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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkBmpCodec_DEFINED
#define SkBmpCodec_DEFINED
#include "SkCodec.h"
#include "SkColorSpace.h"
#include "SkColorTable.h"
#include "SkImageInfo.h"
#include "SkStream.h"
#include "SkSwizzler.h"
#include "SkTypes.h"
/*
* This class enables code sharing between its bmp codec subclasses. The
* subclasses actually do the work.
*/
class SkBmpCodec : public SkCodec {
public:
static bool IsBmp(const void*, size_t);
/*
* Assumes IsBmp was called and returned true
* Creates a bmp decoder
* Reads enough of the stream to determine the image format
*/
static SkCodec* NewFromStream(SkStream*);
/*
* Creates a bmp decoder for a bmp embedded in ico
* Reads enough of the stream to determine the image format
*/
static SkCodec* NewFromIco(SkStream*);
protected:
SkBmpCodec(int width, int height, const SkEncodedInfo& info, SkStream* stream,
uint16_t bitsPerPixel, SkCodec::SkScanlineOrder rowOrder);
SkEncodedFormat onGetEncodedFormat() const override { return kBMP_SkEncodedFormat; }
/*
* Read enough of the stream to initialize the SkBmpCodec. Returns a bool
* representing success or failure. If it returned true, and codecOut was
* not nullptr, it will be set to a new SkBmpCodec.
* Does *not* take ownership of the passed in SkStream.
*/
static bool ReadHeader(SkStream*, bool inIco, SkCodec** codecOut);
bool onRewind() override;
/*
* Returns whether this BMP is part of an ICO image.
*/
bool inIco() const {
return this->onInIco();
}
virtual bool onInIco() const {
return false;
}
/*
* Get the destination row number corresponding to the encoded row number.
* For kTopDown, we simply return y, but for kBottomUp, the rows will be
* decoded in reverse order.
*
* @param y Iterates from 0 to height, indicating the current row.
* @param height The height of the current subset of the image that we are
* decoding. This is generally equal to the full height
* when we want to decode the full or one when we are
* sampling.
*/
int32_t getDstRow(int32_t y, int32_t height) const;
/*
* Accessors used by subclasses
*/
uint16_t bitsPerPixel() const { return fBitsPerPixel; }
SkScanlineOrder onGetScanlineOrder() const override { return fRowOrder; }
size_t srcRowBytes() const { return fSrcRowBytes; }
/*
* To be overriden by bmp subclasses, which provide unique implementations.
* Performs subclass specific setup.
*
* @param dstInfo Contains output information. Height specifies
* the total number of rows that will be decoded.
* @param options Additonal options to pass to the decoder.
* @param inputColorPtr Client-provided memory for a color table. Must
* be enough for 256 colors. This will be
* populated with colors if the encoded image uses
* a color table.
* @param inputColorCount If the encoded image uses a color table, this
* will be set to the number of colors in the
* color table.
*/
virtual SkCodec::Result prepareToDecode(const SkImageInfo& dstInfo,
const SkCodec::Options& options, SkPMColor inputColorPtr[],
int* inputColorCount) = 0;
private:
/*
* Creates a bmp decoder
* Reads enough of the stream to determine the image format
*/
static SkCodec* NewFromStream(SkStream*, bool inIco);
/*
* Decodes the next dstInfo.height() lines.
*
* onGetPixels() uses this for full image decodes.
* SkScaledCodec::onGetPixels() uses the scanline decoder to call this with
* dstInfo.height() = 1, in order to implement sampling.
* A potential future use is to allow the caller to decode a subset of the
* lines in the image.
*
* @param dstInfo Contains output information. Height specifies the
* number of rows to decode at this time.
* @param dst Memory location to store output pixels
* @param dstRowBytes Bytes in a row of the destination
* @return Number of rows successfully decoded
*/
virtual int decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
const Options& opts) = 0;
virtual bool skipRows(int count);
Result onStartScanlineDecode(const SkImageInfo& dstInfo, const SkCodec::Options&,
SkPMColor inputColorPtr[], int* inputColorCount) override;
int onGetScanlines(void* dst, int count, size_t rowBytes) override;
bool onSkipScanlines(int count) override;
const uint16_t fBitsPerPixel;
const SkScanlineOrder fRowOrder;
const size_t fSrcRowBytes;
typedef SkCodec INHERITED;
};
#endif
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