Add SkPaint::getHash().

src/core/SkPaint.cpp

 /*
  * 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.
  */
 
 #include "SkPaint.h"
 #include "SkAnnotation.h"
 #include "SkAutoKern.h"
+#include "SkChecksum.h"
 #include "SkColorFilter.h"
 #include "SkData.h"
 #include "SkDeviceProperties.h"
 #include "SkDraw.h"
 #include "SkFontDescriptor.h"
 #include "SkFontHost.h"
 #include "SkGlyphCache.h"
 #include "SkImageFilter.h"
 #include "SkMaskFilter.h"
 #include "SkMaskGamma.h"
@@ skipping 2432 matching lines @@
                 return 0 == this->getAlpha();
             case SkXfermode::kDst_Mode:
                 return true;
             default:
                 break;
         }
     }
     return false;
 }
 
+uint32_t SkPaint::getHash() const {
+    // We're going to hash 10 pointers and 7 32-bit values, finishing up with fBitfields,
+    // so fBitfields should be 10 pointers and 6 32-bit values from the start.
+    SK_COMPILE_ASSERT(offsetof(SkPaint, fBitfields) == 10 * sizeof(void*) + 6 * sizeof(uint32_t),
+                      SkPaint_notPackedTightly);
+    return SkChecksum::Murmur3(reinterpret_cast<const uint32_t*>(this),
+                               offsetof(SkPaint, fBitfields) + sizeof(fBitfields));
+}