GtkHeaderBar: try harder to find the best window icon

GtkWindow has 4 (!) APIs for setting window icons, and we
have to try them all in the right order to find the right
icon. This commit makes it so, and keeps the icon list
manipulation inside gtkwindow.c by adding a private API
for getting a single icon at the right size.

https://bugzilla.gnome.org/show_bug.cgi?id=722515

3 files changed, 76 insertions, 40 deletions

diff --git a/gtk/gtkheaderbar.c b/gtk/gtkheaderbar.c
index 3b9923eea2..36c7e70081 100644
--- a/gtk/gtkheaderbar.c
+++ b/gtk/gtkheaderbar.c
@@ -218,54 +218,20 @@ _gtk_header_bar_update_window_icon (GtkHeaderBar *bar,
                                     GtkWindow    *window)
 {
   GtkHeaderBarPrivate *priv = gtk_header_bar_get_instance_private (bar);
-  gint size;
-  GList *list;
-  const gchar *name;
-  GdkPixbuf *best = NULL;
+  GdkPixbuf *pixbuf;
 
   if (priv->titlebar_icon == NULL)
     return FALSE;
 
   if (GTK_IS_BUTTON (gtk_widget_get_parent (priv->titlebar_icon)))
-    size = 16;
+    pixbuf = gtk_window_get_icon_for_size (window, 16);
   else
-    size = 20;
+    pixbuf = gtk_window_get_icon_for_size (window, 20);
 
-  list = gtk_window_get_icon_list (window);
-
-  if (list != NULL)
-    {
-      GdkPixbuf *pixbuf;
-      GList *l;
-
-      best = NULL;
-      for (l = list; l; l = l->next)
-        {
-          pixbuf = list->data;
-          if (gdk_pixbuf_get_width (pixbuf) <= size)
-            {
-              best = g_object_ref (pixbuf);
-              break;
-            }
-        }
-
-      if (best == NULL)
-        best = gdk_pixbuf_scale_simple (GDK_PIXBUF (list->data), size, size, GDK_INTERP_BILINEAR);
-
-      g_list_free (list);
-    }
-  else
-    {
-      name = gtk_window_get_icon_name (window);
-      if (name != NULL)
-        best = gtk_icon_theme_load_icon (gtk_icon_theme_get_default (),
-                                         name, size, GTK_ICON_LOOKUP_FORCE_SIZE, NULL);
-    }
-
-  if (best)
+  if (pixbuf)
     {
-      gtk_image_set_from_pixbuf (GTK_IMAGE (priv->titlebar_icon), best);
-      g_object_unref (best);
+      gtk_image_set_from_pixbuf (GTK_IMAGE (priv->titlebar_icon), pixbuf);
+      g_object_unref (pixbuf);
       gtk_widget_show (priv->titlebar_icon);
 
       return TRUE;
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index f42f9f76a9..5e2cc05aee 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -4019,6 +4019,73 @@ gtk_window_realize_icon (GtkWindow *window)
     }
 }
 
+static GdkPixbuf *
+icon_from_list (GList *list,
+                gint   size)
+{
+  GdkPixbuf *best;
+  GdkPixbuf *pixbuf;
+  GList *l;
+
+  best = NULL;
+  for (l = list; l; l = l->next)
+    {
+      pixbuf = list->data;
+      if (gdk_pixbuf_get_width (pixbuf) <= size)
+        {
+          best = g_object_ref (pixbuf);
+          break;
+        }
+    }
+
+  if (best == NULL)
+    best = gdk_pixbuf_scale_simple (GDK_PIXBUF (list->data), size, size, GDK_INTERP_BILINEAR);
+
+  return best;
+}
+
+static GdkPixbuf *
+icon_from_name (const gchar *name,
+                gint         size)
+{
+  return gtk_icon_theme_load_icon (gtk_icon_theme_get_default (),
+                                   name, size,
+                                   GTK_ICON_LOOKUP_FORCE_SIZE, NULL);
+}
+
+GdkPixbuf *
+gtk_window_get_icon_for_size (GtkWindow *window,
+                              gint       size)
+{
+  GtkWindowPrivate *priv = window->priv;
+  GtkWindowIconInfo *info;
+  const gchar *name;
+
+  info = ensure_icon_info (window);
+
+  if (info->icon_list != NULL)
+    return icon_from_list (info->icon_list, size);
+
+  name = gtk_window_get_icon_name (window);
+  if (name != NULL)
+    return icon_from_name (name, size);
+
+  if (priv->transient_parent != NULL)
+    {
+      info = ensure_icon_info (priv->transient_parent);
+      if (info->icon_list)
+        return icon_from_list (info->icon_list, size);
+    }
+
+  if (default_icon_list != NULL)
+    return icon_from_list (default_icon_list, size);
+
+  if (default_icon_name != NULL)
+    return icon_from_name (default_icon_name, size);
+
+  return NULL;
+}
+
 static void
 gtk_window_unrealize_icon (GtkWindow *window)
 {
diff --git a/gtk/gtkwindowprivate.h b/gtk/gtkwindowprivate.h
index 9f9bce6bd0..704026d001 100644
--- a/gtk/gtkwindowprivate.h
+++ b/gtk/gtkwindowprivate.h
@@ -107,6 +107,9 @@ void    _gtk_window_get_popover_position (GtkWindow                   *window,
                                           GtkPositionType             *pos,
                                           cairo_rectangle_int_t       *rect);
 
+GdkPixbuf *gtk_window_get_icon_for_size (GtkWindow *window,
+                                         gint       size);
+
 G_END_DECLS
 
 #endif /* __GTK_WINDOW_PRIVATE_H__ */