/* * Copyright (C) 2014 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 <wtf/RunLoop.h> #include <wtf/Seconds.h> namespace PAL { static const Seconds defaultHysteresisDuration { 5_s }; enum class HysteresisState { Started, Stopped }; class HysteresisActivity { public: explicit HysteresisActivity(WTF::Function<void(HysteresisState)>&& callback = [](HysteresisState) { }, Seconds hysteresisSeconds = defaultHysteresisDuration) : m_callback(WTFMove(callback)) , m_hysteresisSeconds(hysteresisSeconds) , m_active(false) , m_timer(RunLoop::main(), this, &HysteresisActivity::hysteresisTimerFired) { } void start() { if (m_active) return; m_active = true; if (m_timer.isActive()) m_timer.stop(); else m_callback(HysteresisState::Started); } void stop() { if (!m_active) return; m_active = false; m_timer.startOneShot(m_hysteresisSeconds); } void impulse() { if (!m_active) { start(); stop(); } } HysteresisState state() const { return m_active || m_timer.isActive() ? HysteresisState::Started : HysteresisState::Stopped; } private: void hysteresisTimerFired() { m_timer.stop(); m_callback(HysteresisState::Stopped); } WTF::Function<void(HysteresisState)> m_callback; Seconds m_hysteresisSeconds; bool m_active; RunLoop::Timer<HysteresisActivity> m_timer; }; } // namespace PAL