Source/WebCore/rendering/RenderMultiColumnSet.h

/*
 * Copyright (C) 2012 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
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#ifndef RenderMultiColumnSet_h
#define RenderMultiColumnSet_h

#include "RenderRegionSet.h"

namespace WebCore {

// RenderMultiColumnSet represents a set of columns that all have the same width and height. By combining runs of same-size columns into a single
// object, we significantly reduce the number of unique RenderObjects required to represent columns.
//
// A simple multi-column block will have exactly one RenderMultiColumnSet child. A simple paginated multi-column block will have three
// RenderMultiColumnSet children: one for the content at the bottom of the first page (whose columns will have a shorter height), one
// for the 2nd to n-1 pages, and then one last column set that will hold the shorter columns on the final page (that may have to be balanced
// as well).
//
// Column spans result in the creation of new column sets as well, since a spanning region has to be placed in between the column sets that
// come before and after the span.
class RenderMultiColumnSet : public RenderRegionSet {
public:
    RenderMultiColumnSet(Node*, RenderFlowThread*);
    
    virtual bool isRenderMultiColumnSet() const OVERRIDE { return true; }

    unsigned columnCount() const { return m_columnCount; }
    LayoutUnit columnWidth() const { return m_columnWidth; }
    LayoutUnit columnHeight() const { return m_columnHeight; }

    void setColumnWidthAndCount(LayoutUnit width, unsigned count)
    {
        m_columnWidth = width;
        m_columnCount = count;
    }
    void setColumnHeight(LayoutUnit height)
    {
        m_columnHeight = height;
    }

private:
    virtual void computeLogicalWidth() OVERRIDE;
    virtual void computeLogicalHeight() OVERRIDE;

    virtual LayoutUnit logicalWidthForFlowThreadContent() const OVERRIDE { return m_columnWidth; }
    virtual LayoutUnit logicalHeightForFlowThreadContent() const OVERRIDE { return m_columnHeight; } // FIXME: Will be wrong once we have multiple sets.

    virtual const char* renderName() const;
    
    unsigned m_columnCount;
    LayoutUnit m_columnWidth;
    LayoutUnit m_columnHeight;
};

} // namespace WebCore

#endif // RenderMultiColumnSet_h