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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkPngEncoder_DEFINED
#define SkPngEncoder_DEFINED
#include "SkEncoder.h"
#include "SkDataTable.h"
class SkPngEncoderMgr;
class SkWStream;
class SK_API SkPngEncoder : public SkEncoder {
public:
enum class FilterFlag : int {
kZero = 0x00,
kNone = 0x08,
kSub = 0x10,
kUp = 0x20,
kAvg = 0x40,
kPaeth = 0x80,
kAll = kNone | kSub | kUp | kAvg | kPaeth,
};
struct Options {
/**
* Selects which filtering strategies to use.
*
* If a single filter is chosen, libpng will use that filter for every row.
*
* If multiple filters are chosen, libpng will use a heuristic to guess which filter
* will encode smallest, then apply that filter. This happens on a per row basis,
* different rows can use different filters.
*
* Using a single filter (or less filters) is typically faster. Trying all of the
* filters may help minimize the output file size.
*
* Our default value matches libpng's default.
*/
FilterFlag fFilterFlags = FilterFlag::kAll;
/**
* Must be in [0, 9] where 9 corresponds to maximal compression. This value is passed
* directly to zlib. 0 is a special case to skip zlib entirely, creating dramatically
* larger pngs.
*
* Our default value matches libpng's default.
*/
int fZLibLevel = 6;
/**
* Represents comments in the tEXt ancillary chunk of the png.
* The 2i-th entry is the keyword for the i-th comment,
* and the (2i + 1)-th entry is the text for the i-th comment.
*/
sk_sp<SkDataTable> fComments;
};
/**
* Encode the |src| pixels to the |dst| stream.
* |options| may be used to control the encoding behavior.
*
* Returns true on success. Returns false on an invalid or unsupported |src|.
*/
static bool Encode(SkWStream* dst, const SkPixmap& src, const Options& options);
/**
* Create a png encoder that will encode the |src| pixels to the |dst| stream.
* |options| may be used to control the encoding behavior.
*
* |dst| is unowned but must remain valid for the lifetime of the object.
*
* This returns nullptr on an invalid or unsupported |src|.
*/
static std::unique_ptr<SkEncoder> Make(SkWStream* dst, const SkPixmap& src,
const Options& options);
~SkPngEncoder() override;
protected:
bool onEncodeRows(int numRows) override;
SkPngEncoder(std::unique_ptr<SkPngEncoderMgr>, const SkPixmap& src);
std::unique_ptr<SkPngEncoderMgr> fEncoderMgr;
typedef SkEncoder INHERITED;
};
static inline SkPngEncoder::FilterFlag operator|(SkPngEncoder::FilterFlag x,
SkPngEncoder::FilterFlag y) {
return (SkPngEncoder::FilterFlag)((int)x | (int)y);
}
#endif
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