compositor: Refactor MetaDnD wayland event handling

Hook MetaDnD event delivery in the case of Wayland DnD ops
directly in the Wayland code, instead of indirectly in core/
code.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3420>

src/backends/meta-dnd-private.h

@@ -39,8 +39,9 @@ void meta_dnd_init_xdnd (MetaX11Display *x11_display);
 
 #ifdef HAVE_WAYLAND
 void meta_dnd_wayland_handle_begin_modal (MetaCompositor *compositor);
-void meta_dnd_wayland_handle_end_modal   (MetaCompositor *compositor);
 
-void meta_dnd_wayland_maybe_handle_event (MetaDnd            *dnd,
+void meta_dnd_wayland_handle_end_modal (MetaCompositor *compositor);
-                                          const ClutterEvent *event);
+
+void meta_dnd_wayland_on_motion_event (MetaDnd            *dnd,
+                                       const ClutterEvent *event);
 #endif

src/compositor/meta-compositor-server.c

@@ -44,17 +44,11 @@ meta_compositor_server_monotonic_to_high_res_xserver_time (MetaCompositor *compo
 static void
 meta_compositor_server_grab_begin (MetaCompositor *compositor)
 {
-#ifdef HAVE_WAYLAND
-  meta_dnd_wayland_handle_begin_modal (compositor);
-#endif
 }
 
 static void
 meta_compositor_server_grab_end (MetaCompositor *compositor)
 {
-#ifdef HAVE_WAYLAND
-  meta_dnd_wayland_handle_end_modal (compositor);
-#endif
 }
 
 static MetaCompositorView *

src/compositor/meta-dnd.c

@@ -241,18 +241,7 @@ meta_dnd_handle_xdnd_event (MetaBackend       *backend,
 #endif
 
 #ifdef HAVE_WAYLAND
-static MetaWaylandDataDevice *
+void
-data_device_from_dnd (MetaDnd *dnd)
-{
-  MetaDndPrivate *priv = meta_dnd_get_instance_private (dnd);
-  MetaContext *context = meta_backend_get_context (priv->backend);
-  MetaWaylandCompositor *compositor =
-    meta_context_get_wayland_compositor (context);
-
-  return &compositor->seat->data_device;
-}
-
-static void
 meta_dnd_wayland_on_motion_event (MetaDnd            *dnd,
                                   const ClutterEvent *event)
 {
@@ -264,22 +253,6 @@ meta_dnd_wayland_on_motion_event (MetaDnd            *dnd,
   meta_dnd_notify_dnd_position_change (dnd, (int)event_x, (int)event_y);
 }
 
-void
-meta_dnd_wayland_maybe_handle_event (MetaDnd            *dnd,
-                                     const ClutterEvent *event)
-{
-  MetaWaylandDataDevice *data_device = data_device_from_dnd (dnd);
-  ClutterEventType event_type;
-
-  if (!meta_wayland_data_device_get_current_grab (data_device))
-    return;
-
-  event_type = clutter_event_type (event);
-
-  if (event_type == CLUTTER_MOTION)
-    meta_dnd_wayland_on_motion_event (dnd, event);
-}
-
 void
 meta_dnd_wayland_handle_begin_modal (MetaCompositor *compositor)
 {

src/core/events.c

@@ -456,11 +456,6 @@ meta_display_handle_event (MetaDisplay        *display,
 
   if (stage_has_grab (display))
     {
-#ifdef HAVE_WAYLAND
-      if (wayland_compositor)
-        meta_dnd_wayland_maybe_handle_event (meta_backend_get_dnd (backend), event);
-#endif
-
       bypass_wayland = TRUE;
       bypass_clutter = FALSE;
       goto out;

src/wayland/meta-wayland-data-device.c

@@ -34,6 +34,7 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "backends/meta-dnd-private.h"
 #include "compositor/meta-dnd-actor-private.h"
 #include "core/meta-selection-private.h"
 #include "meta/meta-selection-source-memory.h"
@@ -364,6 +365,8 @@ static void
 data_device_end_drag_grab (MetaWaylandDragGrab *drag_grab)
 {
   MetaWaylandDataDevice *data_device = &drag_grab->seat->data_device;
+  MetaDisplay *display = display_from_data_device (data_device);
+  MetaCompositor *compositor = meta_display_get_compositor (display);
 
   meta_wayland_drag_grab_set_source (drag_grab, NULL);
   meta_wayland_drag_grab_set_focus (drag_grab, NULL);
@@ -397,6 +400,8 @@ data_device_end_drag_grab (MetaWaylandDragGrab *drag_grab)
       drag_grab->handler = NULL;
     }
 
+  meta_dnd_wayland_handle_end_modal (compositor);
+
   g_free (drag_grab);
 }
 
@@ -482,6 +487,10 @@ drag_grab_motion (MetaWaylandEventHandler *handler,
                   gpointer                 user_data)
 {
   MetaWaylandDragGrab *drag_grab = user_data;
+  MetaWaylandCompositor *compositor =
+    meta_wayland_seat_get_compositor (drag_grab->seat);
+  MetaContext *context = meta_wayland_compositor_get_context (compositor);
+  MetaBackend *backend = meta_context_get_backend (context);
   graphene_point_t point;
   uint32_t time_ms;
 
@@ -503,6 +512,8 @@ drag_grab_motion (MetaWaylandEventHandler *handler,
                                   event);
     }
 
+  meta_dnd_wayland_on_motion_event (meta_backend_get_dnd (backend), event);
+
   return CLUTTER_EVENT_STOP;
 }
 
@@ -672,6 +683,8 @@ meta_wayland_data_device_start_drag (MetaWaylandDataDevice           *data_devic
                                      graphene_point_t                 drag_start)
 {
   MetaWaylandSeat *seat = wl_container_of (data_device, seat, data_device);
+  MetaDisplay *display = display_from_data_device (data_device);
+  MetaCompositor *compositor = meta_display_get_compositor (display);
   MetaWaylandDragGrab *drag_grab;
   graphene_point_t pos, surface_pos;
   ClutterModifierType modifiers;
@@ -715,8 +728,6 @@ meta_wayland_data_device_start_drag (MetaWaylandDataDevice           *data_devic
 
   if (icon_surface)
     {
-      MetaDisplay *display = display_from_data_device (data_device);
-      MetaCompositor *compositor = meta_display_get_compositor (display);
       ClutterActor *drag_surface_actor;
 
       drag_grab->drag_surface = icon_surface;
@@ -748,6 +759,8 @@ meta_wayland_data_device_start_drag (MetaWaylandDataDevice           *data_devic
                                              TRUE,
                                              drag_grab);
   meta_wayland_data_source_set_seat (source, seat);
+
+  meta_dnd_wayland_handle_begin_modal (compositor);
 }
 
 void