Account for colorfilter transparency in determining paint opacity

bug:17765601
Change-Id: I90d76ee199bb357c71fc8f537c1abfa20d848416
diff --git a/libs/hwui/Renderer.h b/libs/hwui/Renderer.h
index 9cedd5a..a2f8c05 100644
--- a/libs/hwui/Renderer.h
+++ b/libs/hwui/Renderer.h
@@ -17,12 +17,13 @@
 #ifndef ANDROID_HWUI_RENDERER_H
 #define ANDROID_HWUI_RENDERER_H
 
+#include <SkColorFilter.h>
+#include <SkPaint.h>
 #include <SkRegion.h>
 
 #include <utils/String8.h>
 
 #include "AssetAtlas.h"
-#include "SkPaint.h"
 
 namespace android {
 
@@ -81,6 +82,14 @@
                 && !paint.getColorFilter()
                 && getXfermode(paint.getXfermode()) == SkXfermode::kSrcOver_Mode;
     }
+
+    static bool isBlendedColorFilter(const SkColorFilter* filter) {
+        if (filter == NULL) {
+            return false;
+        }
+        return (filter->getFlags() & SkColorFilter::kAlphaUnchanged_Flag) == 0;
+    }
+
 // ----------------------------------------------------------------------------
 // Frame state operations
 // ----------------------------------------------------------------------------