[mutter/gnome-3-38] compositor/dnd-actor: Take geometry scale into account on DnD-cancel

[Robert Mader <rmader src gnome org>]

commit 22ab643c568932b8877a12053fe56ba71658785d
Author: Robert Mader <robert mader posteo de>
Date:   Sun Jan 31 17:33:21 2021 +0100

    compositor/dnd-actor: Take geometry scale into account on DnD-cancel
    
    Technically this is still wrong if the source actor or dnd actor are
    transformed in other ways. However geometry scale is the by far most
    common case and we currently lack convenience API in Clutter to
    easily compute the right values.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1683>
    
    (cherry picked from commit 7da34f154b315131d06e6ccb6728600238e1e236)

 src/compositor/meta-dnd-actor.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)
---
diff --git a/src/compositor/meta-dnd-actor.c b/src/compositor/meta-dnd-actor.c
index 31a01db90b..80bffdeb75 100644
--- a/src/compositor/meta-dnd-actor.c
+++ b/src/compositor/meta-dnd-actor.c
@@ -28,6 +28,7 @@
 #include "config.h"
 
 #include "compositor/meta-dnd-actor-private.h"
+#include "compositor/meta-window-actor-private.h"
 
 #include "clutter/clutter.h"
 
@@ -206,16 +207,29 @@ meta_dnd_actor_drag_finish (MetaDnDActor *self,
 
       if (CLUTTER_ACTOR_IS_VISIBLE (self->drag_origin))
         {
+          MetaWindowActor *origin_actor;
           float anchor_x, anchor_y;
           graphene_point_t dest;
+          int origin_geometry_scale;
+          int feedback_geometry_scale;
 
           clutter_actor_get_transformed_position (self->drag_origin,
                                                   &dest.x, &dest.y);
+
+          origin_actor = meta_window_actor_from_actor (self->drag_origin);
+          g_return_if_fail (origin_actor);
+          origin_geometry_scale =
+            meta_window_actor_get_geometry_scale (origin_actor);
+
           meta_feedback_actor_get_anchor (META_FEEDBACK_ACTOR (self),
                                           &anchor_x, &anchor_y);
+          feedback_geometry_scale =
+            meta_feedback_actor_get_geometry_scale (META_FEEDBACK_ACTOR (self));
 
-          dest.x += self->drag_start_x - anchor_x;
-          dest.y += self->drag_start_y - anchor_y;
+          dest.x += ((self->drag_start_x * origin_geometry_scale) -
+                     (anchor_x * feedback_geometry_scale));
+          dest.y += ((self->drag_start_y * origin_geometry_scale) -
+                     (anchor_y * feedback_geometry_scale));
           clutter_actor_set_position (actor, dest.x, dest.y);
         }