Use LCD text if the transform IsAlmostIdentityAndIntegerTranslation

cc/layer_tree_host_common.cc

Index: cc/layer_tree_host_common.cc
diff --git a/cc/layer_tree_host_common.cc b/cc/layer_tree_host_common.cc
index c28db4087d3f31f8d5c671f1042c957d8e43b441..f7c38a0a2563c78eaa53349f6632dad5b4e2bd34 100644
--- a/cc/layer_tree_host_common.cc
+++ b/cc/layer_tree_host_common.cc
@@ -731,7 +731,7 @@ static void calculateDrawPropertiesInternal(LayerType* layer, const gfx::Transfo
     // To avoid color fringing, LCD text should only be used on opaque layers with just integral translation.
     bool layerCanUseLCDText = subtreeCanUseLCDText &&
                               (accumulatedDrawOpacity == 1.0) &&
-                              layerDrawProperties.target_space_transform.IsIdentityOrIntegerTranslation();
+                              layerDrawProperties.target_space_transform.IsAlmostIdentityOrIntegerTranslation();

[enne (OOO), 2013/03/07 21:52:15]

I think it's fine to do the check here, but then I think you also need to round
the combinedTransform if this is true, otherwise you'll get noticeable fringing
as the text is stretched ever-so-slightly.

[Xianzhu, 2013/03/07 21:55:36]

I have no idea how to round combinedTransform because normally there aren't
"almost integers" in it. Compensating the errors back into it may cause more
errors.

 
     gfx::RectF contentRect(gfx::PointF(), layer->contentBounds());