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/*
* 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. 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
* 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 (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ScrollingStateTree_h
#define ScrollingStateTree_h
#if ENABLE(THREADED_SCROLLING)
#include "ScrollingStateScrollingNode.h"
#include <wtf/OwnPtr.h>
#include <wtf/PassOwnPtr.h>
#include <wtf/RefPtr.h>
namespace WebCore {
// The ScrollingStateTree is a tree that managed ScrollingStateNodes. The nodes keep track of the current
// state of scrolling related properties. Whenever any properties change, the scrolling coordinator
// will be informed and will schedule a timer that will clone the new state tree and send it over to
// the scrolling thread, avoiding locking.
// FIXME: Right now the scrolling thread only ever looks at the root node. In the future, it should
// look at the whole tree and build a ScrollingTree that mimics the ScrollingStateTree.
// FIXME: Right now there is only one type of ScrollingStateNode, which is the ScrollingStateScrollingNode.
// It is currently used for the main frame, but in the future it should be able to be used for subframes
// and overflow areas. In the future, more classes will inherit from ScrollingStateNode, such as
// ScrollingStateFixedNode and ScrollingStateStickyNode for fixed position objects and sticky positoned
// objects, respectively.
class ScrollingStateTree {
public:
static PassOwnPtr<ScrollingStateTree> create();
~ScrollingStateTree();
ScrollingStateScrollingNode* rootStateNode() const { return m_rootStateNode.get(); }
// Copies the current tree state and clears the changed properties mask in the original.
PassOwnPtr<ScrollingStateTree> commit();
void removeNode(ScrollingStateNode*);
void didRemoveNode(ScrollingNodeID);
const Vector<ScrollingNodeID>& removedNodes() const { return m_nodesRemovedSinceLastCommit; }
void setHasChangedProperties(bool changedProperties) { m_hasChangedProperties = changedProperties; }
bool hasChangedProperties() const { return m_hasChangedProperties; }
private:
ScrollingStateTree();
void setRootStateNode(PassOwnPtr<ScrollingStateScrollingNode> rootStateNode) { m_rootStateNode = rootStateNode; }
PassOwnPtr<ScrollingStateTree> clone();
OwnPtr<ScrollingStateScrollingNode> m_rootStateNode;
Vector<ScrollingNodeID> m_nodesRemovedSinceLastCommit;
bool m_hasChangedProperties;
};
} // namespace WebCore
#endif // ENABLE(THREADED_SCROLLING)
#endif // ScrollingStateTree_h
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