GtkIconTheme: Add helpers to load to cairo_surface_t

Right now this just uses the pixbuf load code and converts
it to a surface. In the future we could cache the pattern
to allow reusing the surface.

gtk/gtkicontheme.c

@@ -2080,6 +2080,69 @@ gtk_icon_theme_load_icon_for_scale (GtkIconTheme        *icon_theme,
   return pixbuf;
 }
 
+/**
+ * gtk_icon_theme_load_surface:
+ * @icon_theme: a #GtkIconTheme
+ * @icon_name: the name of the icon to lookup
+ * @size: the desired icon size. The resulting icon may not be
+ *     exactly this size; see gtk_icon_info_load_icon().
+ * @scale: desired scale
+ * @for_window: (allow-none): #GdkWindow to optimize drawing for, or %NULL
+ * @flags: flags modifying the behavior of the icon lookup
+ * @error: (allow-none): Location to store error information on failure,
+ *     or %NULL.
+ *
+ * Looks up an icon in an icon theme for a particular window scale,
+ * scales it to the given size and renders it into a cairo surface. This is a
+ * convenience function; if more details about the icon are needed,
+ * use gtk_icon_theme_lookup_icon() followed by
+ * gtk_icon_info_load_surface().
+ *
+ * Note that you probably want to listen for icon theme changes and
+ * update the icon. This is usually done by connecting to the
+ * GtkWidget::style-set signal.
+ *
+ * Return value: (transfer full): the rendered icon; this may be a
+ *     newly created icon or a new reference to an internal icon, so
+ *     you must not modify the icon. Use cairo_surface_destroy() to release
+ *     your reference to the icon. %NULL if the icon isn't found.
+ *
+ * Since: 3.10
+ **/
+cairo_surface_t *
+gtk_icon_theme_load_surface (GtkIconTheme        *icon_theme,
+			     const gchar         *icon_name,
+			     gint                 size,
+			     gint                 scale,
+			     GdkWindow           *for_window,
+			     GtkIconLookupFlags   flags,
+			     GError             **error)
+{
+  GtkIconInfo *icon_info;
+  cairo_surface_t *surface = NULL;
+  
+  g_return_val_if_fail (GTK_IS_ICON_THEME (icon_theme), NULL);
+  g_return_val_if_fail (icon_name != NULL, NULL);
+  g_return_val_if_fail ((flags & GTK_ICON_LOOKUP_NO_SVG) == 0 ||
+			(flags & GTK_ICON_LOOKUP_FORCE_SVG) == 0, NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+  g_return_val_if_fail (scale >= 1, NULL);
+
+  icon_info = gtk_icon_theme_lookup_icon_for_scale (icon_theme, icon_name, size, scale,
+                                                    flags | GTK_ICON_LOOKUP_USE_BUILTIN);
+  if (!icon_info)
+    {
+      g_set_error (error, GTK_ICON_THEME_ERROR,  GTK_ICON_THEME_NOT_FOUND,
+		   _("Icon '%s' not present in theme"), icon_name);
+      return NULL;
+    }
+
+  surface = gtk_icon_info_load_surface (icon_info, for_window, error);
+  g_object_unref (icon_info);
+
+  return surface;
+}
+
 /**
  * gtk_icon_theme_has_icon:
  * @icon_theme: a #GtkIconTheme
@@ -3802,6 +3865,54 @@ gtk_icon_info_load_icon (GtkIconInfo *icon_info,
   return icon_info->proxy_pixbuf;
 }
 
+/**
+ * gtk_icon_info_load_surface:
+ * @icon_info: a #GtkIconInfo structure from gtk_icon_theme_lookup_icon()
+ * @for_window: (allow-none): #GdkWindow to optimize drawing for, or %NULL
+ * @error: (allow-none): location to store error information on failure,
+ *     or %NULL.
+ *
+ * Renders an icon previously looked up in an icon theme using
+ * gtk_icon_theme_lookup_icon(); the size will be based on the size
+ * passed to gtk_icon_theme_lookup_icon(). Note that the resulting
+ * surface may not be exactly this size; an icon theme may have icons
+ * that differ slightly from their nominal sizes, and in addition GTK+
+ * will avoid scaling icons that it considers sufficiently close to the
+ * requested size or for which the source image would have to be scaled
+ * up too far. (This maintains sharpness.). This behaviour can be changed
+ * by passing the %GTK_ICON_LOOKUP_FORCE_SIZE flag when obtaining
+ * the #GtkIconInfo. If this flag has been specified, the pixbuf
+ * returned by this function will be scaled to the exact size.
+ *
+ * Return value: (transfer full): the rendered icon; this may be a newly
+ *     created icon or a new reference to an internal icon, so you must
+ *     not modify the icon. Use cairo_surface_destroy() to release your reference
+ *     to the icon.
+ *
+ * Since: 3.10
+ **/
+cairo_surface_t *
+gtk_icon_info_load_surface (GtkIconInfo *icon_info,
+			    GdkWindow *for_window,
+			    GError     **error)
+{
+  GdkPixbuf *pixbuf;
+  cairo_surface_t *surface;
+
+  g_return_val_if_fail (icon_info != NULL, NULL);
+  g_return_val_if_fail (error == NULL || *error == NULL, NULL);
+
+  pixbuf = gtk_icon_info_load_icon (icon_info, error);
+
+  if (pixbuf == NULL)
+    return NULL;
+
+  surface = gdk_cairo_surface_create_from_pixbuf (pixbuf, icon_info->desired_scale, for_window);
+  g_object_unref (pixbuf);
+
+  return surface;
+}
+
 static void
 load_icon_thread  (GTask           *task,
 		   gpointer         source_object,

gtk/gtkicontheme.h

@@ -210,6 +210,14 @@ GdkPixbuf *   gtk_icon_theme_load_icon_for_scale   (GtkIconTheme
                                                     gint                         scale,
                                                     GtkIconLookupFlags           flags,
                                                     GError                     **error);
+GDK_AVAILABLE_IN_3_10
+cairo_surface_t * gtk_icon_theme_load_surface      (GtkIconTheme        *icon_theme,
+						    const gchar         *icon_name,
+						    gint                 size,
+						    gint                 scale,
+						    GdkWindow           *for_window,
+						    GtkIconLookupFlags   flags,
+						    GError             **error);
 
 GDK_AVAILABLE_IN_ALL
 GtkIconInfo * gtk_icon_theme_lookup_by_gicon       (GtkIconTheme                *icon_theme,
@@ -261,6 +269,10 @@ GdkPixbuf *           gtk_icon_info_get_builtin_pixbuf (GtkIconInfo   *icon_info
 GDK_AVAILABLE_IN_ALL
 GdkPixbuf *           gtk_icon_info_load_icon          (GtkIconInfo   *icon_info,
 							GError       **error);
+GDK_AVAILABLE_IN_3_10
+cairo_surface_t *     gtk_icon_info_load_surface       (GtkIconInfo   *icon_info,
+							GdkWindow     *for_window,
+							GError       **error);
 GDK_AVAILABLE_IN_3_8
 void                  gtk_icon_info_load_icon_async   (GtkIconInfo          *icon_info,
 						       GCancellable         *cancellable,