Source/WebCore/rendering/RenderMultiColumnFlow.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 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.
 */

#pragma once

#include "RenderFragmentedFlow.h"
#include <wtf/HashMap.h>

namespace WebCore {

class RenderMultiColumnSet;
class RenderMultiColumnSpannerPlaceholder;

class RenderMultiColumnFlow final : public RenderFragmentedFlow {
    WTF_MAKE_ISO_ALLOCATED(RenderMultiColumnFlow);
public:
    RenderMultiColumnFlow(Document&, RenderStyle&&);
    ~RenderMultiColumnFlow();

    RenderBlockFlow* multiColumnBlockFlow() const { return downcast<RenderBlockFlow>(parent()); }

    RenderMultiColumnSet* firstMultiColumnSet() const;
    RenderMultiColumnSet* lastMultiColumnSet() const;
    RenderBox* firstColumnSetOrSpanner() const;
    bool hasColumnSpanner() const { return !m_spannerMap->isEmpty(); }
    static RenderBox* nextColumnSetOrSpannerSiblingOf(const RenderBox*);
    static RenderBox* previousColumnSetOrSpannerSiblingOf(const RenderBox*);

    RenderMultiColumnSpannerPlaceholder* findColumnSpannerPlaceholder(RenderBox* spanner) const;

    void layout() override;

    unsigned columnCount() const { return m_columnCount; }
    LayoutUnit columnWidth() const { return m_columnWidth; }
    LayoutUnit columnHeightAvailable() const { return m_columnHeightAvailable; }
    void setColumnHeightAvailable(LayoutUnit available) { m_columnHeightAvailable = available; }
    bool inBalancingPass() const { return m_inBalancingPass; }
    void setInBalancingPass(bool balancing) { m_inBalancingPass = balancing; }
    bool needsHeightsRecalculation() const { return m_needsHeightsRecalculation; }
    void setNeedsHeightsRecalculation(bool recalculate) { m_needsHeightsRecalculation = recalculate; }

    bool shouldRelayoutForPagination() const { return !m_inBalancingPass && m_needsHeightsRecalculation; }

    void setColumnCountAndWidth(unsigned count, LayoutUnit width)
    {
        m_columnCount = count;
        m_columnWidth = width;
    }

    bool progressionIsInline() const { return m_progressionIsInline; }
    void setProgressionIsInline(bool progressionIsInline) { m_progressionIsInline = progressionIsInline; }

    bool progressionIsReversed() const { return m_progressionIsReversed; }
    void setProgressionIsReversed(bool reversed) { m_progressionIsReversed = reversed; }

    RenderFragmentContainer* mapFromFlowToFragment(TransformState&) const final;

    // This method takes a logical offset and returns a physical translation that can be applied to map
    // a physical point (corresponding to the logical offset) into the fragment's physical coordinate space.
    LayoutSize physicalTranslationOffsetFromFlowToFragment(const RenderFragmentContainer*, const LayoutUnit) const;
    
    // The point is physical, and the result is a physical location within the fragment.
    RenderFragmentContainer* physicalTranslationFromFlowToFragment(LayoutPoint&) const;
    
    // This method is the inverse of the previous method and goes from fragment to flow.
    LayoutSize physicalTranslationFromFragmentToFlow(const RenderMultiColumnSet*, const LayoutPoint&) const;
    
    bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction) override;
    
    void mapAbsoluteToLocalPoint(OptionSet<MapCoordinatesMode>, TransformState&) const override;
    LayoutSize offsetFromContainer(RenderElement&, const LayoutPoint&, bool* offsetDependsOnPoint = nullptr) const override;
    
    // FIXME: Eventually as column and fragment flow threads start nesting, this will end up changing.
    bool shouldCheckColumnBreaks() const override;

    typedef HashMap<RenderBox*, WeakPtr<RenderMultiColumnSpannerPlaceholder>> SpannerMap;
    SpannerMap& spannerMap() { return *m_spannerMap; }

private:
    bool isRenderMultiColumnFlow() const override { return true; }
    const char* renderName() const override;
    void addFragmentToThread(RenderFragmentContainer*) override;
    void willBeRemovedFromTree(IsInternalMove) override;
    void fragmentedFlowDescendantBoxLaidOut(RenderBox*) override;
    LogicalExtentComputedValues computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop) const override;
    LayoutUnit initialLogicalWidth() const override;
    void setPageBreak(const RenderBlock*, LayoutUnit offset, LayoutUnit spaceShortage) override;
    void updateMinimumPageHeight(const RenderBlock*, LayoutUnit offset, LayoutUnit minHeight) override;
    void updateSpaceShortageForSizeContainment(const RenderBlock*, LayoutUnit offset, LayoutUnit shortage) override;
    RenderFragmentContainer* fragmentAtBlockOffset(const RenderBox*, LayoutUnit, bool extendLastFragment = false) const override;
    void setFragmentRangeForBox(const RenderBox&, RenderFragmentContainer*, RenderFragmentContainer*) override;
    bool addForcedFragmentBreak(const RenderBlock*, LayoutUnit, RenderBox* breakChild, bool isBefore, LayoutUnit* offsetBreakAdjustment = 0) override;
    bool isPageLogicalHeightKnown() const override;

private:
    std::unique_ptr<SpannerMap> m_spannerMap;

    // The last set we worked on. It's not to be used as the "current set". The concept of a
    // "current set" is difficult, since layout may jump back and forth in the tree, due to wrong
    // top location estimates (due to e.g. margin collapsing), and possibly for other reasons.
    RenderMultiColumnSet* m_lastSetWorkedOn { nullptr };

    unsigned m_columnCount { 1 }; // The default column count/width that are based off our containing block width. These values represent only the default,
    LayoutUnit m_columnWidth { 0 }; // A multi-column block that is split across variable width pages or fragments will have different column counts and widths in each. These values will be cached (eventually) for multi-column blocks.

    LayoutUnit m_columnHeightAvailable; // Total height available to columns, or 0 if auto.
    bool m_inLayout { false }; // Set while we're laying out the flow thread, during which colum set heights are unknown.
    bool m_inBalancingPass { false }; // Guard to avoid re-entering column balancing.
    bool m_needsHeightsRecalculation { false };
    
    bool m_progressionIsInline { false };
    bool m_progressionIsReversed { false };
};

} // namespace WebCore

SPECIALIZE_TYPE_TRAITS_RENDER_OBJECT(RenderMultiColumnFlow, isRenderMultiColumnFlow())