dnd: Fix issues with drag icons under Wayland

The Wayland dnd surface must remain in place until the drag
is over. Setting it directly as the hardcoded window of the
widget we construct carries the danger that it might get
destroyed prematurely, e.g. when the application calls
gtk_drag_set_icon_name more than once and we recreate the
widget.

Instead, create a dedicated toplevel, and reparent the widget
into it. To keep the code simple, we use the same approach
under X11 as well, and make it the responsibility of the
GDK dnd code to keep the window position updated. We already
pass the current pointer position to gdk_drag_motion, which
makes this very easy.

As a side-effect of these changes, it is now possible to use
non-toplevel widgets as drag icons.

https://bugzilla.gnome.org/show_bug.cgi?id=748763

diff --git a/gtk/gtkdnd.c b/gtk/gtkdnd.c
index d29e2f637041094ec61e1ce8857daf4d1b5a6983..8e673d4f43f3f593fb02fbdaad9e932401d658b8 100644 (file)
--- a/gtk/gtkdnd.c
+++ b/gtk/gtkdnd.c
@@ -96,6 +96,7 @@ struct _GtkDragSourceInfo
   GdkDragAction      possible_actions; /* Actions allowed by source */
   GdkDragContext    *context;     /* drag context */
   GtkWidget         *icon_window; /* Window for drag */
+  GtkWidget         *icon_widget; /* Widget for drag */
   GtkWidget         *fallback_icon; /* Window for drag used on other screens */
   GtkWidget         *ipc_widget;  /* GtkInvisible for grab, message passing */
   GdkCursor         *cursor;      /* Cursor for drag */
@@ -116,7 +117,7 @@ struct _GtkDragSourceInfo
 
   guint              update_idle;      /* Idle function to update the drag */
   guint              drop_timeout;     /* Timeout for aborting drop */
-  guint              destroy_icon : 1; /* If true, destroy icon_window */
+  guint              destroy_icon : 1; /* If true, destroy icon_widget */
   guint              have_grab : 1;    /* Do we still have the pointer grab */
   GtkIconHelper     *icon_helper;
   GdkCursor         *drag_cursors[6];
@@ -2450,6 +2451,7 @@ gtk_drag_begin_internal (GtkWidget          *widget,
   info->last_event = NULL;
   info->selections = NULL;
   info->icon_window = NULL;
+  info->icon_widget = NULL;
   info->destroy_icon = FALSE;
 
   /* Set cur_x, cur_y here so if the "drag-begin" signal shows
@@ -2483,7 +2485,7 @@ gtk_drag_begin_internal (GtkWidget          *widget,
    * application may have set one in ::drag_begin, or it may
    * not have set one.
    */
-  if (!info->icon_window && !info->icon_helper)
+  if (!info->icon_widget && !info->icon_helper)
     {
       if (icon)
         {
@@ -2642,22 +2644,6 @@ gtk_drag_begin (GtkWidget     *widget,
                                   actions, button, event, -1, -1);
 }
 
-static void
-gtk_drag_update_icon (GtkDragSourceInfo *info)
-{
-  if (info->icon_window)
-    {
-      gtk_window_move (GTK_WINDOW (info->icon_window),
-                       info->cur_x - info->hot_x,
-                       info->cur_y - info->hot_y);
-
-      if (gtk_widget_get_visible (info->icon_window))
-        gdk_window_raise (gtk_widget_get_window (info->icon_window));
-      else
-        gtk_widget_show (info->icon_window);
-    }
-}
-
 static void
 gtk_drag_set_icon_window (GdkDragContext *context,
                           GtkWidget      *widget,
@@ -2666,7 +2652,6 @@ gtk_drag_set_icon_window (GdkDragContext *context,
                           gboolean        destroy_on_release)
 {
   GtkDragSourceInfo *info;
-  GdkDisplay *display;
 
   info = gtk_drag_get_source_info (context, FALSE);
   if (info == NULL)
@@ -2679,31 +2664,51 @@ gtk_drag_set_icon_window (GdkDragContext *context,
   gtk_drag_remove_icon (info);
 
   if (widget)
-    g_object_ref (widget);  
-  
-  info->icon_window = widget;
+    g_object_ref (widget);
+
+  info->icon_widget = widget;
   info->hot_x = hot_x;
   info->hot_y = hot_y;
   info->destroy_icon = destroy_on_release;
 
-  display = gdk_window_get_display (gdk_drag_context_get_source_window (context));
+  if (!widget)
+    goto out;
 
-#ifdef GDK_WINDOWING_WAYLAND
-  if (GTK_IS_WINDOW (widget) && GDK_IS_WAYLAND_DISPLAY (display))
+  if (!info->icon_window)
     {
-      if (gtk_widget_get_realized (widget))
-        gtk_widget_unrealize (widget);
+      GdkScreen *screen;
+      GdkVisual *visual;
 
-      gtk_window_set_hardcoded_window (GTK_WINDOW (widget),
-                                       gdk_wayland_drag_context_get_dnd_window (context));
+      screen = gdk_window_get_screen (gdk_drag_context_get_source_window (context));
+      visual = gdk_screen_get_rgba_visual (screen);
+
+      info->icon_window = gtk_window_new (GTK_WINDOW_POPUP);
+      gtk_window_set_type_hint (GTK_WINDOW (info->icon_window), GDK_WINDOW_TYPE_HINT_DND);
+      gtk_window_set_screen (GTK_WINDOW (info->icon_window), screen);
+      gtk_widget_set_size_request (info->icon_window, 24, 24);
+      if (visual)
+        gtk_widget_set_visual (info->icon_window, visual);
+      gtk_widget_set_events (info->icon_window, GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
+      gtk_widget_set_app_paintable (info->icon_window, TRUE);
+      gtk_window_set_hardcoded_window (GTK_WINDOW (info->icon_window),
+                                       gdk_drag_context_get_drag_window (context));
+      gtk_widget_show (info->icon_window);
+    }
+
+  if (GTK_IS_WINDOW (widget))
+    {
+      gtk_widget_hide (widget);
+      gtk_widget_unrealize (widget);
+      gtk_widget_set_parent_window (widget, gtk_widget_get_window (info->icon_window));
+      gtk_widget_show (widget);
     }
-#endif
 
-  if (widget && info->icon_helper)
-    g_clear_object (&info->icon_helper);
+  gtk_container_add (GTK_CONTAINER (info->icon_window), widget);
 
+  g_clear_object (&info->icon_helper);
+
+out:
   gtk_drag_update_cursor (info);
-  gtk_drag_update_icon (info);
 }
 
 /**
@@ -2757,17 +2762,20 @@ set_icon_helper (GdkDragContext     *context,
   gint width, height;
   GdkScreen *screen;
   GdkDisplay *display;
+  GdkVisual *visual;
 
   g_return_if_fail (context != NULL);
   g_return_if_fail (def != NULL);
 
   info = gtk_drag_get_source_info (context, FALSE);
   screen = gdk_window_get_screen (gdk_drag_context_get_source_window (context));
+  visual = gdk_screen_get_rgba_visual (screen);
 
   window = gtk_window_new (GTK_WINDOW_POPUP);
   gtk_window_set_type_hint (GTK_WINDOW (window), GDK_WINDOW_TYPE_HINT_DND);
   gtk_window_set_screen (GTK_WINDOW (window), screen);
-
+  if (visual)
+    gtk_widget_set_visual (window, visual);
   gtk_widget_set_events (window, GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
   gtk_widget_set_app_paintable (window, TRUE);
 
@@ -2827,7 +2835,6 @@ set_icon_helper (GdkDragContext     *context,
           cairo_region_t *region;
 
           surface = cairo_image_surface_create (CAIRO_FORMAT_A1, width, height);
-          
           cr = cairo_create (surface);
           cairo_set_source_surface (cr, source, 0, 0);
           cairo_paint (cr);
@@ -3299,22 +3306,26 @@ gtk_drag_drop_finished (GtkDragSourceInfo *info,
         }
       else
         {
-          GtkDragAnim *anim = g_slice_new0 (GtkDragAnim);
+          GtkDragAnim *anim;
+
+          /* Mark the context as dead, so if the destination decides
+           * to respond really late, we still are OK.
+           */
+          gtk_drag_clear_source_info (info->context);
+
+#ifdef GDK_WINDOWING_WAYLAND
+          if (GDK_IS_WAYLAND_DISPLAY (gtk_widget_get_display (info->widget)))
+            return; /* cancel animation is done by the compositor */ ;
+#endif
+          anim = g_slice_new0 (GtkDragAnim);
           anim->info = info;
           anim->start_time = gdk_frame_clock_get_frame_time (gtk_widget_get_frame_clock (info->widget));
 
           info->cur_screen = gtk_widget_get_screen (info->widget);
 
           if (!info->icon_window)
-            set_icon_helper (info->context, gtk_icon_helper_get_definition (info->icon_helper),
-                             0, 0, TRUE);
+            set_icon_helper (info->context, gtk_icon_helper_get_definition (info->icon_helper), 0, 0, TRUE);
 
-          gtk_drag_update_icon (info);
-
-          /* Mark the context as dead, so if the destination decides
-           * to respond really late, we still are OK.
-           */
-          gtk_drag_clear_source_info (info->context);
           gdk_threads_add_timeout_full (G_PRIORITY_DEFAULT, 17, gtk_drag_anim_timeout, anim, (GDestroyNotify) gtk_drag_anim_destroy);
         }
     }
@@ -3365,12 +3376,12 @@ gtk_drag_drop (GtkDragSourceInfo *info,
               selection_data.target = pair->target;
               selection_data.data = NULL;
               selection_data.length = -1;
-              
+
               g_signal_emit_by_name (info->widget, "drag-data-get",
                                      info->context, &selection_data,
                                      pair->info,
                                      time);
-              
+
               /* FIXME: Should we check for length >= 0 here? */
               gtk_drag_drop_finished (info, GTK_DRAG_RESULT_SUCCESS, time);
               return;
@@ -3383,7 +3394,7 @@ gtk_drag_drop (GtkDragSourceInfo *info,
     {
       if (info->icon_window)
         gtk_widget_hide (info->icon_window);
-        
+
       gdk_drag_drop (info->context, time);
       info->drop_timeout = gdk_threads_add_timeout (DROP_ABORT_TIME,
                                           gtk_drag_abort_timeout,
@@ -3500,12 +3511,12 @@ gtk_drag_anim_timeout (gpointer data)
 static void
 gtk_drag_remove_icon (GtkDragSourceInfo *info)
 {
-  if (info->icon_window)
+  if (info->icon_widget)
     {
-      gtk_widget_hide (info->icon_window);
-      gtk_widget_set_opacity (info->icon_window, 1.0);
+      gtk_widget_hide (info->icon_widget);
+      gtk_widget_set_opacity (info->icon_widget, 1.0);
       if (info->destroy_icon)
-        gtk_widget_destroy (info->icon_window);
+        gtk_widget_destroy (info->icon_widget);
 
       if (info->fallback_icon)
         {
@@ -3513,8 +3524,8 @@ gtk_drag_remove_icon (GtkDragSourceInfo *info)
           info->fallback_icon = NULL;
         }
 
-      g_object_unref (info->icon_window);
-      info->icon_window = NULL;
+      g_object_unref (info->icon_widget);
+      info->icon_widget = NULL;
     }
 }
 
@@ -3557,8 +3568,10 @@ gtk_drag_source_info_destroy (GtkDragSourceInfo *info)
   if (!info->proxy_dest)
     g_signal_emit_by_name (info->widget, "drag-end", info->context);
 
-  if (info->widget)
-    g_object_unref (info->widget);
+  g_clear_object (&info->widget);
+
+  if (info->icon_window)
+    gtk_widget_destroy (info->icon_window);
 
   gtk_selection_remove_all (info->ipc_widget);
   g_object_set_data (G_OBJECT (info->ipc_widget), I_("gtk-info"), NULL);
@@ -3600,7 +3613,7 @@ gtk_drag_update_idle (gpointer data)
                                   info->button, 
                                   info->possible_actions,
                                   &action, &possible_actions);
-      gtk_drag_update_icon (info);
+
       gdk_drag_find_window_for_screen (info->context,
                                        info->icon_window ? gtk_widget_get_window (info->icon_window) : NULL,
                                        info->cur_screen, info->cur_x, info->cur_y,