Disable prerenders while scrolling

 Bug: 6445656

Change-Id: I3d9e2cece4b3ec86deb00e98ae98f281525dab48

5 files changed, 15 insertions, 10 deletions

diff --git a/Source/WebCore/platform/graphics/android/rendering/SurfaceCollection.cpp b/Source/WebCore/platform/graphics/android/rendering/SurfaceCollection.cpp
index 0bdbf38..7e7a503 100644
--- a/Source/WebCore/platform/graphics/android/rendering/SurfaceCollection.cpp
+++ b/Source/WebCore/platform/graphics/android/rendering/SurfaceCollection.cpp
@@ -83,21 +83,17 @@ SurfaceCollection::~SurfaceCollection()
 #endif
 }
 
-void SurfaceCollection::prepareGL(const SkRect& visibleContentRect)
+void SurfaceCollection::prepareGL(const SkRect& visibleContentRect, bool tryToFastBlit)
 {
     updateLayerPositions(visibleContentRect);
     bool layerTilesDisabled = m_compositedRoot->state()->layersRenderingMode()
         > GLWebViewState::kClippedTextures;
-    bool updateWithBlit = true;
     if (!layerTilesDisabled) {
-        for (unsigned int i = 0; i < m_surfaces.size(); i++) {
-            updateWithBlit &= m_surfaces[i]->canUpdateWithBlit();
-            if (!updateWithBlit)
-                break;
-        }
+        for (unsigned int i = 0; tryToFastBlit && i < m_surfaces.size(); i++)
+            tryToFastBlit &= m_surfaces[i]->canUpdateWithBlit();
     }
     for (unsigned int i = 0; i < m_surfaces.size(); i++)
-        m_surfaces[i]->prepareGL(layerTilesDisabled, updateWithBlit);
+        m_surfaces[i]->prepareGL(layerTilesDisabled, tryToFastBlit);
 }
 
 static inline bool compareSurfaceZ(const Surface* a, const Surface* b)
diff --git a/Source/WebCore/platform/graphics/android/rendering/SurfaceCollection.h b/Source/WebCore/platform/graphics/android/rendering/SurfaceCollection.h
index 5cfd943..18e50ee 100644
--- a/Source/WebCore/platform/graphics/android/rendering/SurfaceCollection.h
+++ b/Source/WebCore/platform/graphics/android/rendering/SurfaceCollection.h
@@ -48,7 +48,7 @@ public:
     virtual ~SurfaceCollection();
 
     // Tiled painting methods (executed on groups)
-    void prepareGL(const SkRect& visibleContentRect);
+    void prepareGL(const SkRect& visibleContentRect, bool tryToFastBlit = false);
     bool drawGL(const SkRect& visibleContentRect);
     Color getBackgroundColor();
     void swapTiles();
diff --git a/Source/WebCore/platform/graphics/android/rendering/SurfaceCollectionManager.cpp b/Source/WebCore/platform/graphics/android/rendering/SurfaceCollectionManager.cpp
index b26be03..7c42bd9 100644
--- a/Source/WebCore/platform/graphics/android/rendering/SurfaceCollectionManager.cpp
+++ b/Source/WebCore/platform/graphics/android/rendering/SurfaceCollectionManager.cpp
@@ -171,7 +171,8 @@ int SurfaceCollectionManager::drawGL(double currentTime, IntRect& viewRect,
 
         m_paintingCollection->evaluateAnimations(currentTime);
 
-        m_paintingCollection->prepareGL(visibleContentRect);
+        bool tryFastBlit = !m_fastSwapMode;
+        m_paintingCollection->prepareGL(visibleContentRect, tryFastBlit);
         m_paintingCollection->computeTexturesAmount(texturesResultPtr);
 
         if (!TilesManager::instance()->useDoubleBuffering() || m_paintingCollection->isReady()) {
diff --git a/Source/WebKit/android/jni/WebViewCore.cpp b/Source/WebKit/android/jni/WebViewCore.cpp
index 1a1fc16..dddae43 100644
--- a/Source/WebKit/android/jni/WebViewCore.cpp
+++ b/Source/WebKit/android/jni/WebViewCore.cpp
@@ -171,6 +171,10 @@ FILE* gRenderTreeFile = 0;
 #include "RenderLayerCompositor.h"
 #endif
 
+// How many ms to wait for the scroll to "settle" before we will consider doing
+// prerenders
+#define PRERENDER_AFTER_SCROLL_DELAY 750
+
 ////////////////////////////////////////////////////////////////////////////////////////////////
 
 namespace android {
@@ -737,6 +741,8 @@ void WebViewCore::paintContents(WebCore::GraphicsContext* gc, WebCore::IntRect&
 
 SkCanvas* WebViewCore::createPrerenderCanvas(PrerenderedInval* prerendered)
 {
+    if (currentTimeMS() - m_scrollSetTime < PRERENDER_AFTER_SCROLL_DELAY)
+        return 0;
     if (prerendered->area.isEmpty())
         return 0;
     FloatRect scaleTemp(m_scrollOffsetX, m_scrollOffsetY, m_screenWidth, m_screenHeight);
@@ -1049,6 +1055,7 @@ void WebViewCore::setScrollOffset(bool sendScrollEvent, int dx, int dy)
     if (m_scrollOffsetX != dx || m_scrollOffsetY != dy) {
         m_scrollOffsetX = dx;
         m_scrollOffsetY = dy;
+        m_scrollSetTime = currentTimeMS();
         // The visible rect is located within our coordinate space so it
         // contains the actual scroll position. Setting the location makes hit
         // testing work correctly.
diff --git a/Source/WebKit/android/jni/WebViewCore.h b/Source/WebKit/android/jni/WebViewCore.h
index 8dc1d07..043953b 100644
--- a/Source/WebKit/android/jni/WebViewCore.h
+++ b/Source/WebKit/android/jni/WebViewCore.h
@@ -760,6 +760,7 @@ namespace android {
         int m_maxYScroll;
         int m_scrollOffsetX; // webview.java's current scroll in X
         int m_scrollOffsetY; // webview.java's current scroll in Y
+        double m_scrollSetTime; // when the scroll was last set
         WebCore::IntPoint m_mousePos;
         int m_screenWidth; // width of the visible rect in document coordinates
         int m_screenHeight;// height of the visible rect in document coordinates