third_party/blink/renderer/core/layout/subtree_layout_scope.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * in the documentation and/or other materials provided with the
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_SUBTREE_LAYOUT_SCOPE_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_SUBTREE_LAYOUT_SCOPE_H_

#include "third_party/blink/renderer/core/inspector/inspector_trace_events.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/hash_set.h"

// This is the way to mark a subtree as needing layout during layout,
// e.g. for the purposes of doing a multipass layout.
//
// It should only be used during layout. Outside of layout, you should
// just call layoutObject->setNeedsLayout() directly.
//
// It ensures that you don't accidentally mark part of the tree as
// needing layout and not actually lay it out.

namespace blink {

class LayoutObject;

class SubtreeLayoutScope {
  STACK_ALLOCATED();

 public:
  SubtreeLayoutScope(LayoutObject& root);
  ~SubtreeLayoutScope();

  void SetNeedsLayout(LayoutObject* descendant,
                      LayoutInvalidationReasonForTracing);
  void SetChildNeedsLayout(LayoutObject* descendant);

  LayoutObject& Root() { return root_; }
  void RecordObjectMarkedForLayout(LayoutObject*);

 private:
  LayoutObject& root_;

#if DCHECK_IS_ON()
  HashSet<LayoutObject*> layout_objects_to_layout_;
#endif
};

}  // namespace blink

#endif