x11: Fix damage tracking hack

We are setting mime data with a destroy notify on the cairo
surface to get notified when cairo registers damage for the
surface (in that case, it clears the mime data, calling the
destroy notify). Unfortunately, the destroy notify is also
called when we remove the mime data ourselves, which was
not intentional.

Use a flag in the window impl struct to ignore the callback
when we are clearing the hook.

2 files changed, 20 insertions, 11 deletions

diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 9f189ad626..6106b28d18 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -250,8 +250,10 @@ static void
 on_surface_changed (void *data)
 {
   GdkWindow *window = data;
+  GdkWindowImplX11 *impl = GDK_WINDOW_IMPL_X11 (window->impl);
 
-  window_pre_damage (window);
+  if (impl->tracking_damage)
+    window_pre_damage (window);
 }
 
 /* We want to know when cairo drawing causes damage to the window,
@@ -269,12 +271,15 @@ hook_surface_changed (GdkWindow *window)
   GdkWindowImplX11 *impl = GDK_WINDOW_IMPL_X11 (window->impl);
 
   if (impl->cairo_surface)
-    cairo_surface_set_mime_data (impl->cairo_surface,
-                                 "x-gdk/change-notify",
-                                 (unsigned char *)"X",
-                                 1,
-                                 on_surface_changed,
-                                 window);
+    {
+      cairo_surface_set_mime_data (impl->cairo_surface,
+                                   "x-gdk/change-notify",
+                                   (unsigned char *)"X",
+                                   1,
+                                   on_surface_changed,
+                                   window);
+      impl->tracking_damage = 1;
+    }
 }
 
 static void
@@ -283,10 +288,13 @@ unhook_surface_changed (GdkWindow *window)
   GdkWindowImplX11 *impl = GDK_WINDOW_IMPL_X11 (window->impl);
 
   if (impl->cairo_surface)
-    cairo_surface_set_mime_data (impl->cairo_surface,
-                                 "x-gdk/change-notify",
-                                 NULL, 0,
-                                 NULL, NULL);
+    {
+      impl->tracking_damage = 0;
+      cairo_surface_set_mime_data (impl->cairo_surface,
+                                   "x-gdk/change-notify",
+                                   NULL, 0,
+                                   NULL, NULL);
+    }
 }
 
 static void
diff --git a/gdk/x11/gdkwindow-x11.h b/gdk/x11/gdkwindow-x11.h
index 2bc2417d8b..ed0cbb6cf3 100644
--- a/gdk/x11/gdkwindow-x11.h
+++ b/gdk/x11/gdkwindow-x11.h
@@ -73,6 +73,7 @@ struct _GdkWindowImplX11
   guint override_redirect : 1;
   guint frame_clock_connected : 1;
   guint frame_sync_enabled : 1;
+  guint tracking_damage: 1;
 
   gint window_scale;