2011-03-11 Anders Carlsson <andersca@apple.com>

        Reviewed by Dan Bernstein.

        Don't paint more than 60 times per second
        https://bugs.webkit.org/show_bug.cgi?id=56206
        <rdar://problem/9085989>

        * WebProcess/WebPage/DrawingAreaImpl.cpp:
        (WebKit::DrawingAreaImpl::DrawingAreaImpl):
        Initialize m_lastDisplayTime to 0. Change the display timer to call displayTimerFired.

        (WebKit::DrawingAreaImpl::didUpdate):
        Call displayTimerFired instead of display.

        (WebKit::DrawingAreaImpl::displayTimerFired):
        If we're asked to paint again less than 1/60th of a second after we've already painted,
        defer painting.

        (WebKit::DrawingAreaImpl::display):
        Update m_lastDisplayTime.


git-svn-id: svn://svn.chromium.org/blink/trunk@80875 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/WebKit2/ChangeLog

+2011-03-11  Anders Carlsson  <andersca@apple.com>
+
+        Reviewed by Dan Bernstein.
+
+        Don't paint more than 60 times per second
+        https://bugs.webkit.org/show_bug.cgi?id=56206
+        <rdar://problem/9085989>
+
+        * WebProcess/WebPage/DrawingAreaImpl.cpp:
+        (WebKit::DrawingAreaImpl::DrawingAreaImpl):
+        Initialize m_lastDisplayTime to 0. Change the display timer to call displayTimerFired.
+
+        (WebKit::DrawingAreaImpl::didUpdate):
+        Call displayTimerFired instead of display.
+
+        (WebKit::DrawingAreaImpl::displayTimerFired):
+        If we're asked to paint again less than 1/60th of a second after we've already painted,
+        defer painting.
+
+        (WebKit::DrawingAreaImpl::display):
+        Update m_lastDisplayTime.
+
 2011-03-11  Mark Rowe  <mrowe@apple.com>
 
         Reviewed by Alice Liu.

third_party/WebKit/Source/WebKit2/WebProcess/WebPage/DrawingAreaImpl.cpp

@@ -64,7 +64,8 @@ DrawingAreaImpl::DrawingAreaImpl(WebPage* webPage, const WebPageCreationParamete
     , m_isWaitingForDidUpdate(false)
     , m_isPaintingSuspended(!parameters.isVisible)
     , m_alwaysUseCompositing(false)
-    , m_displayTimer(WebProcess::shared().runLoop(), this, &DrawingAreaImpl::display)
+    , m_lastDisplayTime(0)
+    , m_displayTimer(WebProcess::shared().runLoop(), this, &DrawingAreaImpl::displayTimerFired)
     , m_exitCompositingTimer(WebProcess::shared().runLoop(), this, &DrawingAreaImpl::exitAcceleratedCompositingMode)
 {
     if (webPage->corePage()->settings()->acceleratedDrawingEnabled())
@@ -327,8 +328,8 @@ void DrawingAreaImpl::didUpdate()
 
     m_isWaitingForDidUpdate = false;
 
-    // Display if needed.
-    display();
+    // Display if needed. We call displayTimerFired here since it will throttle updates to 60fps.
+    displayTimerFired();
 }
 
 void DrawingAreaImpl::suspendPainting()
@@ -428,6 +429,21 @@ void DrawingAreaImpl::scheduleDisplay()
     m_displayTimer.startOneShot(0);
 }
 
+void DrawingAreaImpl::displayTimerFired()
+{
+    static const double minimumFrameInterval = 1.0 / 60.0;
+    
+    double timeSinceLastDisplay = currentTime() - m_lastDisplayTime;
+    double timeUntilNextDisplay = minimumFrameInterval - timeSinceLastDisplay;
+
+    if (timeUntilNextDisplay > 0) {
+        m_displayTimer.startOneShot(timeUntilNextDisplay);
+        return;
+    }
+
+    display();
+}
+
 void DrawingAreaImpl::display()
 {
     ASSERT(!m_layerTreeHost);
@@ -534,6 +550,8 @@ void DrawingAreaImpl::display(UpdateInfo& updateInfo)
     // Layout can trigger more calls to setNeedsDisplay and we don't want to process them
     // until the UI process has painted the update, so we stop the timer here.
     m_displayTimer.stop();
+
+    m_lastDisplayTime = currentTime();
 }
 
 

third_party/WebKit/Source/WebKit2/WebProcess/WebPage/DrawingAreaImpl.h

@@ -72,6 +72,7 @@ private:
     void exitAcceleratedCompositingMode();
 
     void scheduleDisplay();
+    void displayTimerFired();
     void display();
     void display(UpdateInfo&);
 
@@ -97,6 +98,8 @@ private:
     bool m_isPaintingSuspended;
     bool m_alwaysUseCompositing;
 
+    double m_lastDisplayTime;
+
     RunLoop::Timer<DrawingAreaImpl> m_displayTimer;
     RunLoop::Timer<DrawingAreaImpl> m_exitCompositingTimer;