1/*
2 * Copyright (C) 2014-2017 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#if ENABLE(ASYNC_SCROLLING)
29
30#include "ScrollingStateTree.h"
31#include "ScrollingTree.h"
32#include <wtf/Condition.h>
33#include <wtf/RefPtr.h>
34
35namespace WebCore {
36
37class AsyncScrollingCoordinator;
38
39// The ThreadedScrollingTree class lives almost exclusively on the scrolling thread and manages the
40// hierarchy of scrollable regions on the page. It's also responsible for dispatching events
41// to the correct scrolling tree nodes or dispatching events back to the ScrollingCoordinator
42// object on the main thread if they can't be handled on the scrolling thread for various reasons.
43class ThreadedScrollingTree : public ScrollingTree {
44public:
45 virtual ~ThreadedScrollingTree();
46
47 void commitTreeState(std::unique_ptr<ScrollingStateTree>) override;
48
49 ScrollingEventResult handleWheelEvent(const PlatformWheelEvent&) override;
50
51 // Can be called from any thread. Will try to handle the wheel event on the scrolling thread.
52 // Returns true if the wheel event can be handled on the scrolling thread and false if the
53 // event must be sent again to the WebCore event handler.
54 ScrollingEventResult tryToHandleWheelEvent(const PlatformWheelEvent&) override;
55
56 void invalidate() override;
57
58 void incrementPendingCommitCount();
59 void decrementPendingCommitCount();
60
61protected:
62 explicit ThreadedScrollingTree(AsyncScrollingCoordinator&);
63
64 void scrollingTreeNodeDidScroll(ScrollingTreeScrollingNode&, ScrollingLayerPositionAction = ScrollingLayerPositionAction::Sync) override;
65#if PLATFORM(MAC)
66 void handleWheelEventPhase(PlatformWheelEventPhase) override;
67 void setActiveScrollSnapIndices(ScrollingNodeID, unsigned horizontalIndex, unsigned verticalIndex) override;
68 void deferTestsForReason(WheelEventTestTrigger::ScrollableAreaIdentifier, WheelEventTestTrigger::DeferTestTriggerReason) override;
69 void removeTestDeferralForReason(WheelEventTestTrigger::ScrollableAreaIdentifier, WheelEventTestTrigger::DeferTestTriggerReason) override;
70#endif
71
72#if PLATFORM(COCOA)
73 void currentSnapPointIndicesDidChange(ScrollingNodeID, unsigned horizontal, unsigned vertical) override;
74#endif
75
76 void reportExposedUnfilledArea(MonotonicTime, unsigned unfilledArea) override;
77 void reportSynchronousScrollingReasonsChanged(MonotonicTime, SynchronousScrollingReasons) override;
78
79private:
80 bool isThreadedScrollingTree() const override { return true; }
81 void applyLayerPositions() override;
82
83 RefPtr<AsyncScrollingCoordinator> m_scrollingCoordinator;
84
85 void waitForPendingCommits();
86
87 Lock m_pendingCommitCountMutex;
88 unsigned m_pendingCommitCount { 0 };
89 Condition m_commitCondition;
90};
91
92} // namespace WebCore
93
94SPECIALIZE_TYPE_TRAITS_SCROLLING_TREE(WebCore::ThreadedScrollingTree, isThreadedScrollingTree())
95
96#endif // ENABLE(ASYNC_SCROLLING)
97