rename utility to see if a paint will overwrite its pixels

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
 
 #include "SkTypes.h"
 
 class SkBitmap;
 class SkImage;
 class SkPaint;
 
-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
+class SkPaintPriv {
+public:
+    /**
+     *  Returns true if drawing with this paint (or NULL) will ovewrite all affected pixels.
+     *
+     *  Note: returns conservative true, meaning it may return false even though the paint might
+     *        in fact overwrite its pixels.
+     */
+    static bool Overwrites(const SkPaint& paint);
+
+    /**
+     *  Returns true if drawing this bitmap with this paint (or NULL) will ovewrite all affected
+     *  pixels.
+     */
+    static bool Overwrites(const SkBitmap&, const SkPaint* paint);
+
+    /**
+     *  Returns true if drawing this image with this paint (or NULL) will ovewrite all affected
+     *  pixels.
+     */
+    static bool Overwrites(const SkImage*, const SkPaint* paint);
 };
 
-/** 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);
-bool isPaintOpaque(const SkPaint* paint, const SkImage* image);
-
 #endif