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28978c4f66
Later in the patch series, we use the new APIs to facilitate cloning of an existing decoder. This is useful when you want to redecode the same image with the exact same configuration but from the very beginning.
70 lines
2.1 KiB
C++
70 lines
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_image_decoders_nsIconDecoder_h
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#define mozilla_image_decoders_nsIconDecoder_h
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#include "Decoder.h"
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#include "StreamingLexer.h"
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#include "SurfacePipe.h"
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namespace mozilla {
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namespace image {
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class RasterImage;
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////////////////////////////////////////////////////////////////////////////////
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// The icon decoder is a decoder specifically tailored for loading icons
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// from the OS. We've defined our own little format to represent these icons
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// and this decoder takes that format and converts it into 24-bit RGB with
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// alpha channel support. It was modeled a bit off the PPM decoder.
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//
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// The format of the incoming data is as follows:
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//
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// The first two bytes contain the width and the height of the icon.
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// The remaining bytes contain the icon data, 4 bytes per pixel, in
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// ARGB order (platform endianness, A in highest bits, B in lowest
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// bits), row-primary, top-to-bottom, left-to-right, with
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// premultiplied alpha.
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//
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////////////////////////////////////////////////////////////////////////////////
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class nsIconDecoder : public Decoder
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{
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public:
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virtual ~nsIconDecoder();
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DecoderType GetType() const override { return DecoderType::ICON; }
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LexerResult DoDecode(SourceBufferIterator& aIterator,
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IResumable* aOnResume) override;
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private:
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friend class DecoderFactory;
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// Decoders should only be instantiated via DecoderFactory.
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explicit nsIconDecoder(RasterImage* aImage);
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enum class State {
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HEADER,
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ROW_OF_PIXELS,
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FINISH
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};
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LexerTransition<State> ReadHeader(const char* aData);
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LexerTransition<State> ReadRowOfPixels(const char* aData, size_t aLength);
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LexerTransition<State> Finish();
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StreamingLexer<State> mLexer;
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SurfacePipe mPipe;
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uint32_t mBytesPerRow;
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};
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} // namespace image
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} // namespace mozilla
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#endif // mozilla_image_decoders_nsIconDecoder_h
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