Pass accurate contentsScale to LayerImpl.

cc/layer_impl.cc

Index: cc/layer_impl.cc
diff --git a/cc/layer_impl.cc b/cc/layer_impl.cc
index 3de9483fccaa6f420319d0fb77bf5b0fd8b1af06..8db5c8b2f553429a1fbdf185e8b279377f51b8cf 100644
--- a/cc/layer_impl.cc
+++ b/cc/layer_impl.cc
@@ -29,6 +29,8 @@ LayerImpl::LayerImpl(int id)
     , m_layerTreeHostImpl(0)
     , m_anchorPoint(0.5, 0.5)
     , m_anchorPointZ(0)
+    , m_contentsScaleX(1.0)
+    , m_contentsScaleY(1.0)
     , m_scrollable(false)
     , m_shouldScrollOnMainThread(false)
     , m_haveWheelEventHandlers(false)
@@ -235,10 +237,8 @@ bool LayerImpl::drawCheckerboardForMissingTiles() const
 
 IntRect LayerImpl::layerRectToContentRect(const WebKit::WebRect& layerRect)
 {
-    float widthScale = static_cast<float>(contentBounds().width()) / bounds().width();
-    float heightScale = static_cast<float>(contentBounds().height()) / bounds().height();
     FloatRect contentRect(layerRect.x, layerRect.y, layerRect.width, layerRect.height);
-    contentRect.scale(widthScale, heightScale);
+    contentRect.scale(contentsScaleX(), contentsScaleY());
     return enclosingIntRect(contentRect);

[danakj, 2012/10/29 20:06:51]

Intersect+comment here too.

[wangxianzhu, 2012/10/30 02:14:21]

Done.

 }
 
@@ -414,6 +414,12 @@ void LayerImpl::setBounds(const IntSize& bounds)
         m_layerPropertyChanged = true;
 }
 
+IntSize LayerImpl::contentBounds() const

[enne (OOO), 2012/10/29 19:19:41]

I don't think this math works out correctly for image layers.  I think you may
need to keep this as a member.

For some values x and y, ceil((x / y) * y) == x + 1, which seems wrong.  I think
LayerImpl::contentBounds() should always equal exactly its
Layer::contentBounds().

[danakj, 2012/10/29 20:06:51]

If contentBounds() is not always equal to ceil(bounds() * contentsScale()), but
sometimes 1 less, then I'm worried that converting rects from layer space to
content space can end up outside the area of the actual contentBounds() for
image layers. I think we need some intersect(), as noted in other comments.

[wangxianzhu, 2012/10/30 02:14:21]

Done.

[wangxianzhu, 2012/10/30 02:14:21]

Done.

+{
+    return IntSize(ceil(bounds().width() * contentsScaleX()),
+                   ceil(bounds().height() * contentsScaleY()));
+}
+
 void LayerImpl::setMaskLayer(scoped_ptr<LayerImpl> maskLayer)
 {
     m_maskLayer = maskLayer.Pass();
@@ -600,12 +606,13 @@ bool LayerImpl::hasDebugBorders() const
     return SkColorGetA(m_debugBorderColor) && debugBorderWidth() > 0;
 }
 
-void LayerImpl::setContentBounds(const IntSize& contentBounds)
+void LayerImpl::setContentsScale(float contentsScaleX, float contentsScaleY)
 {
-    if (m_contentBounds == contentBounds)
+    if (m_contentsScaleX == contentsScaleX && m_contentsScaleY == contentsScaleY)
         return;
 
-    m_contentBounds = contentBounds;
+    m_contentsScaleX = contentsScaleX;
+    m_contentsScaleY = contentsScaleY;
     m_layerPropertyChanged = true;
 }