Change painting root for squashed layers to the composting container

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1002 matching lines @@
       layers_needing_paint_invalidation.push_back(layers[i].paint_layer);
     }
     layers[i].offset_from_layout_object = new_offset_from_layout_object;
     layers[i].offset_from_layout_object_set = true;
 
     layers[i].paint_layer->SetSubpixelAccumulation(subpixel_accumulation);
   }
 
   squashing_layer->SetPosition(squash_layer_bounds.Location());
   squashing_layer->SetSize(FloatSize(squash_layer_bounds.Size()));
+  LayoutSize offset_from_layout_object_exclude_subpixel_accumulation = squash_layer_origin_in_compositing_container_space - compositing_container->SubpixelAccumulation();
+  DCHECK(offset_from_layout_object_exclude_subpixel_accumulation.Fraction().IsZero());
+  DCHECK_EQ(owning_layer_.EnclosingLayerWithCompositedLayerMapping(kExcludeSelf), compositing_container);
+  squashing_layer->SetOffsetFromLayoutObject(RoundedIntSize(offset_from_layout_object_exclude_subpixel_accumulation), GraphicsLayer::kDontSetNeedsDisplay);
 
   *offset_from_transformed_ancestor =
       compositing_container_offset_from_transformed_ancestor;
   offset_from_transformed_ancestor->Move(
       squash_layer_origin_in_compositing_container_space);
 
   for (size_t i = 0; i < layers.size(); ++i)
     layers[i].local_clip_rect_for_squashed_layer =
         LocalClipRectForSquashedLayer(owning_layer_, layers[i], layers);
 }
@@ skipping 1964 matching lines @@
 }
 
 void CompositedLayerMapping::DoPaintTask(
     const GraphicsLayerPaintInfo& paint_info,
     const GraphicsLayer& graphics_layer,
     const PaintLayerFlags& paint_layer_flags,
     GraphicsContext& context,
     const IntRect& clip /* In the coords of rootLayer */) const {
   FontCachePurgePreventer font_cache_purge_preventer;
 
+  PaintLayer* painting_root = paint_info.paint_layer;
   IntSize offset = paint_info.offset_from_layout_object;
+  if (paint_info.paint_layer->GetCompositingState() == kPaintsIntoGroupedBacking) {
+    painting_root = owning_layer_.EnclosingLayerWithCompositedLayerMapping(kExcludeSelf);
+    offset = graphics_layer.OffsetFromLayoutObject();
+  }
+
   AffineTransform translation;
   translation.Translate(-offset.Width(), -offset.Height());
   TransformRecorder transform_recorder(context, graphics_layer, translation);
 
   // The dirtyRect is in the coords of the painting root.
   IntRect dirty_rect(clip);
   dirty_rect.Move(offset);
 
   if (paint_layer_flags & (kPaintLayerPaintingOverflowContents |
                            kPaintLayerPaintingAncestorClippingMaskPhase)) {
     dirty_rect.Move(
-        RoundedIntSize(paint_info.paint_layer->SubpixelAccumulation()));
+        RoundedIntSize(painting_root->SubpixelAccumulation()));
   } else {
     LayoutRect bounds = paint_info.composited_bounds;
-    bounds.Move(paint_info.paint_layer->SubpixelAccumulation());
+    bounds.Move(painting_root->SubpixelAccumulation());
     dirty_rect.Intersect(PixelSnappedIntRect(bounds));
   }
 
 #if DCHECK_IS_ON()
   if (!GetLayoutObject().View()->GetFrame() ||
       !GetLayoutObject().View()->GetFrame()->ShouldThrottleRendering())
-    paint_info.paint_layer->GetLayoutObject().AssertSubtreeIsLaidOut();
+    painting_root->GetLayoutObject().AssertSubtreeIsLaidOut();
 #endif
 
   float device_scale_factor = blink::DeviceScaleFactorDeprecated(
-      paint_info.paint_layer->GetLayoutObject().GetFrame());
+      painting_root->GetLayoutObject().GetFrame());
   context.SetDeviceScaleFactor(device_scale_factor);
 
   if (paint_info.paint_layer->GetCompositingState() !=
       kPaintsIntoGroupedBacking) {
     // FIXME: GraphicsLayers need a way to split for multicol.
     PaintLayerPaintingInfo painting_info(
-        paint_info.paint_layer, LayoutRect(dirty_rect), kGlobalPaintNormalPhase,
-        paint_info.paint_layer->SubpixelAccumulation());
+        painting_root, LayoutRect(dirty_rect), kGlobalPaintNormalPhase,
+        painting_root->SubpixelAccumulation());
     PaintLayerPainter(*paint_info.paint_layer)
         .PaintLayerContents(context, painting_info, paint_layer_flags);
 
     if (paint_info.paint_layer->ContainsDirtyOverlayScrollbars())
       PaintLayerPainter(*paint_info.paint_layer)
           .PaintLayerContents(
               context, painting_info,
               paint_layer_flags | kPaintLayerPaintingOverlayScrollbars);
   } else {
     PaintLayerPaintingInfo painting_info(
-        paint_info.paint_layer, LayoutRect(dirty_rect), kGlobalPaintNormalPhase,
-        paint_info.paint_layer->SubpixelAccumulation());
+        painting_root, LayoutRect(dirty_rect), kGlobalPaintNormalPhase,
+        painting_root->SubpixelAccumulation());
 
     // PaintLayer::paintLayer assumes that the caller clips to the passed rect.
     // Squashed layers need to do this clipping in software, since there is no
     // graphics layer to clip them precisely. Furthermore, in some cases we
     // squash layers that need clipping in software from clipping ancestors (see
     // CompositedLayerMapping::localClipRectForSquashedLayer()).
     // FIXME: Is it correct to clip to dirtyRect in slimming paint mode?
     // FIXME: Combine similar code here and LayerClipRecorder.
     dirty_rect.Intersect(paint_info.local_clip_rect_for_squashed_layer);
     context.GetPaintController().CreateAndAppend<ClipDisplayItem>(
@@ skipping 540 matching lines @@
   } else if (graphics_layer == decoration_outline_layer_.get()) {
     name = "Decoration Layer";
   } else {
     NOTREACHED();
   }
 
   return name;
 }
 
 }  // namespace blink