st/viewport: Include padding in paint volume origin calculation

In the presence of adjustments, the paint volume had its size adjusted
for the padding of the viewport, but not its origin. This was leading to
scrollable viewports with a padding having their paint volumes shifted
too far to the left causing some artifacts on the right when scrolling.

One place where this could be observed was the window list in looking
glass.

This now correctly adjusts the origin, simplifies the code and moves it
into the only condition where the adjustment is needed.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/4146>

diff --git a/src/st/st-viewport.c b/src/st/st-viewport.c
index 259429546a957e8acd2e95c7a9dabebf645cb1ff..d26f5f1758ab365074f1fe3eef9b905539105044 100644 (file)
--- a/src/st/st-viewport.c
+++ b/src/st/st-viewport.c
@@ -534,34 +534,28 @@ st_viewport_get_paint_volume (ClutterActor       *actor,
   StThemeNode *theme_node = st_widget_get_theme_node (ST_WIDGET (actor));
   ClutterActorBox allocation_box;
   ClutterActorBox content_box;
+  graphene_point3d_t origin = { 0 };
   int x, y;
+  double width, height;
 
   /* Setting the paint volume does not make sense when we don't have any allocation */
   if (!clutter_actor_has_allocation (actor))
     return FALSE;
 
-  if (!priv->clip_to_view)
+  if (!priv->clip_to_view || !(priv->hadjustment || priv->vadjustment))
     return CLUTTER_ACTOR_CLASS (st_viewport_parent_class)->get_paint_volume (actor, volume);
 
   /* When have an adjustment we are clipped to the content box, so base
    * our paint volume on that. */
-  if (priv->hadjustment || priv->vadjustment)
-    {
-      double width, height;
 
-      clutter_actor_get_allocation_box (actor, &allocation_box);
-      st_theme_node_get_content_box (theme_node, &allocation_box, &content_box);
+  clutter_actor_get_allocation_box (actor, &allocation_box);
+  st_theme_node_get_content_box (theme_node, &allocation_box, &content_box);
 
-      width = content_box.x2 - content_box.x1;
-      height = content_box.y2 - content_box.y1;
+  width = content_box.x2 - content_box.x1;
+  height = content_box.y2 - content_box.y1;
 
-      clutter_paint_volume_set_width (volume, width);
-      clutter_paint_volume_set_height (volume, height);
-    }
-  else if (!CLUTTER_ACTOR_CLASS (st_viewport_parent_class)->get_paint_volume (actor, volume))
-    {
-      return FALSE;
-    }
+  clutter_paint_volume_set_width (volume, width);
+  clutter_paint_volume_set_height (volume, height);
 
   /* When scrolled, st_viewport_apply_transform() includes the scroll offset
    * and affects paint volumes. This is right for our children, but our paint volume
@@ -569,15 +563,10 @@ st_viewport_get_paint_volume (ClutterActor       *actor,
    * to reverse-compensate here, the same as we do when painting.
    */
   get_border_paint_offsets (viewport, &x, &y);
-  if (x != 0 || y != 0)
-    {
-      graphene_point3d_t origin;
+  origin.x = content_box.x1 + x;
+  origin.y = content_box.y1 + y;
 
-      clutter_paint_volume_get_origin (volume, &origin);
-      origin.x += x;
-      origin.y += y;
-      clutter_paint_volume_set_origin (volume, &origin);
-    }
+  clutter_paint_volume_set_origin (volume, &origin);
 
   return TRUE;
 }