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PixelDumpSupport.cpp
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94 lines (81 loc) · 3.98 KB
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/*
* Copyright (C) 2009 Apple, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "PixelDumpSupport.h"
#include "CyclicRedundancyCheck.h"
#include <cstdio>
static void appendIntToVector(unsigned number, Vector<unsigned char>& vector)
{
size_t offset = vector.size();
vector.grow(offset + 4);
vector[offset] = ((number >> 24) & 0xff);
vector[offset + 1] = ((number >> 16) & 0xff);
vector[offset + 2] = ((number >> 8) & 0xff);
vector[offset + 3] = (number & 0xff);
}
static void convertChecksumToPNGComment(const char* checksum, Vector<unsigned char>& bytesToAdd)
{
// Chunks of PNG files are <length>, <type>, <data>, <crc>.
static const char textCommentPrefix[] = "\x00\x00\x00\x29tEXtchecksum\x00";
static const size_t prefixLength = sizeof(textCommentPrefix) - 1; // The -1 is for the null at the end of the char[].
static const size_t checksumLength = 32;
bytesToAdd.append(textCommentPrefix, prefixLength);
bytesToAdd.append(checksum, checksumLength);
Vector<unsigned char> dataToCrc;
dataToCrc.append(textCommentPrefix + 4, prefixLength - 4); // Don't include the chunk length in the crc.
dataToCrc.append(checksum, checksumLength);
unsigned crc32 = computeCrc(dataToCrc);
appendIntToVector(crc32, bytesToAdd);
}
static size_t offsetAfterIHDRChunk(const unsigned char* data, const size_t dataLength)
{
const int pngHeaderLength = 8;
const int pngIHDRChunkLength = 25; // chunk length + "IHDR" + 13 bytes of data + checksum
return pngHeaderLength + pngIHDRChunkLength;
}
void printPNG(const unsigned char* data, const size_t dataLength, const char* checksum)
{
Vector<unsigned char> bytesToAdd;
convertChecksumToPNGComment(checksum, bytesToAdd);
printf("Content-Type: %s\n", "image/png");
printf("Content-Length: %lu\n", static_cast<unsigned long>(dataLength + bytesToAdd.size()));
size_t insertOffset = offsetAfterIHDRChunk(data, dataLength);
fwrite(data, 1, insertOffset, stdout);
fwrite(bytesToAdd.data(), 1, bytesToAdd.size(), stdout);
const size_t bytesToWriteInOneChunk = 1 << 15;
data += insertOffset;
size_t dataRemainingToWrite = dataLength - insertOffset;
while (dataRemainingToWrite) {
size_t bytesToWriteInThisChunk = std::min(dataRemainingToWrite, bytesToWriteInOneChunk);
size_t bytesWritten = fwrite(data, 1, bytesToWriteInThisChunk, stdout);
if (bytesWritten != bytesToWriteInThisChunk)
break;
dataRemainingToWrite -= bytesWritten;
data += bytesWritten;
}
}