Source/WebCore/rendering/GridLanesLayout.h

/*
 * Copyright (C) 2022 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
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 * 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,
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 */
#pragma once

#include "GridArea.h"
#include "GridTrackSizingAlgorithm.h"
#include "LayoutUnit.h"
#include "RenderBox.h"
#include <wtf/CheckedRef.h>
#include <wtf/WeakPtr.h>

namespace WebCore {

namespace Style {
enum class GridTrackSizingDirection : bool;
}

class RenderGrid;

class GridLanesResult {
public:
    GridLanesResult() = default;
    GridLanesResult(HashMap<SingleThreadWeakRef<const RenderBox>, LayoutUnit>&& stackingAxisOffsets, LayoutUnit gridContentSize)
        : m_stackingAxisOffsets(WTF::move(stackingAxisOffsets))
        , m_gridContentSize(gridContentSize)
    {
    }

    LayoutUnit NODELETE stackingAxisOffsetForGridItem(const RenderBox&) const;

    LayoutUnit gridContentSize() const { return m_gridContentSize; }

private:
    // Offset of the item's margin box.
    HashMap<SingleThreadWeakRef<const RenderBox>, LayoutUnit> m_stackingAxisOffsets;
    LayoutUnit m_gridContentSize;
};

class GridLanesLayout {
public:
    // Construction repopulates the grid, so it has to happen immediately before placement.
    GridLanesLayout(RenderGrid&, unsigned gridAxisTracksCount, Style::GridTrackSizingDirection stackingAxisDirection);

    enum class Phase : uint8_t {
        Layout,
        MinContent,
        MaxContent
    };

    using ResolvedFitTolerance = Variant<LayoutUnit, CSS::Keyword::Infinite>;

    GridLanesResult performGridLanesPlacement(const GridTrackSizingAlgorithm&, ResolvedFitTolerance, Phase);

private:
    GridArea gridAreaForIndefiniteGridAxisItem(const RenderBox& item, ResolvedFitTolerance);
    GridArea gridAreaForDefiniteGridAxisItem(const RenderBox&) const;

    struct StackingAxisPlacement {
        LayoutUnit marginBoxStart;
        LayoutUnit marginBoxEnd;
    };

    GridLanesResult placeGridLanesItems(const GridTrackSizingAlgorithm&, ResolvedFitTolerance, Phase);
    void setItemContainingBlockToGridArea(const GridTrackSizingAlgorithm&, RenderBox&);
    StackingAxisPlacement insertIntoGridAndLayoutItem(const GridTrackSizingAlgorithm&, RenderBox&, const GridArea&, Phase);
    LayoutUnit calculateGridLanesIntrinsicLogicalWidth(RenderBox&, Phase);

    LayoutUnit stackingAxisMarginBoxForItem(const RenderBox& gridItem);
    StackingAxisPlacement updateRunningPositions(const RenderBox& gridItem, const GridArea&);
    LayoutUnit maxRunningPositionForSpan(unsigned startLine, unsigned spanLength) const;
    inline Style::GridTrackSizingDirection NODELETE gridAxisDirection() const;

    unsigned gridAxisTracksCount() const { return static_cast<unsigned>(m_runningPositions.size()); }

    bool hasDefiniteGridAxisPosition(const RenderBox& gridItem, Style::GridTrackSizingDirection gridAxisDirection) const;
    GridArea NODELETE gridAreaFromGridAxisSpan(const GridSpan&) const;
    GridSpan NODELETE gridAxisSpanFromArea(const GridArea&) const;

    Vector<LayoutUnit> m_runningPositions;
    const CheckedRef<RenderGrid> m_renderGrid;
    const LayoutUnit m_stackingAxisGridGap;

    const Style::GridTrackSizingDirection m_stackingAxisDirection;

    unsigned m_autoFlowNextCursor { 0 };
};

} // end namespace WebCore