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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 SkSwizzler_DEFINED
#define SkSwizzler_DEFINED
#include "SkCodec.h"
#include "SkColor.h"
#include "SkImageInfo.h"
class SkSwizzler : public SkNoncopyable {
public:
/**
* Enum describing the config of the source data.
*/
enum SrcConfig {
kUnknown, // Invalid type.
kGray,
kIndex1,
kIndex2,
kIndex4,
kIndex,
kRGB,
kBGR,
kRGBX,
kBGRX,
kRGBA,
kBGRA,
kRGB_565,
};
/*
*
* Result code for the alpha components of a row.
*
*/
typedef uint16_t ResultAlpha;
static const ResultAlpha kOpaque_ResultAlpha = 0xFFFF;
static const ResultAlpha kTransparent_ResultAlpha = 0x0000;
/*
*
* Checks if the result of decoding a row indicates that the row was
* transparent.
*
*/
static bool IsTransparent(ResultAlpha r) {
return kTransparent_ResultAlpha == r;
}
/*
*
* Checks if the result of decoding a row indicates that the row was
* opaque.
*
*/
static bool IsOpaque(ResultAlpha r) {
return kOpaque_ResultAlpha == r;
}
/*
*
* Constructs the proper result code based on accumulated alpha masks
*
*/
static ResultAlpha GetResult(uint8_t zeroAlpha, uint8_t maxAlpha);
/*
*
* Returns bits per pixel for source config
*
*/
static int BitsPerPixel(SrcConfig sc) {
switch (sc) {
case kIndex1:
return 1;
case kIndex2:
return 2;
case kIndex4:
return 4;
case kGray:
case kIndex:
return 8;
case kRGB_565:
return 16;
case kRGB:
case kBGR:
return 24;
case kRGBX:
case kRGBA:
case kBGRX:
case kBGRA:
return 32;
default:
SkASSERT(false);
return 0;
}
}
/*
*
* Returns bytes per pixel for source config
* Raises an error if each pixel is not stored in an even number of bytes
*
*/
static int BytesPerPixel(SrcConfig sc) {
SkASSERT(SkIsAlign8(BitsPerPixel(sc)));
return BitsPerPixel(sc) >> 3;
}
/**
* Create a new SkSwizzler.
* @param SrcConfig Description of the format of the source.
* @param SkImageInfo dimensions() describe both the src and the dst.
* Other fields describe the dst.
* @param dst Destination to write pixels. Must match info and dstRowBytes
* @param dstRowBytes rowBytes for dst.
* @param ZeroInitialized Whether dst is zero-initialized. The
implementation may choose to skip writing zeroes
* if set to kYes_ZeroInitialized.
* @return A new SkSwizzler or NULL on failure.
*/
static SkSwizzler* CreateSwizzler(SrcConfig, const SkPMColor* ctable,
const SkImageInfo&, void* dst,
size_t dstRowBytes,
SkImageGenerator::ZeroInitialized);
/**
* Swizzle the next line. Call height times, once for each row of source.
* @param src The next row of the source data.
* @return A result code describing if the row was fully opaque, fully
* transparent, or neither
*/
ResultAlpha next(const uint8_t* SK_RESTRICT src);
/**
*
* Alternate version of next that allows the caller to specify the row.
* It is very important to only use one version of next. Since the other
* version modifies the dst pointer, it will change the behavior of this
* function. We will check this in Debug mode.
*
*/
ResultAlpha next(const uint8_t* SK_RESTRICT src, int y);
/**
* Update the destination row.
*
* Typically this is done by next, but for a client that wants to manually
* modify the destination row (for example, for decoding scanline one at a
* time) they can call this before each call to next.
* TODO: Maybe replace this with a version of next which allows supplying the
* destination?
*/
void setDstRow(void* dst) { fDstRow = dst; }
private:
#ifdef SK_DEBUG
/*
*
* Keep track of which version of next the caller is using
*
*/
enum NextMode {
kUninitialized_NextMode,
kConsecutive_NextMode,
kDesignateRow_NextMode,
};
NextMode fNextMode;
#endif
/**
* Method for converting raw data to Skia pixels.
* @param dstRow Row in which to write the resulting pixels.
* @param src Row of src data, in format specified by SrcConfig
* @param width Width in pixels
* @param deltaSrc if bitsPerPixel % 8 == 0, deltaSrc is bytesPerPixel
* else, deltaSrc is bitsPerPixel
* @param y Line of source.
* @param ctable Colors (used for kIndex source).
*/
typedef ResultAlpha (*RowProc)(void* SK_RESTRICT dstRow,
const uint8_t* SK_RESTRICT src,
int width, int deltaSrc, int y,
const SkPMColor ctable[]);
const RowProc fRowProc;
const SkPMColor* fColorTable; // Unowned pointer
const int fDeltaSrc; // if bitsPerPixel % 8 == 0
// deltaSrc is bytesPerPixel
// else
// deltaSrc is bitsPerPixel
const SkImageInfo fDstInfo;
void* fDstRow;
const size_t fDstRowBytes;
int fCurrY;
SkSwizzler(RowProc proc, const SkPMColor* ctable, int deltaSrc,
const SkImageInfo& info, void* dst, size_t rowBytes);
};
#endif // SkSwizzler_DEFINED
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