stage: implicitly clip to stage window bounds

This implicitly intersects any clip for redrawing with the stage window
bounds. Without this we were sometimes trying to set huge off screen
scissors leading to undefined clipping results.

Reviewed-by: Emmanuele Bassi <ebassi@linux.intel.com>

diff --git a/clutter/clutter-stage.c b/clutter/clutter-stage.c
index 0abe9e9..e8471bb 100644 (file)
--- a/clutter/clutter-stage.c
+++ b/clutter/clutter-stage.c
@@ -529,24 +529,23 @@ _clutter_stage_do_paint (ClutterStage *stage, const ClutterGeometry *clip)
 {
   ClutterStagePrivate *priv = stage->priv;
   float clip_poly[8];
+  ClutterGeometry geom;
+
+  _clutter_stage_window_get_geometry (priv->impl, &geom);
 
   if (clip)
     {
-      clip_poly[0] = clip->x;
-      clip_poly[1] = clip->y;
-      clip_poly[2] = clip->x + clip->width;
-      clip_poly[3] = clip->y;
-      clip_poly[4] = clip->x + clip->width;
-      clip_poly[5] = clip->y + clip->height;
-      clip_poly[6] = clip->x;
-      clip_poly[7] = clip->y + clip->height;
+      clip_poly[0] = MAX (clip->x, 0);
+      clip_poly[1] = MAX (clip->y, 0);
+      clip_poly[2] = MIN (clip->x + clip->width, geom.width);
+      clip_poly[3] = clip_poly[1];
+      clip_poly[4] = clip_poly[2];
+      clip_poly[5] = MIN (clip->y + clip->height, geom.height);
+      clip_poly[6] = clip_poly[0];
+      clip_poly[7] = clip_poly[5];
     }
   else
     {
-      ClutterGeometry geom;
-
-      _clutter_stage_window_get_geometry (priv->impl, &geom);
-
       clip_poly[0] = 0;
       clip_poly[1] = 0;
       clip_poly[2] = geom.width;
@@ -1118,6 +1117,8 @@ clutter_stage_real_queue_redraw (ClutterActor *actor,
   ClutterGeometry stage_clip;
   ClutterPaintVolume *redraw_clip;
   ClutterActorBox bounding_box;
+  ClutterActorBox intersection_box;
+  ClutterGeometry geom;
 
   if (CLUTTER_ACTOR_IN_DESTRUCTION (actor))
     return;
@@ -1151,12 +1152,24 @@ clutter_stage_real_queue_redraw (ClutterActor *actor,
                                              stage,
                                              &bounding_box);
 
+  _clutter_stage_window_get_geometry (stage_window, &geom);
+
+  intersection_box.x1 = MAX (bounding_box.x1, 0);
+  intersection_box.y1 = MAX (bounding_box.y1, 0);
+  intersection_box.x2 = MIN (bounding_box.x2, geom.width);
+  intersection_box.y2 = MIN (bounding_box.y2, geom.height);
+
+  /* There is no need to track degenerate/empty redraw clips */
+  if (intersection_box.x2 <= intersection_box.x1 ||
+      intersection_box.y2 <= intersection_box.y1)
+    return;
+
   /* when converting to integer coordinates make sure we round the edges of the
    * clip rectangle outwards... */
-  stage_clip.x = bounding_box.x1;
-  stage_clip.y = bounding_box.y1;
-  stage_clip.width = bounding_box.x2 - stage_clip.x;
-  stage_clip.height = bounding_box.y2 - stage_clip.y;
+  stage_clip.x = intersection_box.x1;
+  stage_clip.y = intersection_box.y1;
+  stage_clip.width = intersection_box.x2 - stage_clip.x;
+  stage_clip.height = intersection_box.y2 - stage_clip.y;
 
   _clutter_stage_window_add_redraw_clip (stage_window, &stage_clip);
 }