webkitgtk-2.16.5HEADwebkitgtk-2.16.5master

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diff --git a/Source/WebCore/page/scrolling/ThreadedScrollingTree.h b/Source/WebCore/page/scrolling/ThreadedScrollingTree.h
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+/*
+ * Copyright (C) 2014-2017 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.
+ */
+
+#pragma once
+
+#if ENABLE(ASYNC_SCROLLING)
+
+#include "ScrollingStateTree.h"
+#include "ScrollingTree.h"
+#include <wtf/RefPtr.h>
+
+namespace WebCore {
+
+class AsyncScrollingCoordinator;
+
+// The ThreadedScrollingTree class lives almost exclusively on the scrolling thread and manages the
+// hierarchy of scrollable regions on the page. It's also responsible for dispatching events
+// to the correct scrolling tree nodes or dispatching events back to the ScrollingCoordinator
+// object on the main thread if they can't be handled on the scrolling thread for various reasons.
+class ThreadedScrollingTree : public ScrollingTree {
+public:
+    virtual ~ThreadedScrollingTree();
+
+    void commitTreeState(std::unique_ptr<ScrollingStateTree>) override;
+
+    void handleWheelEvent(const PlatformWheelEvent&) override;
+
+    // Can be called from any thread. Will try to handle the wheel event on the scrolling thread.
+    // Returns true if the wheel event can be handled on the scrolling thread and false if the
+    // event must be sent again to the WebCore event handler.
+    EventResult tryToHandleWheelEvent(const PlatformWheelEvent&) override;
+
+    void invalidate() override;
+
+protected:
+    explicit ThreadedScrollingTree(AsyncScrollingCoordinator&);
+
+    void scrollingTreeNodeDidScroll(ScrollingNodeID, const FloatPoint& scrollPosition, const std::optional<FloatPoint>& layoutViewportOrigin, ScrollingLayerPositionAction = ScrollingLayerPositionAction::Sync) override;
+    void currentSnapPointIndicesDidChange(ScrollingNodeID, unsigned horizontal, unsigned vertical) override;
+#if PLATFORM(MAC)
+    void handleWheelEventPhase(PlatformWheelEventPhase) override;
+    void setActiveScrollSnapIndices(ScrollingNodeID, unsigned horizontalIndex, unsigned verticalIndex) override;
+    void deferTestsForReason(WheelEventTestTrigger::ScrollableAreaIdentifier, WheelEventTestTrigger::DeferTestTriggerReason) override;
+    void removeTestDeferralForReason(WheelEventTestTrigger::ScrollableAreaIdentifier, WheelEventTestTrigger::DeferTestTriggerReason) override;
+#endif
+
+private:
+    bool isThreadedScrollingTree() const override { return true; }
+
+    RefPtr<AsyncScrollingCoordinator> m_scrollingCoordinator;
+};
+
+} // namespace WebCore
+
+SPECIALIZE_TYPE_TRAITS_SCROLLING_TREE(WebCore::ThreadedScrollingTree, isThreadedScrollingTree())
+
+#endif // ENABLE(ASYNC_SCROLLING)