[mutter] wayland/dnd-surface: Scale DnD-surface-actor content if necessary

[Jonas Ådahl <jadahl src gnome org>]

commit 25c1a85384980a494c90c8eea53d8cacbfcdd3d3
Author: Robert Mader <robert mader posteo de>
Date:   Fri Sep 6 16:11:03 2019 +0200

    wayland/dnd-surface: Scale DnD-surface-actor content if necessary
    
    Since the recent clutter-content work, legacy scaling (in contrast
    to the new stage-view-scaling) only applies to surfaces that belong
    to a window. This broke scaling of DnD surfaces.
    
    As a workaround, apply the same scaling on DnD-surface-actors until
    we use stage-view-scaling by default and can remove this again.
    
    Also: small corrections of geometry calculation
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/780

 src/wayland/meta-wayland-dnd-surface.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)
---
diff --git a/src/wayland/meta-wayland-dnd-surface.c b/src/wayland/meta-wayland-dnd-surface.c
index 31bd68fd5..2020309a8 100644
--- a/src/wayland/meta-wayland-dnd-surface.c
+++ b/src/wayland/meta-wayland-dnd-surface.c
@@ -29,6 +29,7 @@ struct _MetaWaylandSurfaceRoleDND
   MetaWaylandActorSurface parent;
   int32_t pending_offset_x;
   int32_t pending_offset_y;
+  int geometry_scale;
 };
 
 G_DEFINE_TYPE (MetaWaylandSurfaceRoleDND,
@@ -106,29 +107,29 @@ dnd_subsurface_sync_actor_state (MetaWaylandActorSurface *actor_surface)
     META_WAYLAND_SURFACE_ROLE (actor_surface);
   MetaWaylandSurfaceRoleDND *surface_role_dnd =
     META_WAYLAND_SURFACE_ROLE_DND (surface_role);
-  MetaWaylandSurface *surface =
-    meta_wayland_surface_role_get_surface (surface_role);
   MetaWaylandActorSurfaceClass *actor_surface_class =
     META_WAYLAND_ACTOR_SURFACE_CLASS (meta_wayland_surface_role_dnd_parent_class);
-  float geometry_scale;
-  float actor_scale;
+  int geometry_scale;
   float anchor_x;
   float anchor_y;
-  float new_anchor_x;
-  float new_anchor_y;
 
   g_return_if_fail (META_IS_FEEDBACK_ACTOR (feedback_actor));
 
   geometry_scale =
     meta_wayland_actor_surface_get_geometry_scale (actor_surface);
-  actor_scale = geometry_scale / surface->scale;
 
   meta_feedback_actor_get_anchor (feedback_actor, &anchor_x, &anchor_y);
-  new_anchor_x = anchor_x - surface_role_dnd->pending_offset_x / actor_scale;
-  new_anchor_y = anchor_y - surface_role_dnd->pending_offset_y / actor_scale;
-  meta_feedback_actor_set_anchor (feedback_actor,
-                                  new_anchor_x,
-                                  new_anchor_y);
+  anchor_x -= surface_role_dnd->pending_offset_x * geometry_scale;
+  anchor_y -= surface_role_dnd->pending_offset_y * geometry_scale;
+  meta_feedback_actor_set_anchor (feedback_actor, anchor_x, anchor_y);
+
+  if (surface_role_dnd->geometry_scale != geometry_scale)
+    {
+      surface_role_dnd->geometry_scale = geometry_scale;
+      clutter_actor_set_scale (CLUTTER_ACTOR (surface_actor),
+                               geometry_scale,
+                               geometry_scale);
+    }
 
   actor_surface_class->sync_actor_state (actor_surface);
 }
@@ -136,6 +137,7 @@ dnd_subsurface_sync_actor_state (MetaWaylandActorSurface *actor_surface)
 static void
 meta_wayland_surface_role_dnd_init (MetaWaylandSurfaceRoleDND *role)
 {
+  role->geometry_scale = 1;
 }
 
 static void