wayland: Apply GdkDragContext::status action in a delayed manner

In gtkdnd.c, the drag dest event handler will run through all, which may
result in multiple gdk_drag_status() calls along the way if there's
multiple widgets in the hierarchy doing DnD.

This may make us a lot more verbose than desired, so let the wayland
::status handler only cache the result, and commit it after the DnD
event handler traversed the whole tree.

This could be seen on eog, both the window and inner widgets handle DnD,
which result in the selected action ping-ponging between "none" and "copy".

gdk/wayland/gdkdevice-wayland.c

@@ -2247,3 +2247,14 @@ gdk_wayland_device_unset_grab (GdkDevice *gdk_device)
 
   _gdk_wayland_display_deliver_event (gdk_device_get_display (gdk_device), event);
 }
+
+GdkDragContext *
+gdk_wayland_device_get_drop_context (GdkDevice *gdk_device)
+{
+  GdkWaylandDeviceData *device;
+
+  g_return_if_fail (GDK_IS_WAYLAND_DEVICE (gdk_device));
+  device = GDK_WAYLAND_DEVICE (gdk_device)->device;
+
+  return device->drop_context;
+}

gdk/wayland/gdkdisplay-wayland.c

@@ -350,7 +350,7 @@ gdk_registry_handle_global (void               *data,
   else if (strcmp (interface, "wl_data_device_manager") == 0)
     {
       display_wayland->data_device_manager =
-        wl_registry_bind (display_wayland->wl_registry, id, &wl_data_device_manager_interface, 1);
+        wl_registry_bind (display_wayland->wl_registry, id, &wl_data_device_manager_interface, 3);
     }
   else if (strcmp (interface, "wl_subcompositor") == 0)
     {

gdk/wayland/gdkdnd-wayland.c

@@ -43,6 +43,7 @@ struct _GdkWaylandDragContext
   GdkWindow *dnd_window;
   struct wl_surface *dnd_surface;
   struct wl_data_source *data_source;
+  GdkDragAction selected_action;
   uint32_t serial;
   gdouble x;
   gdouble y;
@@ -143,11 +144,30 @@ gdk_wayland_drag_context_find_window (GdkDragContext  *context,
   return NULL;
 }
 
-void
-gdk_wayland_drag_context_set_action (GdkDragContext *context,
-                                     GdkDragAction   action)
+static inline uint32_t
+gdk_to_wl_actions (GdkDragAction action)
 {
-  context->suggested_action = context->action = action;
+  uint32_t dnd_actions = 0;
+
+  if (action & (GDK_ACTION_COPY | GDK_ACTION_LINK | GDK_ACTION_PRIVATE))
+    dnd_actions |= WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY;
+  if (action & GDK_ACTION_MOVE)
+    dnd_actions |= WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE;
+  if (action & GDK_ACTION_ASK)
+    dnd_actions |= WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK;
+
+  return dnd_actions;
+}
+
+void
+gdk_wayland_drag_context_set_actions (GdkDragContext *context,
+                                      GdkDragAction   actions)
+{
+  GdkWaylandDragContext *wayland_context = GDK_WAYLAND_DRAG_CONTEXT (context);
+
+  context->actions = actions;
+  wl_data_source_set_actions (wayland_context->data_source,
+                              gdk_to_wl_actions (actions));
 }
 
 static gboolean
@@ -167,7 +187,7 @@ gdk_wayland_drag_context_drag_motion (GdkDragContext *context,
       _gdk_wayland_drag_context_emit_event (context, GDK_DRAG_STATUS, time);
     }
 
-  gdk_wayland_drag_context_set_action (context, suggested_action);
+  gdk_wayland_drag_context_set_actions (context, possible_actions);
 
   return context->dest_window != NULL;
 }
@@ -196,6 +216,9 @@ gdk_wayland_drop_context_set_status (GdkDragContext *context,
 
   context_wayland = GDK_WAYLAND_DRAG_CONTEXT (context);
 
+  if (!context->dest_window)
+    return;
+
   display = gdk_device_get_display (gdk_drag_context_get_device (context));
   wl_offer = gdk_wayland_selection_get_offer (display,
                                               gdk_drag_get_selection (context));
@@ -231,7 +254,11 @@ gdk_wayland_drag_context_drag_status (GdkDragContext *context,
 				      GdkDragAction   action,
 				      guint32         time_)
 {
-  gdk_wayland_drop_context_set_status (context, action != 0);
+
+  GdkWaylandDragContext *wayland_context;
+
+  wayland_context = GDK_WAYLAND_DRAG_CONTEXT (context);
+  wayland_context->selected_action = action;
 }
 
 static void
@@ -485,3 +512,19 @@ gdk_wayland_drag_context_get_dnd_window (GdkDragContext *context)
   wayland_context = GDK_WAYLAND_DRAG_CONTEXT (context);
   return wayland_context->dnd_window;
 }
+
+void
+gdk_wayland_drag_context_commit_status (GdkDragContext *context)
+{
+  GdkWaylandDragContext *wayland_context;
+  GdkDisplay *display;
+  uint32_t dnd_actions;
+
+  wayland_context = GDK_WAYLAND_DRAG_CONTEXT (context);
+  display = gdk_device_get_display (gdk_drag_context_get_device (context));
+
+  dnd_actions = gdk_to_wl_actions (wayland_context->selected_action);
+  gdk_wayland_selection_set_current_offer_actions (display, dnd_actions);
+
+  gdk_wayland_drop_context_set_status (context, wayland_context->selected_action != 0);
+}

gdk/wayland/gdkprivate-wayland.h

@@ -118,8 +118,8 @@ void _gdk_wayland_drag_context_set_coords (GdkDragContext *context,
                                            gdouble         x,
                                            gdouble         y);
 
-void gdk_wayland_drag_context_set_action (GdkDragContext *context,
-                                          GdkDragAction   action);
+void gdk_wayland_drag_context_set_actions (GdkDragContext *context,
+                                           GdkDragAction   actions);
 
 GdkDragContext * gdk_wayland_drag_context_lookup_by_data_source   (struct wl_data_source *source);
 GdkDragContext * gdk_wayland_drag_context_lookup_by_source_window (GdkWindow *window);
@@ -184,6 +184,7 @@ uint32_t _gdk_wayland_device_get_last_implicit_grab_serial (GdkWaylandDevice  *d
 struct wl_data_device * gdk_wayland_device_get_data_device (GdkDevice *gdk_device);
 void gdk_wayland_device_set_selection (GdkDevice             *gdk_device,
                                        struct wl_data_source *source);
+GdkDragContext * gdk_wayland_device_get_drop_context (GdkDevice *gdk_device);
 
 void gdk_wayland_device_unset_grab       (GdkDevice        *device);
 
@@ -255,6 +256,8 @@ void     gdk_wayland_selection_store   (GdkWindow    *window,
 struct wl_data_source * gdk_wayland_selection_get_data_source (GdkWindow *owner,
                                                                GdkAtom    selection);
 void gdk_wayland_selection_unset_data_source (GdkDisplay *display, GdkAtom selection);
+gboolean gdk_wayland_selection_set_current_offer_actions (GdkDisplay *display,
+                                                          uint32_t    actions);
 
 EGLSurface gdk_wayland_window_get_egl_surface (GdkWindow *window,
                                                EGLConfig config);

gdk/wayland/gdkselection-wayland.c

@@ -350,8 +350,69 @@ data_offer_offer (void                 *data,
   info->targets = g_list_prepend (info->targets, atom);
 }
 
+static inline GdkDragAction
+_wl_to_gdk_actions (uint32_t dnd_actions)
+{
+  GdkDragAction actions = 0;
+
+  if (dnd_actions & WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY)
+    actions |= GDK_ACTION_COPY;
+  if (dnd_actions & WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE)
+    actions |= GDK_ACTION_MOVE;
+  if (dnd_actions & WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK)
+    actions |= GDK_ACTION_ASK;
+
+  return actions;
+}
+
+static void
+data_offer_source_actions (void                 *data,
+                           struct wl_data_offer *wl_data_offer,
+                           uint32_t              source_actions)
+{
+  GdkDeviceManager *device_manager;
+  GdkDragContext *drop_context;
+  GdkDisplay *display;
+  GdkDevice *device;
+
+  display = gdk_display_get_default ();
+  device_manager = gdk_display_get_device_manager (display);
+  device = gdk_device_manager_get_client_pointer (device_manager);
+  drop_context = gdk_wayland_device_get_drop_context (device);
+
+  drop_context->actions = _wl_to_gdk_actions (source_actions);
+
+  if (gdk_drag_context_get_dest_window (drop_context))
+    _gdk_wayland_drag_context_emit_event (drop_context, GDK_DRAG_MOTION,
+                                          GDK_CURRENT_TIME);
+}
+
+static void
+data_offer_action (void                 *data,
+                   struct wl_data_offer *wl_data_offer,
+                   uint32_t              action)
+{
+  GdkDeviceManager *device_manager;
+  GdkDragContext *drop_context;
+  GdkDisplay *display;
+  GdkDevice *device;
+
+  display = gdk_display_get_default ();
+  device_manager = gdk_display_get_device_manager (display);
+  device = gdk_device_manager_get_client_pointer (device_manager);
+  drop_context = gdk_wayland_device_get_drop_context (device);
+
+  drop_context->action = _wl_to_gdk_actions (action);
+
+  if (gdk_drag_context_get_dest_window (drop_context))
+    _gdk_wayland_drag_context_emit_event (drop_context, GDK_DRAG_MOTION,
+                                          GDK_CURRENT_TIME);
+}
+
 static const struct wl_data_offer_listener data_offer_listener = {
   data_offer_offer,
+  data_offer_source_actions,
+  data_offer_action
 };
 
 DataOfferData *
@@ -406,7 +467,6 @@ gdk_wayland_selection_set_offer (GdkDisplay           *display,
   else if (selection_atom == atoms[ATOM_DND])
     selection->dnd_offer = info;
 
-  /* Clear all buffers */
   g_hash_table_remove_all (selection->selection_buffers);
 }
 
@@ -569,6 +629,9 @@ gdk_wayland_selection_store (GdkWindow    *window,
   GdkWaylandSelection *selection = gdk_wayland_display_get_selection (display);
   GArray *array;
 
+  if (type == gdk_atom_intern_static_string ("NULL"))
+    return;
+
   array = g_array_new (TRUE, FALSE, sizeof (guchar));
   g_array_append_vals (array, data, len);
 
@@ -715,18 +778,15 @@ data_source_target (void                  *data,
   if (!mime_type)
     {
       if (context)
-        {
-          gdk_wayland_drag_context_set_action (context, 0);
-          _gdk_wayland_drag_context_emit_event (context, GDK_DRAG_STATUS,
-                                                GDK_CURRENT_TIME);
-        }
+        _gdk_wayland_drag_context_emit_event (context, GDK_DRAG_STATUS,
+                                              GDK_CURRENT_TIME);
+
       return;
     }
 
   if (source == wayland_selection->dnd_source)
     {
       window = wayland_selection->dnd_owner;
-      gdk_wayland_drag_context_set_action (context, GDK_ACTION_COPY);
       _gdk_wayland_drag_context_emit_event (context, GDK_DRAG_STATUS,
                                             GDK_CURRENT_TIME);
     }
@@ -748,7 +808,6 @@ data_source_send (void                  *data,
                   int32_t                fd)
 {
   GdkWaylandSelection *wayland_selection = data;
-  GdkDragContext *context;
   GdkWindow *window;
 
   g_debug (G_STRLOC ": %s source = %p, mime_type = %s, fd = %d",
@@ -760,8 +819,6 @@ data_source_send (void                  *data,
       return;
     }
 
-  context = gdk_wayland_drag_context_lookup_by_data_source (source);
-
   if (source == wayland_selection->dnd_source)
     window = wayland_selection->dnd_owner;
   else if (source == wayland_selection->clipboard_source)
@@ -779,13 +836,6 @@ data_source_send (void                  *data,
                                              gdk_atom_intern (mime_type, FALSE),
                                              fd))
     gdk_wayland_selection_check_write (wayland_selection);
-
-  if (context)
-    {
-      gdk_wayland_device_unset_grab (gdk_drag_context_get_device (context));
-      _gdk_wayland_drag_context_emit_event (context, GDK_DROP_FINISHED,
-                                            GDK_CURRENT_TIME);
-    }
 }
 
 static void
@@ -814,10 +864,62 @@ data_source_cancelled (void                  *data,
     gdk_wayland_selection_unset_data_source (display, atoms[ATOM_CLIPBOARD]);
 }
 
+static void
+data_source_action (void                  *data,
+                    struct wl_data_source *source,
+                    uint32_t               action)
+{
+  GdkDragContext *context;
+
+  g_debug (G_STRLOC ": %s source = %p action=%x",
+           G_STRFUNC, source, action);
+
+  context = gdk_wayland_drag_context_lookup_by_data_source (source);
+
+  if (context)
+    {
+      context->action = _wl_to_gdk_actions (action);
+      _gdk_wayland_drag_context_emit_event (context, GDK_DRAG_STATUS,
+                                            GDK_CURRENT_TIME);
+    }
+}
+
+static void
+data_source_drop_performed (void                  *data,
+                            struct wl_data_source *source)
+{
+}
+
+static void
+data_source_drag_finished (void                  *data,
+                           struct wl_data_source *source)
+{
+  GdkDragContext *context;
+
+  context = gdk_wayland_drag_context_lookup_by_data_source (source);
+
+  if (!context)
+    return;
+
+  if (context->action == GDK_ACTION_MOVE)
+    {
+      gdk_wayland_selection_emit_request (context->source_window,
+                                          atoms[ATOM_DND],
+                                          gdk_atom_intern_static_string ("DELETE"));
+    }
+
+  gdk_wayland_device_unset_grab (gdk_drag_context_get_device (context));
+  _gdk_wayland_drag_context_emit_event (context, GDK_DROP_FINISHED,
+                                        GDK_CURRENT_TIME);
+}
+
 static const struct wl_data_source_listener data_source_listener = {
   data_source_target,
   data_source_send,
-  data_source_cancelled
+  data_source_cancelled,
+  data_source_action,
+  data_source_drop_performed,
+  data_source_drag_finished
 };
 
 struct wl_data_source *
@@ -1015,7 +1117,7 @@ _gdk_wayland_display_convert_selection (GdkDisplay *display,
   offer = gdk_wayland_selection_get_offer (display, selection);
   target_list = gdk_wayland_selection_get_targets (display, selection);
 
-  if (!offer)
+  if (!offer || target == gdk_atom_intern_static_string ("DELETE"))
     {
       GdkEvent *event;
 
@@ -1192,3 +1294,24 @@ gdk_wayland_selection_clear_targets (GdkDisplay *display,
   g_array_set_size (wayland_selection->source_targets, 0);
   gdk_wayland_selection_unset_data_source (display, selection);
 }
+
+gboolean
+gdk_wayland_selection_set_current_offer_actions (GdkDisplay *display,
+                                                 uint32_t    action)
+{
+  struct wl_data_offer *offer;
+  uint32_t all_actions = 0;
+
+  offer = gdk_wayland_selection_get_offer (display, atoms[ATOM_DND]);
+
+  if (!offer)
+    return FALSE;
+
+  if (action != 0)
+    all_actions = WL_DATA_DEVICE_MANAGER_DND_ACTION_COPY |
+      WL_DATA_DEVICE_MANAGER_DND_ACTION_MOVE |
+      WL_DATA_DEVICE_MANAGER_DND_ACTION_ASK;
+
+  wl_data_offer_set_actions (offer, all_actions, action);
+  return TRUE;
+}

gdk/wayland/gdkwaylandselection.h

@@ -52,6 +52,11 @@ GDK_AVAILABLE_IN_ALL
 GdkWindow *
 gdk_wayland_drag_context_get_dnd_window (GdkDragContext *context);
 
+#define gdk_wayland_drag_context_commit_status gdk_wayland_drag_context_commit_status_libgtk_only
+GDK_AVAILABLE_IN_ALL
+void
+gdk_wayland_drag_context_commit_status (GdkDragContext *context);
+
 #endif
 
 G_END_DECLS

gtk/gtkdnd.c

@@ -786,7 +786,7 @@ gtk_drag_can_use_rgba_cursor (GdkDisplay *display,
                               gint        height)
 {
   guint max_width, max_height;
-  
+
   if (!gdk_display_supports_cursor_color (display))
     return FALSE;
 
@@ -805,6 +805,25 @@ gtk_drag_can_use_rgba_cursor (GdkDisplay *display,
   return TRUE;
 }
 
+static gboolean
+gtk_drag_cursor_can_merge_drag_icon (GdkDisplay *display,
+                                     gint        width,
+                                     gint        height)
+{
+#ifdef GDK_WINDOWING_WAYLAND
+  /* On wayland all benefits from merging the drag icon into
+   * the cursor are moot, and furthermore the compositor is
+   * responsible of running any "drag cancelled" animations,
+   * which we won't get for free unless we use the drag
+   * surface.
+   */
+  if (GDK_IS_WAYLAND_DISPLAY (display))
+    return FALSE;
+#endif
+
+  return gtk_drag_can_use_rgba_cursor (display, width, height);
+}
+
 static void
 ensure_drag_cursor_pixbuf (int i)
 {
@@ -927,7 +946,7 @@ gtk_drag_get_cursor (GtkWidget         *widget,
       width = ref_x + MAX (cursor_width - hot_x, icon_width - icon_x);
       height = ref_y + MAX (cursor_height - hot_y, icon_height - icon_y);
 
-      if (gtk_drag_can_use_rgba_cursor (display, width * scale, height * scale))
+      if (gtk_drag_cursor_can_merge_drag_icon (display, width * scale, height * scale))
         {
           cairo_surface_t *surface;
           cairo_t *cr;
@@ -1696,6 +1715,11 @@ _gtk_drag_dest_handle_event (GtkWidget *toplevel,
     default:
       g_assert_not_reached ();
     }
+
+#ifdef GDK_WINDOWING_WAYLAND
+  if (GDK_IS_WAYLAND_DISPLAY (gtk_widget_get_display (toplevel)))
+    gdk_wayland_drag_context_commit_status (context);
+#endif
 }
 
 /**
@@ -3128,7 +3152,7 @@ set_icon_helper (GdkDragContext *context,
                              &width, &height);
 
   if (!force_window &&
-      gtk_drag_can_use_rgba_cursor (display, width + 2, height + 2))
+      gtk_drag_cursor_can_merge_drag_icon (display, width + 2, height + 2))
     {
       GtkDragSourceInfo *info;