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// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Author: lode.vandevenne@gmail.com (Lode Vandevenne)
// Author: jyrki.alakuijala@gmail.com (Jyrki Alakuijala)
// Library to recompress and optimize PNG images. Uses Zopfli as the compression
// backend, chooses optimal PNG color model, and tries out several PNG filter
// strategies.
#ifndef ZOPFLIPNG_LIB_H_
#define ZOPFLIPNG_LIB_H_
#ifdef __cplusplus
#include <string>
#include <vector>
extern "C" {
#endif
#include <stdlib.h>
enum ZopfliPNGFilterStrategy {
kStrategyZero = 0,
kStrategyOne = 1,
kStrategyTwo = 2,
kStrategyThree = 3,
kStrategyFour = 4,
kStrategyMinSum,
kStrategyEntropy,
kStrategyPredefined,
kStrategyBruteForce,
kNumFilterStrategies /* Not a strategy but used for the size of this enum */
};
typedef struct CZopfliPNGOptions {
int lossy_transparent;
int lossy_8bit;
enum ZopfliPNGFilterStrategy* filter_strategies;
// How many strategies to try.
int num_filter_strategies;
int auto_filter_strategy;
char** keepchunks;
// How many entries in keepchunks.
int num_keepchunks;
int use_zopfli;
int num_iterations;
int num_iterations_large;
int block_split_strategy;
} CZopfliPNGOptions;
// Sets the default options
// Does not allocate or set keepchunks or filter_strategies
void CZopfliPNGSetDefaults(CZopfliPNGOptions *png_options);
// Returns 0 on success, error code otherwise
// The caller must free resultpng after use
int CZopfliPNGOptimize(const unsigned char* origpng,
const size_t origpng_size,
const CZopfliPNGOptions* png_options,
int verbose,
unsigned char** resultpng,
size_t* resultpng_size);
#ifdef __cplusplus
} // extern "C"
#endif
// C++ API
#ifdef __cplusplus
struct ZopfliPNGOptions {
ZopfliPNGOptions();
bool verbose;
// Allow altering hidden colors of fully transparent pixels
bool lossy_transparent;
// Convert 16-bit per channel images to 8-bit per channel
bool lossy_8bit;
// Filter strategies to try
std::vector<ZopfliPNGFilterStrategy> filter_strategies;
// Automatically choose filter strategy using less good compression
bool auto_filter_strategy;
// Keep original color type (RGB, RGBA, gray, gray+alpha or palette) and bit
// depth of the PNG.
// This results in a loss of compression opportunities, e.g. it will no
// longer convert a 4-channel RGBA image to 2-channel gray+alpha if the image
// only had translucent gray pixels.
// May be useful if a device does not support decoding PNGs of a particular
// color type.
// Default value: false.
bool keep_colortype;
// PNG chunks to keep
// chunks to literally copy over from the original PNG to the resulting one
std::vector<std::string> keepchunks;
// Use Zopfli deflate compression
bool use_zopfli;
// Zopfli number of iterations
int num_iterations;
// Zopfli number of iterations on large images
int num_iterations_large;
// Unused, left for backwards compatiblity.
int block_split_strategy;
};
// Returns 0 on success, error code otherwise.
// If verbose is true, it will print some info while working.
int ZopfliPNGOptimize(const std::vector<unsigned char>& origpng,
const ZopfliPNGOptions& png_options,
bool verbose,
std::vector<unsigned char>* resultpng);
#endif // __cplusplus
#endif // ZOPFLIPNG_LIB_H_
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