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