requestAnimationFrame and Date.now in WebKit

requestAnimationFrame and Date.now in WebKit.md

• requestAnimationFrame()

  • http://trac.webkit.org/browser/trunk/Source/WebCore/dom/Document.cpp?rev=131214#L5544

    int Document::requestAnimationFrame(PassRefPtr<RequestAnimationFrameCallback> callback) {
        return m_scriptedAnimationController->registerCallback(callback);
    }
    

  • http://trac.webkit.org/browser/trunk/Source/WebCore/dom/ScriptedAnimationController.cpp#L104

    ScriptedAnimationController::CallbackId ScriptedAnimationController::registerCallback(PassRefPtr<RequestAnimationFrameCallback> callback) {
        m_callbacks.append(callback);
    }
    

  • http://trac.webkit.org/browser/trunk/Source/WebCore/dom/ScriptedAnimationController.cpp#L214

    void ScriptedAnimationController::animationTimerFired() {
        m_lastAnimationFrameTimeMonotonic = monotonicallyIncreasingTime();
        serviceScriptedAnimations(m_lastAnimationFrameTimeMonotonic);
    }
    

  • http://trac.webkit.org/browser/trunk/Source/WebCore/dom/ScriptedAnimationController.cpp#L130

    void ScriptedAnimationController::serviceScriptedAnimations(double monotonicTimeNow) {
        double highResNowMs = 1000.0 * m_document->loader()->timing().monotonicTimeToZeroBasedDocumentTime(monotonicTimeNow);
        ...
        callback->handleEvent(legacyHighResNowMs); // requestAnimationFrame() に登録した関数がここからコールバックされる
    }
    

• monotonicallyIncreasingTime()

  • http://trac.webkit.org/browser/trunk/Source/WTF/wtf/CurrentTime.cpp#L285

    double monotonicallyIncreasingTime() {
        double currentTimeNow = currentTime();
    }
    

• performance.now()

  • http://trac.webkit.org/browser/trunk/Source/WebCore/page/Performance.cpp#L229

    double Performance::now() const {
        return 1000.0 * m_frame->document()->loader()->timing().monotonicTimeToZeroBasedDocumentTime(monotonicallyIncreasingTime());
    }
    

• Date.now()

  • http://trac.webkit.org/browser/trunk/Source/JavaScriptCore/runtime/DateConstructor.cpp#L204

    EncodedJSValue JSC_HOST_CALL dateNow(ExecState* exec) {
        return JSValue::encode(jsNumber(jsCurrentTime());
    }
    

  • http://trac.webkit.org/browser/trunk/Source/WTF/wtf/DateMath.h#L99

    inline double jsCurrentTime() {
        return floor(WTF::currentTimeMS());
    }
    

  • http://trac.webkit.org/browser/trunk/Source/WTF/wtf/CurrentTime.h#L48

    inline double currentTimeMS() {
        return currentTime() * 1000.0;
    }
    

• currentTime()

  • http://trac.webkit.org/browser/trunk/Source/WTF/wtf/CurrentTime.cpp#L153

  • http://trac.webkit.org/browser/trunk/Source/WTF/wtf/CurrentTime.cpp#L198

    double currentTime() {
        // OSが提供している時間取得APIを呼び出す
        GetTickCount()
        g_get_current_time()
        ecore_time_unix_get()
        gettimeofday()
    }