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/*
* Copyright (c) 2010, Google 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:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Google Inc. 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT
* OWNER OR 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 "platform/image-encoders/PNGImageEncoder.h"
#include "platform/graphics/ImageBuffer.h"
#include "wtf/PtrUtil.h"
#include <memory>
#include "zlib.h"
namespace blink {
PNGImageEncoderState::~PNGImageEncoderState() {
png_destroy_write_struct(&m_png, &m_info);
}
static void writeOutput(png_structp png, png_bytep data, png_size_t size) {
static_cast<Vector<unsigned char>*>(png_get_io_ptr(png))->append(data, size);
}
std::unique_ptr<PNGImageEncoderState> PNGImageEncoderState::create(
const IntSize& imageSize,
Vector<unsigned char>* output) {
if (imageSize.width() <= 0 || imageSize.height() <= 0)
return nullptr;
png_struct* png = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
png_info* info = png_create_info_struct(png);
if (!png || !info || setjmp(png_jmpbuf(png))) {
png_destroy_write_struct(png ? &png : 0, info ? &info : 0);
return nullptr;
}
// Optimize compression for speed.
// The parameters are the same as what libpng uses by default for RGB and RGBA
// images, except:
// The zlib compression level is set to 3 instead of 6, to avoid the lazy
// Ziv-Lempel match searching.
png_set_compression_level(png, 3);
// The zlib memory level is set to 8. This actually matches the default, we
// are just future-proofing.
png_set_compression_mem_level(png, 8);
// The zlib strategy is set to Z_FILTERED, which does not match the default.
// Avoid the zlib strategies Z_HUFFMAN_ONLY or Z_RLE.
// Although they are the fastest for poorly-compressible images (e.g.
// photographs), they are very slow for highly-compressible images (e.g. text,
// drawings or business graphics)
png_set_compression_strategy(png, Z_FILTERED);
// The delta filter is PNG_FILTER_SUB instead of PNG_ALL_FILTERS, to reduce
// the filter computations.
png_set_filter(png, PNG_FILTER_TYPE_BASE, PNG_FILTER_SUB);
png_set_write_fn(png, output, writeOutput, 0);
png_set_IHDR(png, info, imageSize.width(), imageSize.height(), 8,
PNG_COLOR_TYPE_RGB_ALPHA, 0, 0, 0);
png_write_info(png, info);
return WTF::wrapUnique(new PNGImageEncoderState(png, info));
}
void PNGImageEncoder::writeOneRowToPng(unsigned char* pixels,
PNGImageEncoderState* encoderState) {
png_write_row(encoderState->png(), pixels);
}
void PNGImageEncoder::finalizePng(PNGImageEncoderState* encoderState) {
png_write_end(encoderState->png(), encoderState->info());
}
static bool encodePixels(const IntSize& imageSize,
const unsigned char* inputPixels,
Vector<unsigned char>* output) {
std::unique_ptr<PNGImageEncoderState> encoderState =
PNGImageEncoderState::create(imageSize, output);
if (!encoderState.get())
return false;
unsigned char* pixels = const_cast<unsigned char*>(inputPixels);
const size_t pixelRowStride = imageSize.width() * 4;
for (int y = 0; y < imageSize.height(); ++y) {
PNGImageEncoder::writeOneRowToPng(pixels, encoderState.get());
pixels += pixelRowStride;
}
PNGImageEncoder::finalizePng(encoderState.get());
return true;
}
bool PNGImageEncoder::encode(const ImageDataBuffer& imageData,
Vector<unsigned char>* output) {
if (!imageData.pixels())
return false;
return encodePixels(imageData.size(), imageData.pixels(), output);
}
} // namespace blink
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