Source/WebCore/rendering/RenderLinesClampSet.h

/*
 * Copyright (C) 2017,2018 Apple Inc.  All rights reserved.
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#pragma once

#include "LayerFragment.h"
#include "RenderLinesClampFlow.h"
#include "RenderMultiColumnSet.h"

namespace WebCore {

class RenderLinesClampSet final : public RenderMultiColumnSet {
    WTF_MAKE_ISO_ALLOCATED(RenderLinesClampSet);
public:
    RenderLinesClampSet(RenderFragmentedFlow&, RenderStyle&&);
    
    bool requiresBalancing() const override { return true; }

    LayoutUnit startPageHeight() const { return m_startPageHeight; }
    LayoutUnit middlePageHeight() const { return m_middlePageHeight; }
    LayoutUnit endPageHeight() const { return m_endPageHeight; }

    LayoutUnit middleObjectHeight() const { return m_middleObjectHeight; }
    void setMiddleObjectHeight(LayoutUnit height) { m_middleObjectHeight = height; }

private:
    bool isRenderLinesClampSet() const override { return true; }

    // Overridden to figure out how to break up the flow into the start/middle/end
    // areas.
    bool recalculateColumnHeight(bool initial) override;

    const char* renderName() const override;
    
    LogicalExtentComputedValues computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop) const override;

    // Lines clamp doesn't support gaps or rules.
    LayoutUnit columnGap() const override { return 0; }
    void paintColumnRules(PaintInfo&, const LayoutPoint&) override { }

    LayoutRect columnRectAt(unsigned index) const override;
    unsigned columnCount() const override;
    unsigned columnIndexAtOffset(LayoutUnit, ColumnIndexCalculationMode = ClampToExistingColumns) const override;
    
    LayoutRect fragmentedFlowPortionRectAt(unsigned index) const override;
    LayoutRect fragmentedFlowPortionOverflowRect(const LayoutRect& fragmentedFlowPortion, unsigned index, unsigned colCount, LayoutUnit colGap) override;

    bool skipLayerFragmentCollectionForColumn(unsigned index) const override { return index == 1; }

    LayoutUnit customBlockProgressionAdjustmentForColumn(unsigned) const override;
    
    LayoutUnit pageLogicalTopForOffset(LayoutUnit) const override;
    LayoutUnit pageLogicalHeightForOffset(LayoutUnit) const override;

private:
    LayoutUnit m_startPageHeight; // Where to clamp the first N lines inside the fragmented flow
    LayoutUnit m_middlePageHeight; // The middle portion of the fragmented flow (does not render).
    LayoutUnit m_endPageHeight; // Where to clamp the last N lines inside the fragmented flow
    
    LayoutUnit m_middleObjectHeight; // The middle object's height plus margins.
};
    
} // namespace WebCore

SPECIALIZE_TYPE_TRAITS_RENDER_OBJECT(RenderLinesClampSet, isRenderLinesClampSet())