/*
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* Copyright 2015 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 SkBmpCodec_DEFINED
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#define SkBmpCodec_DEFINED
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#include "SkCodec.h"
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#include "SkColorSpace.h"
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#include "SkColorTable.h"
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#include "SkImageInfo.h"
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#include "SkStream.h"
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#include "SkSwizzler.h"
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#include "SkTypes.h"
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/*
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* This class enables code sharing between its bmp codec subclasses. The
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* subclasses actually do the work.
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*/
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class SkBmpCodec : public SkCodec {
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public:
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static bool IsBmp(const void*, size_t);
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/*
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* Assumes IsBmp was called and returned true
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* Creates a bmp decoder
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* Reads enough of the stream to determine the image format
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*/
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static std::unique_ptr<SkCodec> MakeFromStream(std::unique_ptr<SkStream>, Result*);
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/*
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* Creates a bmp decoder for a bmp embedded in ico
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* Reads enough of the stream to determine the image format
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*/
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static std::unique_ptr<SkCodec> MakeFromIco(std::unique_ptr<SkStream>, Result*);
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protected:
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SkBmpCodec(SkEncodedInfo&& info, std::unique_ptr<SkStream>,
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uint16_t bitsPerPixel, SkCodec::SkScanlineOrder rowOrder);
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SkEncodedImageFormat onGetEncodedFormat() const override { return SkEncodedImageFormat::kBMP; }
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/*
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* Read enough of the stream to initialize the SkBmpCodec.
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* On kSuccess, if codecOut is not nullptr, it will be set to a new SkBmpCodec.
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*/
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static Result ReadHeader(SkStream*, bool inIco, std::unique_ptr<SkCodec>* codecOut);
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bool onRewind() override;
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/*
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* Returns whether this BMP is part of an ICO image.
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*/
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bool inIco() const {
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return this->onInIco();
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}
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virtual bool onInIco() const {
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return false;
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}
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/*
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* Get the destination row number corresponding to the encoded row number.
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* For kTopDown, we simply return y, but for kBottomUp, the rows will be
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* decoded in reverse order.
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*
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* @param y Iterates from 0 to height, indicating the current row.
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* @param height The height of the current subset of the image that we are
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* decoding. This is generally equal to the full height
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* when we want to decode the full or one when we are
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* sampling.
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*/
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int32_t getDstRow(int32_t y, int32_t height) const;
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/*
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* Accessors used by subclasses
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*/
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uint16_t bitsPerPixel() const { return fBitsPerPixel; }
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SkScanlineOrder onGetScanlineOrder() const override { return fRowOrder; }
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size_t srcRowBytes() const { return fSrcRowBytes; }
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/*
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* To be overriden by bmp subclasses, which provide unique implementations.
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* Performs subclass specific setup.
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*
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* @param dstInfo Contains output information. Height specifies
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* the total number of rows that will be decoded.
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* @param options Additonal options to pass to the decoder.
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*/
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virtual SkCodec::Result onPrepareToDecode(const SkImageInfo& dstInfo,
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const SkCodec::Options& options) = 0;
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SkCodec::Result prepareToDecode(const SkImageInfo& dstInfo,
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const SkCodec::Options& options);
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uint32_t* xformBuffer() const { return fXformBuffer.get(); }
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void resetXformBuffer(int count) { fXformBuffer.reset(new uint32_t[count]); }
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/*
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* BMPs are typically encoded as BGRA/BGR so this is a more efficient choice
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* than RGBA.
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*/
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static constexpr SkColorType kXformSrcColorType = kBGRA_8888_SkColorType;
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static constexpr auto kXformSrcColorFormat = skcms_PixelFormat_BGRA_8888;
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private:
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/*
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* Creates a bmp decoder
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* Reads enough of the stream to determine the image format
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*/
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static std::unique_ptr<SkCodec> MakeFromStream(std::unique_ptr<SkStream>, Result*, bool inIco);
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/*
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* Decodes the next dstInfo.height() lines.
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*
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* onGetPixels() uses this for full image decodes.
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* SkScaledCodec::onGetPixels() uses the scanline decoder to call this with
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* dstInfo.height() = 1, in order to implement sampling.
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* A potential future use is to allow the caller to decode a subset of the
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* lines in the image.
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*
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* @param dstInfo Contains output information. Height specifies the
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* number of rows to decode at this time.
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* @param dst Memory location to store output pixels
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* @param dstRowBytes Bytes in a row of the destination
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* @return Number of rows successfully decoded
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*/
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virtual int decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
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const Options& opts) = 0;
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virtual bool skipRows(int count);
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Result onStartScanlineDecode(const SkImageInfo& dstInfo,
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const SkCodec::Options&) override;
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int onGetScanlines(void* dst, int count, size_t rowBytes) override;
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bool onSkipScanlines(int count) override;
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const uint16_t fBitsPerPixel;
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const SkScanlineOrder fRowOrder;
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const size_t fSrcRowBytes;
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std::unique_ptr<uint32_t[]> fXformBuffer;
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typedef SkCodec INHERITED;
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};
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#endif
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