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      1 /*
      2  * Copyright (C) 2013 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef SubtreeLayoutScope_h
     32 #define SubtreeLayoutScope_h
     33 
     34 #include "wtf/HashSet.h"
     35 
     36 // This is the way to mark a subtree as needing layout during layout,
     37 // e.g. for the purposes of doing a multipass layout.
     38 //
     39 // It should only be used during layout. Outside of layout, you should
     40 // just call renderer->setNeedsLayout() directly.
     41 //
     42 // It ensures that you don't accidentally mark part of the tree as
     43 // needing layout and not actually lay it out.
     44 
     45 namespace blink {
     46 
     47 class RenderObject;
     48 
     49 class SubtreeLayoutScope {
     50 public:
     51     SubtreeLayoutScope(RenderObject& root);
     52     ~SubtreeLayoutScope();
     53 
     54     void setNeedsLayout(RenderObject* descendant);
     55     void setChildNeedsLayout(RenderObject* descendant);
     56 
     57     RenderObject& root() { return m_root; }
     58     void addRendererToLayout(RenderObject* renderer);
     59 
     60 private:
     61     RenderObject& m_root;
     62 
     63 #if ENABLE(ASSERT)
     64     HashSet<RenderObject*> m_renderersToLayout;
     65 #endif
     66 };
     67 
     68 }
     69 
     70 #endif
     71