[gtk+/wip/simple-draw4] Add gdk_window_get_children_with_user_data

[Alexander Larsson <alexl src gnome org>]

commit 97ad2d7897f222598c3d36d4cf0e707a320a959d
Author: Alexander Larsson <alexl redhat com>
Date:   Fri May 3 10:39:24 2013 +0200

    Add gdk_window_get_children_with_user_data
    
    This function returns all the children that has a specific user_data set.
    This is used a lot in the new GtkWidget drawing code and doing
    it this way is faster than getting every child and calling get_user_data
    on each (which was a non-neglible part of the profiles). Additionally it
    also allows use to use some kind of hashtable to make this operation even
    faster if needed in the future.

 gdk/gdkwindow.c |   41 +++++++++++++++++++++++++++++++++++++++++
 gdk/gdkwindow.h |    3 +++
 2 files changed, 44 insertions(+), 0 deletions(-)
---
diff --git a/gdk/gdkwindow.c b/gdk/gdkwindow.c
index 39ccda0..7a9b0c3 100644
--- a/gdk/gdkwindow.c
+++ b/gdk/gdkwindow.c
@@ -2399,6 +2399,47 @@ gdk_window_peek_children (GdkWindow *window)
   return window->children;
 }
 
+
+/**
+ * gdk_window_get_children_with_user_data:
+ * @window: a #GdkWindow
+ *
+ * Gets the list of children of @window known to GDK with a particular
+ * user_data set on it.
+ *
+ * The returned list must be freed, but the elements in the
+ * list need not be.
+ *
+ * The list is returned in (relative) stacking order, i.e. the
+ * lowest window is first.
+ *
+ * Return value: (transfer container) (element-type GdkWindow):
+ *     list of child windows inside @window
+ **/
+GList *
+gdk_window_get_children_with_user_data (GdkWindow *window, gpointer user_data)
+{
+  GdkWindow *child;
+  GList *res, *l;
+
+  g_return_val_if_fail (GDK_IS_WINDOW (window), NULL);
+
+  if (GDK_WINDOW_DESTROYED (window))
+    return NULL;
+
+  res = NULL;
+  for (l = window->children; l != NULL; l = l->next)
+    {
+      child = l->data;
+
+      if (child->user_data == user_data)
+       res = g_list_prepend (res, child);
+    }
+
+  return res;
+}
+
+
 /**
  * gdk_window_add_filter: (skip)
  * @window: (allow-none): a #GdkWindow
diff --git a/gdk/gdkwindow.h b/gdk/gdkwindow.h
index 6ee09c4..2d4fa7a 100644
--- a/gdk/gdkwindow.h
+++ b/gdk/gdkwindow.h
@@ -767,6 +767,9 @@ GdkWindow *   gdk_window_get_effective_toplevel (GdkWindow *window);
 
 GList *              gdk_window_get_children    (GdkWindow       *window);
 GList *       gdk_window_peek_children   (GdkWindow       *window);
+GList *       gdk_window_get_children_with_user_data (GdkWindow *window,
+                                                     gpointer user_data);
+
 GdkEventMask  gdk_window_get_events     (GdkWindow       *window);
 void         gdk_window_set_events      (GdkWindow       *window,
                                          GdkEventMask     event_mask);