third_party/WebKit/Source/core/paint/PrePaintTreeWalk.h

// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef PrePaintTreeWalk_h
#define PrePaintTreeWalk_h

#include "core/paint/PaintInvalidator.h"
#include "core/paint/PaintPropertyTreeBuilder.h"

namespace blink {

class FrameView;
class LayoutObject;
struct PrePaintTreeWalkContext;

// This class walks the whole layout tree, beginning from the root FrameView,
// across frame boundaries. Helper classes are called for each tree node to
// perform actual actions.  It expects to be invoked in InPrePaint phase.
class PrePaintTreeWalk {
 public:
  void walk(FrameView& rootFrame);

 private:
  // Throttled rendering (see: FrameView::shouldThrottleRendering()) can prevent
  // updating a subtree. We return true if the subtree was fully walked/updated,
  // and false if the walk was interrupted by throttling.
  bool walk(FrameView&, const PrePaintTreeWalkContext&);
  bool walk(const LayoutObject&, const PrePaintTreeWalkContext&);

  PaintPropertyTreeBuilder m_propertyTreeBuilder;
  PaintInvalidator m_paintInvalidator;
};

}  // namespace blink

#endif  // PrePaintTreeWalk_h