Drive SVG Animations via requestAnimationFrame

Source/core/svg/graphics/SVGImageChromeClient.cpp

 /*
  * Copyright (C) 2012 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
@@ skipping 17 matching lines @@
 
 #include "config.h"
 #include "core/svg/graphics/SVGImageChromeClient.h"
 
 #include "core/frame/FrameView.h"
 #include "core/svg/graphics/SVGImage.h"
 #include "platform/graphics/ImageObserver.h"
 
 namespace WebCore {
 
+static const double animationFrameDelay = 0.025;

[dstockwell, 2014/03/04 01:19:04]

Is this 40hz, why?

[fs, 2014/03/04 10:28:19]

I used the old value from the SVG animations code here. (To try and avoid
changing too much in one go.) I don't feel strongly about the exact value though
(and would of course rather sync this with some clock, but that's not how
animated Images work in general, and we don't really have anything to key off in
this context.)

+
 SVGImageChromeClient::SVGImageChromeClient(SVGImage* image)
     : m_image(image)
     , m_animationTimer(this, &SVGImageChromeClient::animationTimerFired)
 {
 }
 
 bool SVGImageChromeClient::isSVGImageChromeClient() const
 {
     return true;
 }
@@ skipping 12 matching lines @@
 
 void SVGImageChromeClient::scheduleAnimation()
 {
     // Because a single SVGImage can be shared by multiple pages, we can't key
     // our svg image layout on the page's real animation frame. Therefore, we
     // run this fake animation timer to trigger layout in SVGImages. The name,
     // "animationTimer", is to match the new requestAnimationFrame-based layout
     // approach.
     if (m_animationTimer.isActive())
         return;
-    m_animationTimer.startOneShot(0);
+    // Schedule the 'animation' ASAP if the image does not contain any
+    // animations, but prefer a fixed, jittery, frame-delay if there're any
+    // animations. Checking for pending/active animations could be more
+    // stringent.
+    double fireTime = m_image->hasAnimations() ? animationFrameDelay : 0;
+    m_animationTimer.startOneShot(fireTime);
 }
 
 void SVGImageChromeClient::animationTimerFired(Timer<SVGImageChromeClient>*)
 {
     // In principle, we should call requestAnimationFrame callbacks here, but
     // we know there aren't any because script is forbidden inside SVGImages.
     if (m_image) {
         m_image->frameView()->page()->animator().serviceScriptedAnimations(0);
         m_image->frameView()->updateLayoutAndStyleIfNeededRecursive();
     }
 }
 
 }