[gnome-shell] st-theme-node: let paint states take weak ref on theme nodes

[Lionel Landwerlin <llandwerlin src gnome org>]

commit a18fb27d0f41b4c7b8731426d3528dd6bea4bd42
Author: Lionel Landwerlin <llandwerlin gmail com>
Date:   Wed Jul 10 10:22:07 2013 +0100

    st-theme-node: let paint states take weak ref on theme nodes
    
    When the St theme is changed, the StThemeContext unrefs all the theme
    nodes cached in it's internal hash table, then emits a signal to
    notify all theme nodes that the current theme has changed.
    
    The problem is that the first StWidget to catch a theme changed signal
    will trigger a "style-changed" signal catched by its children first.
    So the theme changed signal can't be processed properly to cleanup
    StThemeNodePaintState before recomputing the theme.
    
    This patch adds a weak ref to the StThemeNode in the
    StThemeNodePaintState to ensure paint states are properly cleaned up
    when the associated StThemeNode is freed.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=703859

 src/st/st-theme-node-drawing.c |   41 +++++++++++++++++++++++++++++++++++----
 src/st/st-theme-node.h         |    2 +
 2 files changed, 38 insertions(+), 5 deletions(-)
---
diff --git a/src/st/st-theme-node-drawing.c b/src/st/st-theme-node-drawing.c
index 0b76f6b..e8ba869 100644
--- a/src/st/st-theme-node-drawing.c
+++ b/src/st/st-theme-node-drawing.c
@@ -1391,7 +1391,7 @@ st_theme_node_render_resources (StThemeNodePaintState *state,
    */
   st_theme_node_paint_state_free (state);
 
-  state->node = node;
+  st_theme_node_paint_state_set_node (state, node);
   state->alloc_width = width;
   state->alloc_height = height;
 
@@ -1526,7 +1526,7 @@ st_theme_node_update_resources (StThemeNodePaintState *state,
         }
     }
 
-  state->node = node;
+  st_theme_node_paint_state_set_node (state, node);
   state->alloc_width = width;
   state->alloc_height = height;
 
@@ -2523,8 +2523,9 @@ st_theme_node_paint (StThemeNode           *node,
     }
 }
 
-void
-st_theme_node_paint_state_free (StThemeNodePaintState *state)
+static void
+st_theme_node_paint_state_node_free_internal (StThemeNodePaintState *state,
+                                              gboolean               unref_node)
 {
   int corner_id;
 
@@ -2539,9 +2540,39 @@ st_theme_node_paint_state_free (StThemeNodePaintState *state)
     if (state->corner_material[corner_id] != COGL_INVALID_HANDLE)
       cogl_handle_unref (state->corner_material[corner_id]);
 
+  if (unref_node)
+    st_theme_node_paint_state_set_node (state, NULL);
+
   st_theme_node_paint_state_init (state);
 }
 
+static void
+st_theme_node_paint_state_node_freed (StThemeNodePaintState *state)
+{
+  st_theme_node_paint_state_node_free_internal (state, FALSE);
+}
+
+void
+st_theme_node_paint_state_set_node (StThemeNodePaintState *state, StThemeNode *node)
+{
+  if (state->node)
+    g_object_weak_unref (G_OBJECT (state->node),
+                         (GWeakNotify) st_theme_node_paint_state_node_freed,
+                         state);
+
+  state->node = node;
+  if (state->node)
+    g_object_weak_ref (G_OBJECT (state->node),
+                       (GWeakNotify) st_theme_node_paint_state_node_freed,
+                       state);
+}
+
+void
+st_theme_node_paint_state_free (StThemeNodePaintState *state)
+{
+  st_theme_node_paint_state_node_free_internal (state, TRUE);
+}
+
 void
 st_theme_node_paint_state_init (StThemeNodePaintState *state)
 {
@@ -2567,7 +2598,7 @@ st_theme_node_paint_state_copy (StThemeNodePaintState *state,
 
   st_theme_node_paint_state_free (state);
 
-  state->node = other->node;
+  st_theme_node_paint_state_set_node (state, other->node);
 
   state->alloc_width = other->alloc_width;
   state->alloc_height = other->alloc_height;
diff --git a/src/st/st-theme-node.h b/src/st/st-theme-node.h
index 8f3a378..5fffa63 100644
--- a/src/st/st-theme-node.h
+++ b/src/st/st-theme-node.h
@@ -281,6 +281,8 @@ void st_theme_node_paint_state_free (StThemeNodePaintState *state);
 void st_theme_node_paint_state_copy (StThemeNodePaintState *state,
                                      StThemeNodePaintState *other);
 void st_theme_node_paint_state_invalidate (StThemeNodePaintState *state);
+void st_theme_node_paint_state_set_node (StThemeNodePaintState *state,
+                                         StThemeNode           *node);
 
 G_END_DECLS