wayland: Implement the dropping part of DnD

All destination-side events are emitted, and updates to the drop context
are notified through the currently handled wl_data_offer.

https://bugzilla.gnome.org/show_bug.cgi?id=697855

gdk/wayland/gdkdevice-wayland.c

@@ -89,6 +89,7 @@ struct _GdkWaylandDeviceData
   guint cursor_timeout_id;
   guint cursor_image_index;
 
+  GdkDragContext *drop_context;
 
   struct wl_surface *pointer_surface;
 };
@@ -522,10 +523,30 @@ data_device_enter (void                  *data,
                    struct wl_data_offer  *offer)
 {
   GdkWaylandDeviceData *device = (GdkWaylandDeviceData *)data;
+  GdkWindow *dest_window;
+
+  dest_window = wl_surface_get_user_data (surface);
+
+  if (!GDK_IS_WINDOW (dest_window))
+    return;
 
   g_debug (G_STRLOC ": %s data_device = %p serial = %u, surface = %p, x = %d y = %d, offer = %p",
            G_STRFUNC, data_device, serial, surface, x, y, offer);
 
+  /* Update pointer state, so device state queries work during DnD */
+  device->pointer_focus = g_object_ref (dest_window);
+  device->surface_x = wl_fixed_to_double (x);
+  device->surface_y = wl_fixed_to_double (y);
+
+  gdk_wayland_drop_context_update_targets (device->drop_context);
+  _gdk_wayland_drag_context_set_dest_window (device->drop_context,
+                                             dest_window, serial);
+  _gdk_wayland_drag_context_set_coords (device->drop_context,
+                                        wl_fixed_to_double (x),
+                                        wl_fixed_to_double (y));
+  _gdk_wayland_drag_context_emit_event (device->drop_context, GDK_DRAG_ENTER,
+                                        GDK_CURRENT_TIME);
+  gdk_wayland_selection_set_offer (offer);
 }
 
 static void
@@ -537,6 +558,15 @@ data_device_leave (void                  *data,
   g_debug (G_STRLOC ": %s data_device = %p",
            G_STRFUNC, data_device);
 
+  if (!gdk_drag_context_get_dest_window (device->drop_context))
+    return;
+
+  device->pointer_focus = NULL;
+
+  _gdk_wayland_drag_context_set_coords (device->drop_context, -1, -1);
+  _gdk_wayland_drag_context_emit_event (device->drop_context, GDK_DRAG_LEAVE,
+                                        GDK_CURRENT_TIME);
+  _gdk_wayland_drag_context_set_dest_window (device->drop_context, NULL, 0);
 }
 
 static void
@@ -546,16 +576,37 @@ data_device_motion (void                  *data,
                     wl_fixed_t             x,
                     wl_fixed_t             y)
 {
+  GdkWaylandDeviceData *device = (GdkWaylandDeviceData *) data;
+
   g_debug (G_STRLOC ": %s data_device = %p, time = %d, x = %d, y = %d",
            G_STRFUNC, data_device, time, x, y);
+
+  if (!gdk_drag_context_get_dest_window (device->drop_context))
+    return;
+
+  /* Update pointer state, so device state queries work during DnD */
+  device->surface_x = wl_fixed_to_double (x);
+  device->surface_y = wl_fixed_to_double (y);
+
+  gdk_wayland_drop_context_update_targets (device->drop_context);
+  _gdk_wayland_drag_context_set_coords (device->drop_context,
+                                        wl_fixed_to_double (x),
+                                        wl_fixed_to_double (y));
+  _gdk_wayland_drag_context_emit_event (device->drop_context,
+                                        GDK_DRAG_MOTION, time);
 }
 
 static void
 data_device_drop (void                  *data,
                   struct wl_data_device *data_device)
 {
+  GdkWaylandDeviceData *device = (GdkWaylandDeviceData *) data;
+
   g_debug (G_STRLOC ": %s data_device = %p",
            G_STRFUNC, data_device);
+
+  _gdk_wayland_drag_context_emit_event (device->drop_context,
+                                        GDK_DROP_START, GDK_CURRENT_TIME);
 }
 
 static void
@@ -1450,6 +1501,9 @@ seat_handle_capabilities (void                    *data,
       device_manager->devices =
         g_list_prepend (device_manager->devices, device->pointer);
 
+      device->drop_context = _gdk_wayland_drop_context_new (device->pointer,
+                                                            device->data_device);
+
       g_signal_emit_by_name (device_manager, "device-added", device->pointer);
     }
   else if (!(caps & WL_SEAT_CAPABILITY_POINTER) && device->wl_pointer)
@@ -1461,6 +1515,8 @@ seat_handle_capabilities (void                    *data,
       device_manager->devices =
         g_list_remove (device_manager->devices, device->pointer);
 
+      g_clear_object (&device->drop_context);
+
       g_signal_emit_by_name (device_manager, "device-removed", device->pointer);
       g_object_unref (device->pointer);
       device->pointer = NULL;

gdk/wayland/gdkdnd-wayland.c

@@ -40,6 +40,10 @@ typedef struct _GdkWaylandDragContextClass GdkWaylandDragContextClass;
 struct _GdkWaylandDragContext
 {
   GdkDragContext context;
+  struct wl_data_offer *offer;
+  uint32_t serial;
+  gdouble x;
+  gdouble y;
 };
 
 struct _GdkWaylandDragContextClass
@@ -54,13 +58,58 @@ G_DEFINE_TYPE (GdkWaylandDragContext, gdk_wayland_drag_context, GDK_TYPE_DRAG_CO
 static void
 gdk_wayland_drag_context_finalize (GObject *object)
 {
+  GdkWaylandDragContext *wayland_context = GDK_WAYLAND_DRAG_CONTEXT (object);
   GdkDragContext *context = GDK_DRAG_CONTEXT (object);
 
   contexts = g_list_remove (contexts, context);
 
+  if (wayland_context->data_source)
+    wl_data_source_destroy (wayland_context->data_source);
+
+  if (wayland_context->dnd_window)
+    gdk_window_destroy (wayland_context->dnd_window);
+
   G_OBJECT_CLASS (gdk_wayland_drag_context_parent_class)->finalize (object);
 }
 
+void
+_gdk_wayland_drag_context_emit_event (GdkDragContext *context,
+                                      GdkEventType    type,
+                                      guint32         time_)
+{
+  GdkWindow *window;
+  GdkEvent *event;
+
+  switch (type)
+    {
+    case GDK_DRAG_ENTER:
+    case GDK_DRAG_LEAVE:
+    case GDK_DRAG_MOTION:
+    case GDK_DRAG_STATUS:
+    case GDK_DROP_START:
+    case GDK_DROP_FINISHED:
+      break;
+    default:
+      return;
+    }
+
+  if (context->is_source)
+    window = gdk_drag_context_get_source_window (context);
+  else
+    window = gdk_drag_context_get_dest_window (context);
+
+  event = gdk_event_new (type);
+  event->dnd.window = g_object_ref (window);
+  event->dnd.context = g_object_ref (context);
+  event->dnd.time = time_;
+  event->dnd.x_root = GDK_WAYLAND_DRAG_CONTEXT (context)->x;
+  event->dnd.y_root = GDK_WAYLAND_DRAG_CONTEXT (context)->y;
+  gdk_event_set_device (event, gdk_drag_context_get_device (context));
+
+  gdk_event_put (event);
+  gdk_event_free (event);
+}
+
 static GdkWindow *
 gdk_wayland_drag_context_find_window (GdkDragContext  *context,
 				      GdkWindow       *drag_window,
@@ -69,9 +118,29 @@ gdk_wayland_drag_context_find_window (GdkDragContext  *context,
 				      gint             y_root,
 				      GdkDragProtocol *protocol)
 {
+  GdkDevice *device;
+  GdkWindow *window;
+
+  device = gdk_drag_context_get_device (context);
+  window = gdk_device_get_window_at_position (device, NULL, NULL);
+
+  if (window)
+    {
+      window = gdk_window_get_toplevel (window);
+      *protocol = GDK_DRAG_PROTO_WAYLAND;
+      return g_object_ref (window);
+    }
+
   return NULL;
 }
 
+void
+gdk_wayland_drag_context_set_action (GdkDragContext *context,
+                                     GdkDragAction   action)
+{
+  context->suggested_action = context->action = action;
+}
+
 static gboolean
 gdk_wayland_drag_context_drag_motion (GdkDragContext *context,
 				      GdkWindow      *dest_window,
@@ -82,7 +151,16 @@ gdk_wayland_drag_context_drag_motion (GdkDragContext *context,
 				      GdkDragAction   possible_actions,
 				      guint32         time)
 {
-  return FALSE;
+  if (context->dest_window != dest_window)
+    {
+      context->dest_window = dest_window ? g_object_ref (dest_window) : NULL;
+      _gdk_wayland_drag_context_set_coords (context, x_root, y_root);
+      _gdk_wayland_drag_context_emit_event (context, GDK_DRAG_STATUS, time);
+    }
+
+  gdk_wayland_drag_context_set_action (context, suggested_action);
+
+  return context->dest_window != NULL;
 }
 
 static void
@@ -99,11 +177,46 @@ gdk_wayland_drag_context_drag_drop (GdkDragContext *context,
 
 /* Destination side */
 
+static void
+gdk_wayland_drop_context_set_status (GdkDragContext *context,
+                                     gboolean        accepted)
+{
+  GdkWaylandDragContext *context_wayland;
+  struct wl_data_offer *wl_offer;
+
+  context_wayland = GDK_WAYLAND_DRAG_CONTEXT (context);
+  wl_offer = gdk_wayland_selection_get_offer ();
+
+  if (!wl_offer)
+    return;
+
+  if (accepted)
+    {
+      GList *l;
+
+      for (l = context->targets; l; l = l->next)
+        {
+          if (l->data != gdk_atom_intern_static_string ("DELETE"))
+            break;
+        }
+
+      if (l)
+        {
+          wl_data_offer_accept (wl_offer, context_wayland->serial,
+                                gdk_atom_name (l->data));
+          return;
+        }
+    }
+
+  wl_data_offer_accept (wl_offer, context_wayland->serial, NULL);
+}
+
 static void
 gdk_wayland_drag_context_drag_status (GdkDragContext *context,
 				      GdkDragAction   action,
 				      guint32         time_)
 {
+  gdk_wayland_drop_context_set_status (context, action != 0);
 }
 
 static void
@@ -111,6 +224,7 @@ gdk_wayland_drag_context_drop_reply (GdkDragContext *context,
 				     gboolean        accepted,
 				     guint32         time_)
 {
+  gdk_wayland_drop_context_set_status (context, accepted);
 }
 
 static void
@@ -129,13 +243,20 @@ gdk_wayland_drag_context_drop_status (GdkDragContext *context)
 static GdkAtom
 gdk_wayland_drag_context_get_selection (GdkDragContext *context)
 {
-    return GDK_NONE;
+  return gdk_atom_intern_static_string ("GdkWaylandSelection");
 }
 
 static void
-gdk_wayland_drag_context_init (GdkWaylandDragContext *context)
+gdk_wayland_drag_context_init (GdkWaylandDragContext *context_wayland)
 {
+  GdkDragContext *context;
+
+  context = GDK_DRAG_CONTEXT (context_wayland);
   contexts = g_list_prepend (contexts, context);
+
+  context->action = GDK_ACTION_COPY;
+  context->suggested_action = GDK_ACTION_COPY;
+  context->actions = GDK_ACTION_COPY | GDK_ACTION_MOVE;
 }
 
 static void
@@ -160,7 +281,7 @@ gdk_wayland_drag_context_class_init (GdkWaylandDragContextClass *klass)
 GdkDragProtocol
 _gdk_wayland_window_get_drag_protocol (GdkWindow *window, GdkWindow **target)
 {
-  return 0;
+  return GDK_DRAG_PROTO_WAYLAND;
 }
 
 void
@@ -183,3 +304,58 @@ _gdk_wayland_window_drag_begin (GdkWindow *window,
 
   return context;
 }
+
+GdkDragContext *
+_gdk_wayland_drop_context_new (GdkDevice             *device,
+                               struct wl_data_device *data_device)
+{
+  GdkWaylandDragContext *context_wayland;
+  GdkDragContext *context;
+
+  context_wayland = g_object_new (GDK_TYPE_WAYLAND_DRAG_CONTEXT, NULL);
+  context = GDK_DRAG_CONTEXT (context_wayland);
+  context->is_source = FALSE;
+
+  gdk_drag_context_set_device (context, device);
+
+  return context;
+}
+
+void
+gdk_wayland_drop_context_update_targets (GdkDragContext *context)
+{
+  g_list_free (context->targets);
+  context->targets = g_list_copy (gdk_wayland_selection_get_targets ());
+}
+
+void
+_gdk_wayland_drag_context_set_coords (GdkDragContext *context,
+                                      gdouble         x,
+                                      gdouble         y)
+{
+  GdkWaylandDragContext *context_wayland;
+
+  context_wayland = GDK_WAYLAND_DRAG_CONTEXT (context);
+  context_wayland->x = x;
+  context_wayland->y = y;
+}
+
+void
+_gdk_wayland_drag_context_set_source_window (GdkDragContext *context,
+                                             GdkWindow      *window)
+{
+  if (context->source_window)
+    g_object_unref (context->source_window);
+
+  context->source_window = window ? g_object_ref (window) : NULL;
+}
+
+void
+_gdk_wayland_drag_context_set_dest_window (GdkDragContext *context,
+                                           GdkWindow      *dest_window,
+                                           uint32_t        serial)
+{
+  context->dest_window = dest_window ? g_object_ref (dest_window) : NULL;
+  GDK_WAYLAND_DRAG_CONTEXT (context)->serial = serial;
+  gdk_wayland_drop_context_update_targets (context);
+}

gdk/wayland/gdkprivate-wayland.h

@@ -92,6 +92,24 @@ void            _gdk_wayland_window_register_dnd (GdkWindow *window);
 GdkDragContext *_gdk_wayland_window_drag_begin (GdkWindow *window,
 						GdkDevice *device,
 						GList     *targets);
+GdkDragContext * _gdk_wayland_drop_context_new (GdkDevice             *device,
+                                                struct wl_data_device *data_device);
+void _gdk_wayland_drag_context_set_source_window (GdkDragContext *context,
+                                                  GdkWindow      *window);
+void _gdk_wayland_drag_context_set_dest_window (GdkDragContext *context,
+                                                GdkWindow      *dest_window,
+                                                uint32_t        serial);
+void _gdk_wayland_drag_context_emit_event (GdkDragContext *context,
+                                           GdkEventType    type,
+                                           guint32         time_);
+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_drop_context_update_targets (GdkDragContext *context);
 
 void _gdk_wayland_display_create_window_impl (GdkDisplay    *display,
 					      GdkWindow     *window,