Bug 1083635. Part 4: Return LayerManager from nsDisplayList::PaintRoot, and dump its contents in nsLayoutUtils::PaintFrame. r=mattwoodrow

--HG--
extra : rebase_source : 8c39aebedb275b56eda4a740b63ae4e00523c206

layout/base/nsDisplayList.cpp

@@ -1283,9 +1283,9 @@ nsDisplayList::ComputeVisibilityForSublist(nsDisplayListBuilder* aBuilder,
  * single layer representing the display list, and then making it the
  * root of the layer manager, drawing into the PaintedLayers.
  */
-void nsDisplayList::PaintRoot(nsDisplayListBuilder* aBuilder,
-                              nsRenderingContext* aCtx,
-                              uint32_t aFlags) {
+already_AddRefed<LayerManager> nsDisplayList::PaintRoot(nsDisplayListBuilder* aBuilder,
+                                                        nsRenderingContext* aCtx,
+                                                        uint32_t aFlags) {
   PROFILER_LABEL("nsDisplayList", "PaintRoot",
     js::ProfileEntry::Category::GRAPHICS);
 
@@ -1311,7 +1311,7 @@ void nsDisplayList::PaintRoot(nsDisplayListBuilder* aBuilder,
   if (!layerManager) {
     if (!aCtx) {
       NS_WARNING("Nowhere to paint into");
-      return;
+      return nullptr;
     }
     layerManager = new BasicLayerManager(BasicLayerManager::BLM_OFFSCREEN);
   }
@@ -1369,7 +1369,7 @@ void nsDisplayList::PaintRoot(nsDisplayListBuilder* aBuilder,
 
   if (!root) {
     layerManager->SetUserData(&gLayerManagerLayerBuilder, oldBuilder);
-    return;
+    return nullptr;
   }
   // Root is being scaled up by the X/Y resolution. Scale it back down.
   root->SetPostScale(1.0f/containerParameters.mXScale,
@@ -1468,6 +1468,7 @@ void nsDisplayList::PaintRoot(nsDisplayListBuilder* aBuilder,
   }
 
   layerManager->SetUserData(&gLayerManagerLayerBuilder, oldBuilder);
+  return layerManager.forget();
 }
 
 uint32_t nsDisplayList::Count() const {

layout/base/nsDisplayList.h

@@ -1657,10 +1657,11 @@ public:
    * If PAINT_COMPRESSED is set, the FrameLayerBuilder should be set to compressed mode
    * to avoid short cut optimizations.
    *
-   * ComputeVisibility must be called before Paint.
-   * 
    * This must only be called on the root display list of the display list
    * tree.
+   *
+   * We return the layer manager used for painting --- mainly so that
+   * callers can dump its layer tree if necessary.
    */
   enum {
     PAINT_DEFAULT = 0,
@@ -1670,8 +1671,9 @@ public:
     PAINT_NO_COMPOSITE = 0x08,
     PAINT_COMPRESSED = 0x10
   };
-  void PaintRoot(nsDisplayListBuilder* aBuilder, nsRenderingContext* aCtx,
-                 uint32_t aFlags);
+  already_AddRefed<LayerManager> PaintRoot(nsDisplayListBuilder* aBuilder,
+                                           nsRenderingContext* aCtx,
+                                           uint32_t aFlags);
   /**
    * Get the bounds. Takes the union of the bounds of all children.
    * The result is not cached.

layout/base/nsLayoutUtils.cpp

@@ -3124,7 +3124,8 @@ nsLayoutUtils::PaintFrame(nsRenderingContext* aRenderingContext, nsIFrame* aFram
     flags |= nsDisplayList::PAINT_COMPRESSED;
   }
 
-  list.PaintRoot(&builder, aRenderingContext, flags);
+  nsRefPtr<LayerManager> layerManager =
+    list.PaintRoot(&builder, aRenderingContext, flags);
 
 #ifdef MOZ_DUMP_PAINTING
   if (gfxUtils::DumpPaintList() || gfxUtils::sDumpPainting) {
@@ -3134,14 +3135,10 @@ nsLayoutUtils::PaintFrame(nsRenderingContext* aRenderingContext, nsIFrame* aFram
     *ss << "Painting --- after optimization:\n";
     nsFrame::PrintDisplayList(&builder, list, *ss, gfxUtils::sDumpPaintingToFile);
 
-    *ss << "Painting --- retained layer tree:\n";
-    nsIWidget* widget = aFrame->GetNearestWidget();
-    if (widget) {
-      nsRefPtr<LayerManager> layerManager = widget->GetLayerManager();
-      if (layerManager) {
-        FrameLayerBuilder::DumpRetainedLayerTree(layerManager, *ss,
-                                                 gfxUtils::sDumpPaintingToFile);
-      }
+    *ss << "Painting --- layer tree:\n";
+    if (layerManager) {
+      FrameLayerBuilder::DumpRetainedLayerTree(layerManager, *ss,
+                                               gfxUtils::sDumpPaintingToFile);
     }
     if (gfxUtils::sDumpPaintingToFile) {
       *ss << "</body></html>";
@@ -3177,12 +3174,6 @@ nsLayoutUtils::PaintFrame(nsRenderingContext* aRenderingContext, nsIFrame* aFram
   }
 
   if (builder.WillComputePluginGeometry()) {
-    nsRefPtr<LayerManager> layerManager;
-    nsIWidget* widget = aFrame->GetNearestWidget();
-    if (widget) {
-      layerManager = widget->GetLayerManager();
-    }
-
     rootPresContext->ComputePluginGeometryUpdates(aFrame, &builder, &list);
 
     // We're not going to get a WillPaintWindow event here if we didn't do

layout/base/nsPresShell.cpp

@@ -5255,7 +5255,9 @@ PresShell::PaintRangePaintInfo(nsTArray<nsAutoPtr<RangePaintInfo> >* aItems,
     ctx->SetMatrix(initialTM.Translate(rootOffset));
     aArea.MoveBy(-rangeInfo->mRootOffset.x, -rangeInfo->mRootOffset.y);
     nsRegion visible(aArea);
-    rangeInfo->mList.PaintRoot(&rangeInfo->mBuilder, &rc, nsDisplayList::PAINT_DEFAULT);
+    nsRefPtr<LayerManager> layerManager =
+        rangeInfo->mList.PaintRoot(&rangeInfo->mBuilder, &rc,
+                                   nsDisplayList::PAINT_DEFAULT);
     aArea.MoveBy(rangeInfo->mRootOffset.x, rangeInfo->mRootOffset.y);
   }