More genericity: overload isPaintOpaque(SkPaint, SkBitmap)

src/core/SkPaintPriv.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPaintPriv_DEFINED
 #define SkPaintPriv_DEFINED
 
 class SkBitmap;
 class SkPaint;
 
 #include "SkTypes.h"
+
+enum SkPaintBitmapOpacity {
+    // No content replaces the paint's color
+    kNoBitmap_SkPaintBitmapOpacity = 0,
+    // The color replacement is known to be opaque
+    kOpaque_SkPaintBitmapOpacity = 1,
+    // We have no information about the color or it is transparent
+    kUnknown_SkPaintBitmapOpacity = 2
+};
+
 /** Returns true if draw calls that use the paint will completely occlude
     canvas contents that are covered by the draw.
     @param paint The paint to be analyzed, NULL is equivalent to
+        the default paint.
+    @param contentType The type of the content that will be drawn,
+        kNoBitmap_SkPaintBitmapOpacity if there is no content in adition to the paint.
+    @return true if paint is opaque
+*/
+bool isPaintOpaque(const SkPaint* paint, SkPaintBitmapOpacity contentType);
+
+/** Returns true if draw calls that use the paint will completely occlude
+    canvas contents that are covered by the draw.
+    @param paint The paint to be analyzed, NULL is equivalent to
         the default paint.
     @param bmpReplacesShader a bitmap to be used in place of the paint's
         shader.
     @return true if paint is opaque
 */
 bool isPaintOpaque(const SkPaint* paint,
                    const SkBitmap* bmpReplacesShader = NULL);
 #endif