Source/WebCore/page/scrolling/ScrollingStatePositionedNode.h

/*
 * Copyright (C) 2019 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``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 ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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#pragma once

#if ENABLE(ASYNC_SCROLLING)

#include "ScrollingConstraints.h"
#include "ScrollingStateNode.h"

#include <wtf/Forward.h>

namespace WebCore {

// ScrollingStatePositionedNode is used to manage the layers for z-order composited descendants of overflow:scroll
// which are not containing block descendants. These layers must have their position inside their ancestor clipping
// layer adjusted on the scrolling thread.
class ScrollingStatePositionedNode final : public ScrollingStateNode {
public:
    static Ref<ScrollingStatePositionedNode> create(ScrollingStateTree&, ScrollingNodeID);

    Ref<ScrollingStateNode> clone(ScrollingStateTree&) override;

    virtual ~ScrollingStatePositionedNode();

    enum {
        RelatedOverflowScrollingNodes = NumStateNodeBits,
        LayoutConstraintData,
    };

    // These are the overflow scrolling nodes whose scroll position affects the layers in this node.
    const Vector<ScrollingNodeID>& relatedOverflowScrollingNodes() const { return m_relatedOverflowScrollingNodes; }
    WEBCORE_EXPORT void setRelatedOverflowScrollingNodes(Vector<ScrollingNodeID>&&);

    WEBCORE_EXPORT void updateConstraints(const LayoutConstraints&);
    const LayoutConstraints& layoutConstraints() const { return m_constraints; }

private:
    ScrollingStatePositionedNode(ScrollingStateTree&, ScrollingNodeID);
    ScrollingStatePositionedNode(const ScrollingStatePositionedNode&, ScrollingStateTree&);

    void setPropertyChangedBitsAfterReattach() override;

    void dumpProperties(WTF::TextStream&, ScrollingStateTreeAsTextBehavior) const override;

    Vector<ScrollingNodeID> m_relatedOverflowScrollingNodes;
    LayoutConstraints m_constraints;
};

} // namespace WebCore

SPECIALIZE_TYPE_TRAITS_SCROLLING_STATE_NODE(ScrollingStatePositionedNode, isPositionedNode())

#endif // ENABLE(ASYNC_SCROLLING)