Don't restart the ImageQualityController timer unless it is already half over.

third_party/WebKit/Source/core/layout/ImageQualityController.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 14 matching lines @@
  * 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.
  */
 
 #include "core/layout/ImageQualityController.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
+#include "core/page/ChromeClient.h"
+#include "core/page/Page.h"
 
 namespace blink {
 
-static const double cLowQualityTimeThreshold = 0.500; // 500 ms
+const double ImageQualityController::cLowQualityTimeThreshold = 0.500; // 500 ms
+const double ImageQualityController::cTimerRestartThreshold = 0.250; // 250 ms
 
 static ImageQualityController* gImageQualityController = nullptr;
 
 ImageQualityController* ImageQualityController::imageQualityController()
 {
     if (!gImageQualityController)
         gImageQualityController = new ImageQualityController;
 
     return gImageQualityController;
 }
@@ skipping 15 matching lines @@
 }
 
 InterpolationQuality ImageQualityController::chooseInterpolationQuality(const LayoutObject& object, Image* image, const void* layer, const LayoutSize& layoutSize)
 {
     if (object.style()->imageRendering() == ImageRenderingPixelated)
         return InterpolationNone;
 
     if (InterpolationDefault == InterpolationLow)
         return InterpolationLow;
 
-    if (shouldPaintAtLowQuality(object, image, layer, layoutSize))
+    if (shouldPaintAtLowQuality(object, image, layer, layoutSize, object.frameView()->page()->chromeClient().lastFrameTimeMonotonic()))
         return InterpolationLow;
 
     // For images that are potentially animated we paint them at medium quality.
     if (image && image->maybeAnimated())
         return InterpolationMedium;
 
     return InterpolationDefault;
 }
 
 ImageQualityController::~ImageQualityController()
 {
     // This will catch users of ImageQualityController that forget to call cleanUp.
     ASSERT(!gImageQualityController || gImageQualityController->isEmpty());
 }
 
 ImageQualityController::ImageQualityController()
     : m_timer(adoptPtr(new Timer<ImageQualityController>(this, &ImageQualityController::highQualityRepaintTimerFired)))
+    , m_frameTimeWhenTimerStarted(0.0)
 {
 }
 
 void ImageQualityController::setTimer(Timer<ImageQualityController>* newTimer)
 {
     m_timer = adoptPtr(newTimer);
 }
 
 void ImageQualityController::removeLayer(const LayoutObject& object, LayerSizeMap* innerMap, const void* layer)
 {
@@ skipping 29 matching lines @@
 {
     for (auto& i : m_objectLayerSizeMap) {
         // Only invalidate the object if it is animating.
         if (!i.value.isResizing)
             continue;
 
         // TODO(wangxianzhu): Use LayoutObject::getMutableForPainting().
         const_cast<LayoutObject*>(i.key)->setShouldDoFullPaintInvalidation();
         i.value.isResizing = false;
     }
+    m_frameTimeWhenTimerStarted = 0.0;
 }
 
-void ImageQualityController::restartTimer()
+void ImageQualityController::restartTimer(double lastFrameTimeMonotonic)
 {
-    m_timer->startOneShot(cLowQualityTimeThreshold, BLINK_FROM_HERE);
+    if (!m_timer->isActive() || lastFrameTimeMonotonic == 0.0 || m_frameTimeWhenTimerStarted == 0.0 || (lastFrameTimeMonotonic - m_frameTimeWhenTimerStarted > cTimerRestartThreshold)) {
+        m_timer->startOneShot(cLowQualityTimeThreshold, BLINK_FROM_HERE);
+        m_frameTimeWhenTimerStarted = lastFrameTimeMonotonic;
+    }
 }
 
-bool ImageQualityController::shouldPaintAtLowQuality(const LayoutObject& object, Image* image, const void *layer, const LayoutSize& layoutSize)
+bool ImageQualityController::shouldPaintAtLowQuality(const LayoutObject& object, Image* image, const void *layer, const LayoutSize& layoutSize, double lastFrameTimeMonotonic)
 {
     // If the image is not a bitmap image, then none of this is relevant and we just paint at high
     // quality.
     if (!image || !image->isBitmapImage())
         return false;
 
     if (!layer)
         return false;
 
     if (object.style()->imageRendering() == ImageRenderingOptimizeContrast)
@@ skipping 21 matching lines @@
         // There is no scale in effect. If we had a scale in effect before, we can just remove this object from the list.
         removeLayer(object, innerMap, layer);
         return false;
     }
 
     // If an animated resize is active for this object, paint in low quality and kick the timer ahead.
     if (objectIsResizing) {
         bool sizesChanged = oldSize != layoutSize;
         set(object, innerMap, layer, layoutSize, sizesChanged);
         if (sizesChanged)
-            restartTimer();
+            restartTimer(lastFrameTimeMonotonic);
         return true;
     }
     // If this is the first time resizing this image, or its size is the
     // same as the last resize, draw at high res, but record the paint
     // size and set the timer.
     if (isFirstResize || oldSize == layoutSize) {
-        restartTimer();
+        restartTimer(lastFrameTimeMonotonic);
         set(object, innerMap, layer, layoutSize, false);
         return false;
     }
     // If the timer is no longer active, draw at high quality and don't
     // set the timer.
     if (!m_timer->isActive()) {
         removeLayer(object, innerMap, layer);
         return false;
     }
     // This object has been resized to two different sizes while the timer
     // is active, so draw at low quality, set the flag for animated resizes and
     // the object to the list for high quality redraw.
     set(object, innerMap, layer, layoutSize, true);
-    restartTimer();
+    restartTimer(lastFrameTimeMonotonic);
     return true;
 }
 
 } // namespace blink