/* * Copyright (C) 2020 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 #include "NativeWebWheelEvent.h" #include <wtf/Deque.h> #include <wtf/FastMalloc.h> namespace WebKit { class WebWheelEventCoalescer { WTF_MAKE_FAST_ALLOCATED; public: // If this returns true, use nextEventToDispatch() to get the event to dispatch. bool shouldDispatchEvent(const NativeWebWheelEvent&); Optional<WebWheelEvent> nextEventToDispatch(); NativeWebWheelEvent takeOldestEventBeingProcessed(); bool hasEventsBeingProcessed() const { return !m_eventsBeingProcessed.isEmpty(); } void clear(); private: using CoalescedEventSequence = Vector<NativeWebWheelEvent>; static bool canCoalesce(const WebWheelEvent&, const WebWheelEvent&); static WebWheelEvent coalesce(const WebWheelEvent&, const WebWheelEvent&); bool shouldDispatchEventNow(const WebWheelEvent&) const; Deque<NativeWebWheelEvent, 2> m_wheelEventQueue; Deque<std::unique_ptr<CoalescedEventSequence>> m_eventsBeingProcessed; }; } // namespace WebKit