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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.
*/
#include "SkBitmap.h"
#include "SkBitmapChecksummer.h"
#include "SkBitmapTransformer.h"
#include "SkCityHash.h"
#include "SkEndian.h"
/**
* Write an integer value into a bytebuffer in little-endian order.
*/
static void write_int_to_buffer(int val, char* buf) {
val = SkEndian_SwapLE32(val);
for (int byte=0; byte<4; byte++) {
*buf++ = (char)(val & 0xff);
val = val >> 8;
}
}
/*static*/ uint64_t SkBitmapChecksummer::Compute64Internal(
const SkBitmap& bitmap, const SkBitmapTransformer& transformer) {
size_t pixelBufferSize = transformer.bytesNeededTotal();
size_t totalBufferSize = pixelBufferSize + 8; // leave room for x/y dimensions
SkAutoMalloc bufferManager(totalBufferSize);
char *bufferStart = static_cast<char *>(bufferManager.get());
char *bufPtr = bufferStart;
// start with the x/y dimensions
write_int_to_buffer(bitmap.width(), bufPtr);
bufPtr += 4;
write_int_to_buffer(bitmap.height(), bufPtr);
bufPtr += 4;
// add all the pixel data
if (!transformer.copyBitmapToPixelBuffer(bufPtr, pixelBufferSize)) {
return 0;
}
return SkCityHash::Compute64(bufferStart, totalBufferSize);
}
/*static*/ uint64_t SkBitmapChecksummer::Compute64(const SkBitmap& bitmap) {
const SkBitmapTransformer::PixelFormat kPixelFormat =
SkBitmapTransformer::kARGB_8888_Premul_PixelFormat;
// First, try to transform the existing bitmap.
const SkBitmapTransformer transformer =
SkBitmapTransformer(bitmap, kPixelFormat);
if (transformer.isValid(false)) {
return Compute64Internal(bitmap, transformer);
}
// Hmm, that didn't work. Maybe if we create a new
// kARGB_8888_Config version of the bitmap it will work better?
SkBitmap copyBitmap;
bitmap.copyTo(©Bitmap, SkBitmap::kARGB_8888_Config);
const SkBitmapTransformer copyTransformer =
SkBitmapTransformer(copyBitmap, kPixelFormat);
if (copyTransformer.isValid(true)) {
return Compute64Internal(copyBitmap, copyTransformer);
} else {
return 0;
}
}
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