[mutter] window-actor/x11: Cache the client area

[Robert Mader <rmader src gnome org>]

commit 7dbb4bc3f5ee0c6f796f2d629137b2aabc52aa7c
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Thu Jan 16 09:06:42 2020 +0100

    window-actor/x11: Cache the client area
    
    With Xwayland, the shape region is recomputed and reapplied even when
    the actor is frozen to prevent the black shadows effect.
    
    However, while recomputing the shape region, the current client size is
    taken into account, rather than the size when the client was frozen,
    which is ahead of the actual client size using the NET_WM_SYNC protocol.
    
    Keep the current client area and to reuse them when the X11 window actor
    is frozen for rebuilding the client mask texture.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/1009

 src/compositor/meta-window-actor-x11.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)
---
diff --git a/src/compositor/meta-window-actor-x11.c b/src/compositor/meta-window-actor-x11.c
index 11816bbeb..81816bae0 100644
--- a/src/compositor/meta-window-actor-x11.c
+++ b/src/compositor/meta-window-actor-x11.c
@@ -99,6 +99,8 @@ struct _MetaWindowActorX11
   gboolean recompute_focused_shadow;
   gboolean recompute_unfocused_shadow;
   gboolean is_frozen;
+
+  cairo_rectangle_int_t client_area;
 };
 
 static MetaCullableInterface *cullable_parent_iface;
@@ -839,7 +841,6 @@ scan_visible_region (guchar         *mask_data,
 
 static void
 build_and_scan_frame_mask (MetaWindowActorX11    *actor_x11,
-                           cairo_rectangle_int_t *client_area,
                            cairo_region_t        *shape_region)
 {
   ClutterBackend *backend = clutter_get_default_backend ();
@@ -892,7 +893,8 @@ build_and_scan_frame_mask (MetaWindowActorX11    *actor_x11,
 
       /* Make sure we don't paint the frame over the client window. */
       frame_paint_region = cairo_region_create_rectangle (&rect);
-      cairo_region_subtract_rectangle (frame_paint_region, client_area);
+      cairo_region_subtract_rectangle (frame_paint_region,
+                                       &actor_x11->client_area);
 
       gdk_cairo_region (cr, frame_paint_region);
       cairo_clip (cr);
@@ -950,14 +952,13 @@ update_shape_region (MetaWindowActorX11 *actor_x11)
   MetaWindow *window =
     meta_window_actor_get_meta_window (META_WINDOW_ACTOR (actor_x11));
   cairo_region_t *region = NULL;
-  cairo_rectangle_int_t client_area;
-
-  meta_window_get_client_area_rect (window, &client_area);
 
   if (window->frame && window->shape_region)
     {
       region = cairo_region_copy (window->shape_region);
-      cairo_region_translate (region, client_area.x, client_area.y);
+      cairo_region_translate (region,
+                              actor_x11->client_area.x,
+                              actor_x11->client_area.y);
     }
   else if (window->shape_region != NULL)
     {
@@ -968,11 +969,11 @@ update_shape_region (MetaWindowActorX11 *actor_x11)
       /* If we don't have a shape on the server, that means that
        * we have an implicit shape of one rectangle covering the
        * entire window. */
-      region = cairo_region_create_rectangle (&client_area);
+      region = cairo_region_create_rectangle (&actor_x11->client_area);
     }
 
   if (window->shape_region || window->frame)
-    build_and_scan_frame_mask (actor_x11, &client_area, region);
+    build_and_scan_frame_mask (actor_x11, region);
 
   g_clear_pointer (&actor_x11->shape_region, cairo_region_destroy);
   actor_x11->shape_region = region;
@@ -1046,10 +1047,6 @@ update_opaque_region (MetaWindowActorX11 *actor_x11)
   is_maybe_transparent = is_actor_maybe_transparent (actor_x11);
   if (is_maybe_transparent && window->opaque_region)
     {
-      cairo_rectangle_int_t client_area;
-
-      meta_window_get_client_area_rect (window, &client_area);
-
       /* The opaque region is defined to be a part of the
        * window which ARGB32 will always paint with opaque
        * pixels. For these regions, we want to avoid painting
@@ -1061,7 +1058,9 @@ update_opaque_region (MetaWindowActorX11 *actor_x11)
        * case, graphical glitches will occur.
        */
       opaque_region = cairo_region_copy (window->opaque_region);
-      cairo_region_translate (opaque_region, client_area.x, client_area.y);
+      cairo_region_translate (opaque_region,
+                              actor_x11->client_area.x,
+                              actor_x11->client_area.y);
       cairo_region_intersect (opaque_region, actor_x11->shape_region);
     }
   else if (is_maybe_transparent)
@@ -1110,16 +1109,15 @@ handle_updates (MetaWindowActorX11 *actor_x11)
 {
   MetaSurfaceActor *surface =
     meta_window_actor_get_surface (META_WINDOW_ACTOR (actor_x11));
+  MetaWindow *window;
 
   if (META_IS_SURFACE_ACTOR_X11 (surface) &&
       meta_surface_actor_x11_is_unredirected (META_SURFACE_ACTOR_X11 (surface)))
     return;
 
+  window = meta_window_actor_get_meta_window (META_WINDOW_ACTOR (actor_x11));
   if (meta_window_actor_is_frozen (META_WINDOW_ACTOR (actor_x11)))
     {
-      MetaWindow *window =
-        meta_window_actor_get_meta_window (META_WINDOW_ACTOR (actor_x11));
-
       /* The window is frozen due to a pending animation: we'll wait until
        * the animation finishes to repair the window.
        *
@@ -1138,6 +1136,7 @@ handle_updates (MetaWindowActorX11 *actor_x11)
   if (!meta_surface_actor_is_visible (surface))
     return;
 
+  meta_window_get_client_area_rect (window, &actor_x11->client_area);
   check_needs_reshape (actor_x11);
   check_needs_shadow (actor_x11);
 }