[mutter] clutter/actor: Inherit cloned painting when calculating resource scale

[Jonas Ådahl <jadahl src gnome org>]

commit 32c99513c8b39f09d0769ec0873f836e586c93a8
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Mar 24 18:32:18 2020 +0100

    clutter/actor: Inherit cloned painting when calculating resource scale
    
    When calculating the resource scale of a clone source, we might end up
    in situations where we fail to do so, even though we're in a paint. A
    real world example when this may happen if this happens:
    
     * A client creates a toplevel window
     * A client creates a modal dialog for said toplevel window
     * Said client commits a buffer to the modal before the toplevel
    
    If GNOME Shell is in overview mode, the window group is hidden, and the
    toplevel window actor is hidden. When the clone tries to paint, it fails
    to calculate the resource scale, as the parent of the parent (window
    group) is not currently mapped. It would have succeeded if only the
    clone source was unmapped, as it deals with the unmapped actor painting
    by setting intermediate state while painting, but this does not work
    when the *parent* of the source is unmapped as well.
    
    Fix this by inheriting the unmapped clone paint even when calculating
    the resource scale.
    
    This also adds a test case that mimics the sequence of events otherwise
    triggered by a client. We can't add a Wayland client to test this, where
    we actually crash is in the offscreen redirect effect used by the window
    dimming feature in GNOME Shell.
    
    Fixes: https://gitlab.gnome.org/GNOME/mutter/-/issues/808
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1147

 clutter/clutter/clutter-actor.c         | 38 ++++++++++++++++--
 src/tests/clutter/conform/actor-clone.c | 68 +++++++++++++++++++++++++++++++++
 src/tests/clutter/conform/meson.build   |  1 +
 3 files changed, 104 insertions(+), 3 deletions(-)
---
diff --git a/clutter/clutter/clutter-actor.c b/clutter/clutter/clutter-actor.c
index d35dffb02..2841be091 100644
--- a/clutter/clutter/clutter-actor.c
+++ b/clutter/clutter/clutter-actor.c
@@ -17715,10 +17715,42 @@ _clutter_actor_compute_resource_scale (ClutterActor *self,
                                                    resource_scale))
     {
       if (priv->parent)
-        return _clutter_actor_compute_resource_scale (priv->parent,
-                                                      resource_scale);
+        {
+          gboolean in_clone_paint;
+          gboolean was_parent_in_clone_paint;
+          gboolean was_parent_unmapped;
+          gboolean was_parent_paint_unmapped;
+          gboolean ret;
+
+          in_clone_paint = clutter_actor_is_in_clone_paint (self);
+          was_parent_unmapped = !clutter_actor_is_mapped (priv->parent);
+          was_parent_in_clone_paint =
+            clutter_actor_is_in_clone_paint (priv->parent);
+          was_parent_paint_unmapped = priv->parent->priv->enable_paint_unmapped;
+
+          if (in_clone_paint && was_parent_unmapped)
+            {
+              _clutter_actor_set_in_clone_paint (priv->parent, TRUE);
+              _clutter_actor_set_enable_paint_unmapped (priv->parent, TRUE);
+            }
+
+          ret = _clutter_actor_compute_resource_scale (priv->parent,
+                                                       resource_scale);
+
+          if (in_clone_paint && was_parent_unmapped)
+            {
+              _clutter_actor_set_in_clone_paint (priv->parent,
+                                                 was_parent_in_clone_paint);
+              _clutter_actor_set_enable_paint_unmapped (priv->parent,
+                                                        was_parent_paint_unmapped);
+            }
+
+          return ret;
+        }
       else
-        return FALSE;
+        {
+          return FALSE;
+        }
     }
 
   return TRUE;
diff --git a/src/tests/clutter/conform/actor-clone.c b/src/tests/clutter/conform/actor-clone.c
new file mode 100644
index 000000000..e78bf9baf
--- /dev/null
+++ b/src/tests/clutter/conform/actor-clone.c
@@ -0,0 +1,68 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include <clutter/clutter.h>
+
+#include "tests/clutter-test-utils.h"
+
+static void
+on_presented (ClutterStage     *stage,
+              CoglFrameEvent   *frame_event,
+              ClutterFrameInfo *frame_info,
+              gboolean         *was_presented)
+{
+  *was_presented = TRUE;
+}
+
+static void
+actor_clone_unmapped (void)
+{
+  ClutterActor *container;
+  ClutterActor *actor;
+  ClutterActor *clone;
+  ClutterActor *stage;
+  gboolean was_presented;
+
+  stage = clutter_test_get_stage ();
+
+  container = clutter_actor_new ();
+  g_object_ref_sink (container);
+  g_object_add_weak_pointer (G_OBJECT (container), (gpointer *) &container);
+
+  actor = clutter_actor_new ();
+  g_object_ref_sink (actor);
+  g_object_add_weak_pointer (G_OBJECT (actor), (gpointer *) &actor);
+
+  clone = clutter_clone_new (actor);
+  g_object_ref_sink (clone);
+  g_object_add_weak_pointer (G_OBJECT (clone), (gpointer *) &clone);
+
+  clutter_actor_hide (container);
+  clutter_actor_hide (actor);
+
+  clutter_actor_add_child (stage, container);
+  clutter_actor_add_child (container, actor);
+  clutter_actor_add_child (stage, clone);
+
+  clutter_actor_set_offscreen_redirect (actor, CLUTTER_OFFSCREEN_REDIRECT_ALWAYS);
+
+  g_signal_connect (stage, "presented", G_CALLBACK (on_presented),
+                    &was_presented);
+
+  clutter_actor_show (stage);
+
+  was_presented = FALSE;
+  while (!was_presented)
+    g_main_context_iteration (NULL, FALSE);
+
+  clutter_actor_destroy (clone);
+  clutter_actor_destroy (actor);
+  clutter_actor_destroy (container);
+  g_assert_null (clone);
+  g_assert_null (actor);
+  g_assert_null (container);
+}
+
+CLUTTER_TEST_SUITE (
+  CLUTTER_TEST_UNIT ("/actor/clone/unmapped", actor_clone_unmapped)
+)
diff --git a/src/tests/clutter/conform/meson.build b/src/tests/clutter/conform/meson.build
index d565934d4..320b00cf4 100644
--- a/src/tests/clutter/conform/meson.build
+++ b/src/tests/clutter/conform/meson.build
@@ -10,6 +10,7 @@ clutter_tests_conform_link_args = [
 
 clutter_conform_tests_actor_tests = [
   'actor-anchors',
+  'actor-clone',
   'actor-destroy',
   'actor-graph',
   'actor-invariants',