[gnome-shell] st: Report correct paint volumes during transitions

[Florian Müllner <fmuellner src gnome org>]

commit 289d577bc15b6406930adcfd2ab970c0d6330796
Author: Florian Müllner <fmuellner gnome org>
Date:   Thu Jan 20 21:15:05 2011 +0100

    st: Report correct paint volumes during transitions
    
    StWidget reports a paint volume large enough to paint the current
    theme node. As CSS transitions also paint the previous theme node,
    the reported paint volume may be incorrect, resulting in screen
    artifacts when painting outside the reported volume.
    
    Add st_theme_node_transition_get_paint_box() to calculate an allocation
    large enough to paint both theme nodes, and use it to report the correct
    paint volume during transitions.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=640085

 src/st/st-theme-node-transition.c |   28 ++++++++++++++++++++--------
 src/st/st-theme-node-transition.h |    4 ++++
 src/st/st-widget.c                |   10 +++++++++-
 3 files changed, 33 insertions(+), 9 deletions(-)
---
diff --git a/src/st/st-theme-node-transition.c b/src/st/st-theme-node-transition.c
index ea1ba1c..3da45ae 100644
--- a/src/st/st-theme-node-transition.c
+++ b/src/st/st-theme-node-transition.c
@@ -183,6 +183,22 @@ static void
 calculate_offscreen_box (StThemeNodeTransition *transition,
                          const ClutterActorBox *allocation)
 {
+  ClutterActorBox paint_box;
+
+  st_theme_node_transition_get_paint_box (transition,
+                                          allocation,
+                                          &paint_box);
+  transition->priv->offscreen_box.x1 = paint_box.x1 - allocation->x1;
+  transition->priv->offscreen_box.y1 = paint_box.y1 - allocation->y1;
+  transition->priv->offscreen_box.x2 = paint_box.x2 - allocation->x1;
+  transition->priv->offscreen_box.y2 = paint_box.y2 - allocation->y1;
+}
+
+void
+st_theme_node_transition_get_paint_box (StThemeNodeTransition *transition,
+                                        const ClutterActorBox *allocation,
+                                        ClutterActorBox       *paint_box)
+{
   StThemeNodeTransitionPrivate *priv = transition->priv;
   ClutterActorBox old_node_box, new_node_box;
 
@@ -194,14 +210,10 @@ calculate_offscreen_box (StThemeNodeTransition *transition,
                                allocation,
                                &new_node_box);
 
-  priv->offscreen_box.x1 = MIN (old_node_box.x1, new_node_box.x1)
-                           - allocation->x1;
-  priv->offscreen_box.y1 = MIN (old_node_box.y1, new_node_box.y1)
-                           - allocation->y1;
-  priv->offscreen_box.x2 = MAX (old_node_box.x2, new_node_box.x2)
-                           - allocation->x1;
-  priv->offscreen_box.y2 = MAX (old_node_box.y2, new_node_box.y2)
-                           - allocation->y1;
+  paint_box->x1 = MIN (old_node_box.x1, new_node_box.x1);
+  paint_box->y1 = MIN (old_node_box.y1, new_node_box.y1);
+  paint_box->x2 = MAX (old_node_box.x2, new_node_box.x2);
+  paint_box->y2 = MAX (old_node_box.y2, new_node_box.y2);
 }
 
 static gboolean
diff --git a/src/st/st-theme-node-transition.h b/src/st/st-theme-node-transition.h
index 3bcef9b..d6fd935 100644
--- a/src/st/st-theme-node-transition.h
+++ b/src/st/st-theme-node-transition.h
@@ -65,6 +65,10 @@ void  st_theme_node_transition_paint    (StThemeNodeTransition *transition,
                                          ClutterActorBox       *allocation,
                                          guint8                 paint_opacity);
 
+void  st_theme_node_transition_get_paint_box (StThemeNodeTransition *transition,
+                                              const ClutterActorBox *allocation,
+                                              ClutterActorBox       *paint_box);
+
 G_END_DECLS
 
 #endif
diff --git a/src/st/st-widget.c b/src/st/st-widget.c
index 8ebe1dd..71c1518 100644
--- a/src/st/st-widget.c
+++ b/src/st/st-widget.c
@@ -686,15 +686,23 @@ st_widget_get_paint_volume (ClutterActor *self, ClutterPaintVolume *volume)
 {
   ClutterActorBox paint_box, alloc_box;
   StThemeNode *theme_node;
+  StWidgetPrivate *priv;
   ClutterVertex origin;
 
   /* Setting the paint volume does not make sense when we don't have any allocation */
   if (!clutter_actor_has_allocation (self))
     return FALSE;
 
+  priv = ST_WIDGET(self)->priv;
+
   theme_node = st_widget_get_theme_node (ST_WIDGET(self));
   clutter_actor_get_allocation_box (self, &alloc_box);
-  st_theme_node_get_paint_box (theme_node, &alloc_box, &paint_box);
+
+  if (priv->transition_animation)
+    st_theme_node_transition_get_paint_box (priv->transition_animation,
+                                            &alloc_box, &paint_box);
+  else
+    st_theme_node_get_paint_box (theme_node, &alloc_box, &paint_box);
 
   origin.x = paint_box.x1 - alloc_box.x1;
   origin.y = paint_box.y1 - alloc_box.y1;