                          GtkIconSize          size);
 
 G_DEFINE_TYPE (GtkThemingEngine, gtk_theming_engine, G_TYPE_OBJECT)
 
@@ -220,6 +223,7 @@ gtk_theming_engine_class_init (GtkThemingEngineClass *klass)
   klass->render_extension = gtk_theming_engine_render_extension;
   klass->render_handle = gtk_theming_engine_render_handle;
   klass->render_activity = gtk_theming_engine_render_activity;
+  klass->render_icon_pixbuf = gtk_theming_engine_render_icon_pixbuf;
 
   /**
    * GtkThemingEngine:name:
@@ -2807,3 +2811,91 @@ gtk_theming_engine_render_activity (GtkThemingEngine *engine,
       gtk_theming_engine_render_frame (engine, cr, x, y, width, height);
     }
 }
+
+static GdkPixbuf *
+scale_or_ref (GdkPixbuf *src,
+              gint       width,
+              gint       height)
+{
+  if (width == gdk_pixbuf_get_width (src) &&
+      height == gdk_pixbuf_get_height (src))
+    return g_object_ref (src);
+  else
+    return gdk_pixbuf_scale_simple (src,
+                                    width, height,
+                                    GDK_INTERP_BILINEAR);
+}
+
+static gboolean
+lookup_icon_size (GtkThemingEngine *engine,
+		  GtkIconSize       size,
+		  gint             *width,
+		  gint             *height)
+{
+  GdkScreen *screen;
+  GtkSettings *settings;
+
+  screen = gtk_theming_engine_get_screen (engine);
+  settings = gtk_settings_get_for_screen (screen);
+
+  return gtk_icon_size_lookup_for_settings (settings, size, width, height);
+}
+
+static GdkPixbuf *
+gtk_theming_engine_render_icon_pixbuf (GtkThemingEngine    *engine,
+                                       const GtkIconSource *source,
+                                       GtkIconSize          size)
+{
+  GdkPixbuf *scaled;
+  GdkPixbuf *stated;
+  GdkPixbuf *base_pixbuf;
+  GtkStateFlags state;
+  gint width = 1;
+  gint height = 1;
+
+  base_pixbuf = gtk_icon_source_get_pixbuf (source);
+  state = gtk_theming_engine_get_state (engine);
+
+  g_return_val_if_fail (base_pixbuf != NULL, NULL);
+
+  if (size != (GtkIconSize) -1 &&
+      !lookup_icon_size (engine, size, &width, &height))
+    {
+      g_warning (G_STRLOC ": invalid icon size '%d'", size);
+      return NULL;
+    }
+
+  /* If the size was wildcarded, and we're allowed to scale, then scale; otherwise,
+   * leave it alone.
+   */
+  if (size != (GtkIconSize) -1 &&
+      gtk_icon_source_get_size_wildcarded (source))
+    scaled = scale_or_ref (base_pixbuf, width, height);
+  else
+    scaled = g_object_ref (base_pixbuf);
+
+  /* If the state was wildcarded, then generate a state. */
+  if (gtk_icon_source_get_state_wildcarded (source))
+    {
+      if (state & GTK_STATE_FLAG_INSENSITIVE)
+        {
+          stated = gdk_pixbuf_copy (scaled);
+          gdk_pixbuf_saturate_and_pixelate (scaled, stated,
+                                            0.8, TRUE);
+          g_object_unref (scaled);
+        }
+      else if (state & GTK_STATE_FLAG_PRELIGHT)
+        {
+          stated = gdk_pixbuf_copy (scaled);
+          gdk_pixbuf_saturate_and_pixelate (scaled, stated,
+                                            1.2, FALSE);
+          g_object_unref (scaled);
+        }
+      else
+        stated = scaled;
+    }
+  else
+    stated = scaled;
+
+  return stated;
+}