Bug 630346 - Use basic layers for windows with transparency r=karlt

widget/gtk2/nsWindow.cpp

@@ -3978,6 +3978,24 @@ nsWindow::EnsureGrabs(void)
         GrabPointer(sRetryGrabTime);
 }
 
+void
+nsWindow::CleanLayerManagerRecursive(void) {
+    if (mLayerManager) {
+        mLayerManager->Destroy();
+        mLayerManager = nullptr;
+    }
+
+    DestroyCompositor();
+
+    GList* children = gdk_window_peek_children(mGdkWindow);
+    for (GList* list = children; list; list = list->next) {
+        nsWindow* window = get_window_for_gdk_window(GDK_WINDOW(list->data));
+        if (window) {
+            window->CleanLayerManagerRecursive();
+        }
+    }
+}
+
 void
 nsWindow::SetTransparencyMode(nsTransparencyMode aMode)
 {
@@ -4016,6 +4034,10 @@ nsWindow::SetTransparencyMode(nsTransparencyMode aMode)
     // need to change anything yet
 
     mIsTransparent = isTransparent;
+
+    // Need to clean our LayerManager up while still alive because
+    // we don't want to use layers acceleration on shaped windows
+    CleanLayerManagerRecursive();
 }
 
 nsTransparencyMode
@@ -6138,6 +6160,20 @@ nsWindow::BeginResizeDrag(nsGUIEvent* aEvent, int32_t aHorizontal, int32_t aVert
     return NS_OK;
 }
 
+nsIWidget::LayerManager*
+nsWindow::GetLayerManager(PLayersChild* aShadowManager,
+                          LayersBackend aBackendHint,
+                          LayerManagerPersistence aPersistence,
+                          bool* aAllowRetaining)
+{
+    if (!mLayerManager && eTransparencyTransparent == GetTransparencyMode()) {
+        mLayerManager = CreateBasicLayerManager();
+    }
+
+    return nsBaseWidget::GetLayerManager(aShadowManager, aBackendHint,
+                                         aPersistence, aAllowRetaining);
+}
+
 void
 nsWindow::ClearCachedResources()
 {

widget/gtk2/nsWindow.h

@@ -442,6 +442,14 @@ private:
 
     void DispatchMissedButtonReleases(GdkEventCrossing *aGdkEvent);
 
+    // nsBaseWidget
+    virtual LayerManager* GetLayerManager(PLayersChild* aShadowManager = nullptr,
+                                          LayersBackend aBackendHint = mozilla::layers::LAYERS_NONE,
+                                          LayerManagerPersistence aPersistence = LAYER_MANAGER_CURRENT,
+                                          bool* aAllowRetaining = nullptr) MOZ_OVERRIDE;
+
+    void CleanLayerManagerRecursive();
+
     /**
      * |mIMModule| takes all IME related stuff.
      *