Changeset 143417 in webkit

Timestamp:

Feb 19, 2013, 5:29:39 PM (12 years ago)

Author:

Simon Fraser

Message:

Rubber-banding should not affect the visibleRect of the TileCache
​https://bugs.webkit.org/show_bug.cgi?id=110278

Reviewed by Beth Dakin.

When rubber-banding a slow-scrolling page, or image document, we would constantly re-create
the bottom tile because of the logic that adapts the tile size to the visible rect when slow
scrolling.

Avoid that by ensuring that the visibleRect is not affected by rubber-banding. This is done
via a GraphicsLayerClient function that allows RenderLayerCompositor to provide a custom
position for the scroll layer. We constrain that scroll position to remove the overhang that
results from rubber-banding.

I wasn't able to make a test for this, even with internals.setScrollViewPosition().

• platform/graphics/GraphicsLayerClient.h:

(GraphicsLayerClient):
(WebCore::GraphicsLayerClient::customPositionForVisibleRectComputation):

• platform/graphics/ca/GraphicsLayerCA.cpp:

(WebCore::GraphicsLayerCA::computeVisibleRect):

• rendering/RenderLayerCompositor.cpp:

(WebCore::RenderLayerCompositor::customPositionForVisibleRectComputation):

• rendering/RenderLayerCompositor.h:

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/GraphicsLayerClient.h (modified) (1 diff)
• platform/graphics/ca/GraphicsLayerCA.cpp (modified) (1 diff)
• rendering/RenderLayerCompositor.cpp (modified) (1 diff)
• rendering/RenderLayerCompositor.h (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2013-02-19  Simon Fraser  <simon.fraser@apple.com>
+
+        Rubber-banding should not affect the visibleRect of the TileCache
+        https://bugs.webkit.org/show_bug.cgi?id=110278
+
+        Reviewed by Beth Dakin.
+        
+        When rubber-banding a slow-scrolling page, or image document, we would constantly re-create
+        the bottom tile because of the logic that adapts the tile size to the visible rect when slow
+        scrolling.
+        
+        Avoid that by ensuring that the visibleRect is not affected by rubber-banding. This is done
+        via a GraphicsLayerClient function that allows RenderLayerCompositor to provide a custom
+        position for the scroll layer. We constrain that scroll position to remove the overhang that
+        results from rubber-banding.
+
+        I wasn't able to make a test for this, even with internals.setScrollViewPosition().
+
+        * platform/graphics/GraphicsLayerClient.h:
+        (GraphicsLayerClient):
+        (WebCore::GraphicsLayerClient::customPositionForVisibleRectComputation):
+        * platform/graphics/ca/GraphicsLayerCA.cpp:
+        (WebCore::GraphicsLayerCA::computeVisibleRect):
+        * rendering/RenderLayerCompositor.cpp:
+        (WebCore::RenderLayerCompositor::customPositionForVisibleRectComputation):
+        * rendering/RenderLayerCompositor.h:
+
 2013-02-19  Tony Gentilcore  <tonyg@chromium.org>
 

trunk/Source/WebCore/platform/graphics/GraphicsLayerClient.h

@@ -78 +78 @@
     virtual bool getCurrentTransform(const GraphicsLayer*, TransformationMatrix&) const { return false; }
 
+    // Allows the client to modify a layer position used during the visibleRect calculation, for example to ignore
+    // scroll overhang.
+    virtual void customPositionForVisibleRectComputation(const GraphicsLayer*, FloatPoint&) const { }
+
     // Multiplier for backing store size, related to high DPI.
     virtual float deviceScaleFactor() const { return 1; }

trunk/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp

@@ -918 +918 @@
 
     TransformationMatrix layerTransform;
-    layerTransform.translate(m_position.x(), m_position.y());
+    FloatPoint position = m_position;
+    if (m_client)
+        m_client->customPositionForVisibleRectComputation(this, position);
+
+    layerTransform.translate(position.x(), position.y());
 
     TransformationMatrix currentTransform;

trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp

@@ -303 +303 @@
 }
 
+void RenderLayerCompositor::customPositionForVisibleRectComputation(const GraphicsLayer* graphicsLayer, FloatPoint& position) const
+{
+    if (graphicsLayer != m_scrollLayer.get())
+        return;
+
+    FrameView* frameView = m_renderView ? m_renderView->frameView() : 0;
+    if (!frameView)
+        return;
+
+    FloatPoint scrollPosition = -position;
+    scrollPosition = frameView->constrainScrollPositionForOverhang(roundedIntPoint(scrollPosition));
+    position = -scrollPosition;
+}
+
 void RenderLayerCompositor::scheduleLayerFlush()
 {

trunk/Source/WebCore/rendering/RenderLayerCompositor.h

@@ -250 +250 @@
     // GraphicsLayerUpdaterClient implementation
     virtual void flushLayers(GraphicsLayerUpdater*) OVERRIDE;
+    virtual void customPositionForVisibleRectComputation(const GraphicsLayer*, FloatPoint&) const OVERRIDE;
     
     // Whether the given RL needs a compositing layer.