Bug 1464823 - [Wayland] Don't paint until we have a visible wl_surface, r=jhorak,lsalzman

It's based on a solution by Takuro Ashie <ashie@clear-code.com>

MozReview-Commit-ID: FqcdUJQJLdl

--HG--
extra : rebase_source : d4ed4d66439a3693a2f4d5e6a4037ed62969d64f

widget/gtk/mozcontainer.cpp

@@ -212,6 +212,7 @@ moz_container_init (MozContainer *container)
       container->surface = nullptr;
       container->subsurface = nullptr;
       container->eglwindow = nullptr;
+      container->committed = false;
 
       GdkDisplay *gdk_display = gtk_widget_get_display(GTK_WIDGET(container));
       if (GDK_IS_WAYLAND_DISPLAY (gdk_display)) {
@@ -231,12 +232,20 @@ moz_container_init (MozContainer *container)
 }
 
 #if defined(MOZ_WAYLAND)
+static void
+moz_container_after_paint(GdkFrameClock *clock, MozContainer *container)
+{
+    container->committed = true;
+    g_signal_handlers_disconnect_by_func(clock,
+         reinterpret_cast<gpointer>(moz_container_after_paint), container);
+}
+
 /* We want to draw to GdkWindow owned by mContainer from Compositor thread but
  * Gtk+ can be used in main thread only. So we create wayland wl_surface
  * and attach it as an overlay to GdkWindow.
  *
  * see gtk_clutter_embed_ensure_subsurface() at gtk-clutter-embed.c
-*  for reference.
+ * for reference.
  */
 static gboolean
 moz_container_map_surface(MozContainer *container)
@@ -248,6 +257,9 @@ moz_container_map_surface(MozContainer *container)
     static auto sGdkWaylandWindowGetWlSurface =
         (wl_surface *(*)(GdkWindow *))
         dlsym(RTLD_DEFAULT, "gdk_wayland_window_get_wl_surface");
+    static auto sGdkWindowGetFrameClock =
+        (GdkFrameClock *(*)(GdkWindow *))
+        dlsym(RTLD_DEFAULT, "gdk_window_get_frame_clock");
 
     GdkDisplay *display = gtk_widget_get_display(GTK_WIDGET(container));
     if (GDK_IS_X11_DISPLAY(display))
@@ -272,6 +284,11 @@ moz_container_map_surface(MozContainer *container)
           return false;
         }
 
+        GdkFrameClock *clock = sGdkWindowGetFrameClock(window);
+        g_signal_connect_after(clock, "after-paint",
+                               G_CALLBACK(moz_container_after_paint),
+                               container);
+
         container->subsurface =
           wl_subcompositor_get_subsurface (container->subcompositor,
                                            container->surface,
@@ -298,6 +315,7 @@ moz_container_unmap_surface(MozContainer *container)
     g_clear_pointer(&container->eglwindow, wl_egl_window_destroy);
     g_clear_pointer(&container->subsurface, wl_subsurface_destroy);
     g_clear_pointer(&container->surface, wl_surface_destroy);
+    container->committed = false;
 }
 
 #endif
@@ -569,7 +587,7 @@ moz_container_get_wl_surface(MozContainer *container)
         moz_container_map_surface(container);
     }
 
-    return container->surface;
+    return container->committed ? container->surface : nullptr;
 }
 
 struct wl_egl_window *

widget/gtk/mozcontainer.h

@@ -73,6 +73,7 @@ struct _MozContainer
     struct wl_surface       *surface;
     struct wl_subsurface    *subsurface;
     struct wl_egl_window    *eglwindow;
+    gboolean                 committed;
 #endif
 };
 

widget/gtk/nsWindow.cpp

@@ -2067,6 +2067,12 @@ nsWindow::OnExposeEvent(cairo_t *cr)
     if (!mGdkWindow || mIsFullyObscured || !mHasMappedToplevel)
         return FALSE;
 
+#ifdef MOZ_WAYLAND
+    // Window does not have visible wl_surface yet.
+    if (!mIsX11Display && !GetWaylandSurface())
+        return FALSE;
+#endif
+
     nsIWidgetListener *listener = GetListener();
     if (!listener)
         return FALSE;