Add SkPaint::getHash().

include/core/SkPaint.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPaint_DEFINED
 #define SkPaint_DEFINED
 
@@ skipping 44 matching lines @@
 
     /** operator== may give false negatives: two paints that draw equivalently
         may return false.  It will never give false positives: two paints that
         are not equivalent always return false.
     */
     SK_API friend bool operator==(const SkPaint& a, const SkPaint& b);
     friend bool operator!=(const SkPaint& a, const SkPaint& b) {
         return !(a == b);
     }
 
+    /** getHash() is a shallow hash, with the same limitations as operator==.
+     *  If operator== returns true for two paints, getHash() returns the same value for each.
+     */
+    uint32_t getHash() const;
+
     void flatten(SkWriteBuffer&) const;
     void unflatten(SkReadBuffer&);
 
     /** Restores the paint to its initial settings.
     */
     void reset();
 
     /** Specifies the level of hinting to be performed. These names are taken
         from the Gnome/Cairo names for the same. They are translated into
         Freetype concepts the same as in cairo-ft-font.c:
@@ skipping 1031 matching lines @@
     friend class SkCanonicalizePaint;
 
 #ifdef SK_BUILD_FOR_ANDROID
     // In order for the == operator to work properly this must be the last field
     // in the struct so that we can do a memcmp to this field's offset.
     uint32_t        fGenerationID;
 #endif
 };
 
 #endif