/* * 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. */ #ifndef HysteresisActivity_h #define HysteresisActivity_h #include "Timer.h" namespace WebCore { static const double DefaultHysteresisSeconds = 5.0; template<typename Delegate> class HysteresisActivity { public: explicit HysteresisActivity(Delegate& delegate, double hysteresisSeconds = DefaultHysteresisSeconds) : m_delegate(delegate) , m_hysteresisSeconds(hysteresisSeconds) , m_active(false) , m_timer(this, &HysteresisActivity<Delegate>::hysteresisTimerFired) { } void start() { if (m_active) return; m_active = true; if (m_timer.isActive()) m_timer.stop(); else m_delegate.started(); } void stop() { if (!m_active) return; m_active = false; m_timer.startOneShot(m_hysteresisSeconds); } void impulse() { if (!m_active) { start(); stop(); } } private: void hysteresisTimerFired(Timer<HysteresisActivity>&) { m_delegate.stopped(); m_timer.stop(); } Delegate& m_delegate; double m_hysteresisSeconds; bool m_active; Timer<HysteresisActivity> m_timer; }; } // namespace WebCore #endif // HysteresisActivity_h