Create SkBitmapChecksummer and associated SkBitmapTransformer
As needed to start capturing gm image checksums.
Review URL: https://codereview.appspot.com/6920050
git-svn-id: http://skia.googlecode.com/svn/trunk@6759 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/utils/SkBitmapChecksummer.h b/src/utils/SkBitmapChecksummer.h
new file mode 100644
index 0000000..63ac726
--- /dev/null
+++ b/src/utils/SkBitmapChecksummer.h
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+
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkBitmapChecksummer_DEFINED
+#define SkBitmapChecksummer_DEFINED
+
+#include "SkBitmap.h"
+#include "SkBitmapTransformer.h"
+
+/**
+ * Static class that can generate checksums from SkBitmaps.
+ */
+class SkBitmapChecksummer {
+public:
+ /**
+ * Returns a 64-bit checksum of the pixels in this bitmap.
+ *
+ * If this is unable to compute the checksum for some reason,
+ * it returns 0.
+ *
+ * Note: depending on the bitmap config, we may need to create an
+ * intermediate SkBitmap and copy the pixels over to it... so in some
+ * cases, performance and memory usage can suffer.
+ */
+ static uint64_t Compute64(const SkBitmap& bitmap);
+
+private:
+ static uint64_t Compute64Internal(const SkBitmap& bitmap,
+ const SkBitmapTransformer& transformer);
+};
+
+#endif