Fix blurry content after disabling dev tools emulation

third_party/WebKit/Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 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 3963 matching lines @@
     return;
   m_compositorDeviceScaleFactorOverride = deviceScaleFactor;
   if (m_zoomFactorForDeviceScaleFactor) {
     setZoomLevel(zoomLevel());
     return;
   }
   if (page() && m_layerTreeView)
     updateLayerTreeDeviceScaleFactor();
 }
 
-void WebViewImpl::setRootLayerTransform(const TransformationMatrix& transform) {
-  if (transform == m_rootLayerTransform)
+void WebViewImpl::setDeviceEmulationTransform(
+    const TransformationMatrix& transform) {
+  if (transform == m_deviceEmulationTransform)
     return;
-  m_rootLayerTransform = transform;
-  updateRootLayerTransform();
+  m_deviceEmulationTransform = transform;
+  updateDeviceEmulationTransform();
 }
 
-TransformationMatrix WebViewImpl::getRootLayerTransformForTesting() const {
-  return m_rootLayerTransform;
+TransformationMatrix WebViewImpl::getDeviceEmulationTransformForTesting()
+    const {
+  return m_deviceEmulationTransform;
 }
 
 void WebViewImpl::enableDeviceEmulation(
     const WebDeviceEmulationParams& params) {
   m_devToolsEmulator->enableDeviceEmulation(params);
 }
 
 void WebViewImpl::disableDeviceEmulation() {
   m_devToolsEmulator->disableDeviceEmulation();
 }
@@ skipping 384 matching lines @@
 
   // In SPv2, setRootLayer is used instead.
   DCHECK(!RuntimeEnabledFeatures::slimmingPaintV2Enabled());
 
   VisualViewport& visualViewport = page()->frameHost().visualViewport();
   visualViewport.attachToLayerTree(graphicsLayer);
   if (graphicsLayer) {
     m_rootGraphicsLayer = visualViewport.rootGraphicsLayer();
     m_visualViewportContainerLayer = visualViewport.containerLayer();
     m_rootLayer = m_rootGraphicsLayer->platformLayer();
-    updateRootLayerTransform();
+    updateDeviceEmulationTransform();
     m_layerTreeView->setRootLayer(*m_rootLayer);
     // We register viewport layers here since there may not be a layer
     // tree view prior to this point.
     registerViewportLayersWithCompositor();
 
     // TODO(enne): Work around page visibility changes not being
     // propagated to the WebView in some circumstances.  This needs to
     // be refreshed here when setting a new root layer to avoid being
     // stuck in a presumed incorrectly invisible state.
     m_layerTreeView->setVisible(page()->isPageVisible());
@@ skipping 161 matching lines @@
 void WebViewImpl::updateLayerTreeDeviceScaleFactor() {
   DCHECK(page());
   DCHECK(m_layerTreeView);
 
   float deviceScaleFactor = m_compositorDeviceScaleFactorOverride
                                 ? m_compositorDeviceScaleFactorOverride
                                 : page()->deviceScaleFactor();
   m_layerTreeView->setDeviceScaleFactor(deviceScaleFactor);
 }
 
-void WebViewImpl::updateRootLayerTransform() {
-  if (m_visualViewportContainerLayer)
-    m_visualViewportContainerLayer->setTransform(m_rootLayerTransform);
+void WebViewImpl::updateDeviceEmulationTransform() {
+  if (!m_visualViewportContainerLayer)
+    return;
+
+  // When the device emulation transform is updated, to avoid incorrect
+  // scales and fuzzy raster from the compositor, force all content to
+  // pick ideal raster scales.
+  m_visualViewportContainerLayer->setTransform(m_deviceEmulationTransform);
+  m_layerTreeView->forceRecalculateRasterScales();

[vmpstr, 2016/10/04 00:25:53]

I wonder if this is going to cause inconsistencies in real pages that have
will-change transform and they change the transform so the content is blurry.
Then changing the device type will reset it so that the content is crisp. I
think this is OK. WDYT?

[enne (OOO), 2016/10/04 16:49:21]

Yeah, I also think it is ok to crisp up content here that would have been
blurry.  I think disabling device emulation is an operation that we can jank on
and do a layout / paint / reraster.  Nobody is expecting that operation to run
at 60hz imo.

 }
 
 bool WebViewImpl::detectContentOnTouch(
     const GestureEventWithHitTestResults& targetedEvent) {
   if (!m_page->mainFrame()->isLocalFrame())
     return false;
 
   // Need a local copy of the hit test as
   // setToShadowHostIfInUserAgentShadowRoot() will modify it.
   HitTestResult touchHit = targetedEvent.hitTestResult();
@@ skipping 133 matching lines @@
   if (focusedFrame->localFrameRoot() != mainFrameImpl()->frame())
     return nullptr;
   return focusedFrame;
 }
 
 LocalFrame* WebViewImpl::focusedLocalFrameAvailableForIme() const {
   return m_imeAcceptEvents ? focusedLocalFrameInWidget() : nullptr;
 }
 
 }  // namespace blink