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      1 /*
      2  * Copyright (C) 2012 Apple 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
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 
     27 #ifndef RenderMultiColumnBlock_h
     28 #define RenderMultiColumnBlock_h
     29 
     30 #include "core/rendering/RenderBlock.h"
     31 
     32 namespace WebCore {
     33 
     34 class RenderMultiColumnFlowThread;
     35 
     36 class RenderMultiColumnBlock FINAL : public RenderBlock {
     37 public:
     38     RenderMultiColumnBlock(Element*);
     39 
     40     LayoutUnit columnHeightAvailable() const { return m_columnHeightAvailable; }
     41 
     42     LayoutUnit columnWidth() const { return m_columnWidth; }
     43     unsigned columnCount() const { return m_columnCount; }
     44 
     45     RenderMultiColumnFlowThread* flowThread() const { return m_flowThread; }
     46 
     47     bool requiresBalancing() const { return !m_columnHeightAvailable; }
     48 
     49 private:
     50     virtual bool isRenderMultiColumnBlock() const { return true; }
     51 
     52     virtual const char* renderName() const;
     53 
     54     virtual RenderObject* layoutSpecialExcludedChild(bool relayoutChildren) OVERRIDE;
     55 
     56     virtual void styleDidChange(StyleDifference, const RenderStyle*) OVERRIDE;
     57 
     58     virtual bool updateLogicalWidthAndColumnWidth() OVERRIDE;
     59     virtual void checkForPaginationLogicalHeightChange(LayoutUnit& pageLogicalHeight, bool& pageLogicalHeightChanged, bool& hasSpecifiedPageLogicalHeight) OVERRIDE;
     60     virtual bool relayoutForPagination(bool hasSpecifiedPageLogicalHeight, LayoutUnit pageLogicalHeight, LayoutStateMaintainer&) OVERRIDE;
     61 
     62     virtual void addChild(RenderObject* newChild, RenderObject* beforeChild = 0) OVERRIDE;
     63 
     64     void computeColumnCountAndWidth();
     65 
     66     void ensureColumnSets();
     67 
     68     RenderMultiColumnFlowThread* m_flowThread;
     69     unsigned m_columnCount;   // The default column count/width that are based off our containing block width. These values represent only the default,
     70     LayoutUnit m_columnWidth; // since a multi-column block that is split across variable width pages or regions will have different column counts and widths in each.
     71                               // These values will be cached (eventually) for multi-column blocks.
     72     LayoutUnit m_columnHeightAvailable; // Total height available to columns, or 0 if auto.
     73     bool m_inBalancingPass; // Set when relayouting for column balancing.
     74 };
     75 
     76 inline RenderMultiColumnBlock* toRenderMultiColumnBlock(RenderObject* object)
     77 {
     78     ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderMultiColumnBlock());
     79     return static_cast<RenderMultiColumnBlock*>(object);
     80 }
     81 
     82 inline const RenderMultiColumnBlock* toRenderMultiColumnBlock(const RenderObject* object)
     83 {
     84     ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderMultiColumnBlock());
     85     return static_cast<const RenderMultiColumnBlock*>(object);
     86 }
     87 
     88 // This will catch anyone doing an unnecessary cast.
     89 void toRenderMultiColumnBlock(const RenderMultiColumnBlock*);
     90 
     91 } // namespace WebCore
     92 
     93 #endif // RenderMultiColumnBlock_h
     94 
     95