Revert http://trac.webkit.org/changeset/150047

It introduced unwanted behavioral differences between
Retina and non-Retina Mac hardware.

* platform/graphics/ca/GraphicsLayerCA.cpp:
(WebCore::GraphicsLayerCA::requiresTiledLayer):
(WebCore::GraphicsLayerCA::computePixelAlignment):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@150135 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
index 6e467be..02490ba 100644
--- a/Source/WebCore/ChangeLog
+++ b/Source/WebCore/ChangeLog
@@ -1,3 +1,14 @@
+2013-05-14  Simon Fraser  <simon.fraser@apple.com>
+
+        Revert http://trac.webkit.org/changeset/150047
+        
+        It introduced unwanted behavioral differences between
+        Retina and non-Retina Mac hardware.
+
+        * platform/graphics/ca/GraphicsLayerCA.cpp:
+        (WebCore::GraphicsLayerCA::requiresTiledLayer):
+        (WebCore::GraphicsLayerCA::computePixelAlignment):
+
 2013-05-15  Darin Adler  <darin@apple.com>
 
         [Mac] Remove the ClipboardMac class and header file
diff --git a/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp b/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp
index 4b11ccd..ffcad87 100644
--- a/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp
+++ b/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp
@@ -2676,10 +2676,8 @@
     if (!m_drawsContent || !m_allowTiledLayer || m_isPageTiledBackingLayer)
         return false;
 
-    float effectiveScale = pageScaleFactor * deviceScaleFactor();
-
     // FIXME: catch zero-size height or width here (or earlier)?
-    return m_size.width() * effectiveScale > cMaxPixelDimension || m_size.height() * effectiveScale > cMaxPixelDimension;
+    return m_size.width() * pageScaleFactor > cMaxPixelDimension || m_size.height() * pageScaleFactor > cMaxPixelDimension;
 }
 
 void GraphicsLayerCA::swapFromOrToTiledLayer(bool useTiledLayer)
@@ -3010,8 +3008,7 @@
 void GraphicsLayerCA::computePixelAlignment(float pageScaleFactor, const FloatPoint& positionRelativeToBase,
     FloatPoint& position, FloatSize& size, FloatPoint3D& anchorPoint, FloatSize& alignmentOffset) const
 {
-    float effectiveScale = pageScaleFactor * deviceScaleFactor();
-    if (!m_maintainsPixelAlignment || isIntegral(effectiveScale) || !m_drawsContent || m_masksToBounds) {
+    if (!m_maintainsPixelAlignment || isIntegral(pageScaleFactor) || !m_drawsContent || m_masksToBounds) {
         position = m_position;
         size = m_size;
         anchorPoint = m_anchorPoint;
@@ -3022,12 +3019,12 @@
     FloatRect baseRelativeBounds(positionRelativeToBase, m_size);
     FloatRect scaledBounds = baseRelativeBounds;
     // Scale by the page scale factor to compute the screen-relative bounds.
-    scaledBounds.scale(effectiveScale);
+    scaledBounds.scale(pageScaleFactor);
     // Round to integer boundaries.
     FloatRect alignedBounds = enclosingIntRect(scaledBounds);
     
     // Convert back to layer coordinates.
-    alignedBounds.scale(1 / effectiveScale);
+    alignedBounds.scale(1 / pageScaleFactor);
     
     // Epsilon is necessary to ensure that backing store size computation in CA, which involves integer truncation,
     // will match our aligned bounds.