SkA8_Blitter Class Reference

Inheritance diagram for SkA8_Blitter:

Public Member Functions
	SkA8_Blitter (const SkPixmap &device, const SkPaint &paint)
void	blitH (int x, int y, int width) override
	Blit a horizontal run of one or more pixels.
void	blitAntiH (int x, int y, const SkAlpha antialias[], const int16_t runs[]) override
void	blitV (int x, int y, int height, SkAlpha alpha) override
	Blit a vertical run of pixels with a constant alpha value.
void	blitRect (int x, int y, int width, int height) override
	Blit a solid rectangle one or more pixels wide.
void	blitMask (const SkMask &, const SkIRect &) override
Public Member Functions inherited from SkBlitter
virtual	~SkBlitter ()
virtual void	blitAntiRect (int x, int y, int width, int height, SkAlpha leftAlpha, SkAlpha rightAlpha)
void	blitFatAntiRect (const SkRect &rect)
virtual void	blitAntiH2 (int x, int y, U8CPU a0, U8CPU a1)
virtual void	blitAntiV2 (int x, int y, U8CPU a0, U8CPU a1)
virtual bool	isNullBlitter () const
virtual int	requestRowsPreserved () const
virtual void *	allocBlitMemory (size_t sz)
void	blitRectRegion (const SkIRect &rect, const SkRegion &clip)
void	blitRegion (const SkRegion &clip)

Additional Inherited Members
Static Public Member Functions inherited from SkBlitter
static bool	UseLegacyBlitter (const SkPixmap &, const SkPaint &, const SkMatrix &)
static SkBlitter *	Choose (const SkPixmap &dst, const SkMatrix &ctm, const SkPaint &paint, SkArenaAlloc *, bool drawCoverage, sk_sp< SkShader > clipShader, const SkSurfaceProps &props)
static SkBlitter *	ChooseSprite (const SkPixmap &dst, const SkPaint &, const SkPixmap &src, int left, int top, SkArenaAlloc *, sk_sp< SkShader > clipShader)
Protected Attributes inherited from SkBlitter
SkAutoMalloc	fBlitMemory

Detailed Description

Definition at line 168 of file SkBlitter_A8.cpp.

Constructor & Destructor Documentation

SkA8_Blitter()

SkA8_Blitter::SkA8_Blitter	(	const SkPixmap &	device,
		const SkPaint &	paint
	)

Definition at line 187 of file SkBlitter_A8.cpp.

                                                 : fDevice(device) {
    SkASSERT(nullptr == paint.getShader());
    SkASSERT(nullptr == paint.getColorFilter());
    auto mode = paint.asBlendMode();
    SkASSERT(mode);
    auto pair = find_a8_rowproc_pair(*mode);
    SkASSERT(pair);
 
    fOneProc = pair->oneProc;
    fBWProc  = pair->bwProc;
    fAAProc  = pair->aaProc;
    fSrc = paint.getAlpha();
}

Member Function Documentation

blitAntiH()

void SkA8_Blitter::blitAntiH ( int  x, int  y, const SkAlpha  antialias[], const int16_t  runs[]  )

overridevirtual

Blit a horizontal run of antialiased pixels; runs[] is a sparse zero-terminated run-length encoding of spans of constant alpha values. The runs[] and antialias[] work together to represent long runs of pixels with the same alphas. The runs[] contains the number of pixels with the same alpha, and antialias[] contain the coverage value for that number of pixels. The runs[] (and antialias[]) are encoded in a clever way. The runs array is zero terminated, and has enough entries for each pixel plus one, in most cases some of the entries will not contain valid data. An entry in the runs array contains the number of pixels (np) that have the same alpha value. The next np value is found np entries away. For example, if runs[0] = 7, then the next valid entry will by at runs[7]. The runs array and antialias[] are coupled by index. So, if the np entry is at runs[45] = 12 then the alpha value can be found at antialias[45] = 0x88. This would mean to use an alpha value of 0x88 for the next 12 pixels starting at pixel 45.

Implements SkBlitter.

Definition at line 202 of file SkBlitter_A8.cpp.

                                                                                          {
    uint8_t* device = fDevice.writable_addr8(x, y);
    SkDEBUGCODE(int totalCount = 0;)
 
    for (;;) {
        int count = runs[0];
        SkASSERT(count >= 0);
        if (count == 0) {
            return;
        }
 
        if (antialias[0] == 0xFF) {
            fBWProc(device, fSrc, count);
        } else if (antialias[0] != 0) {
            fAAProc(device, fSrc, count, antialias[0]);
        }
 
        runs += count;
        antialias += count;
        device += count;
 
        SkDEBUGCODE(totalCount += count;)
    }
    SkASSERT(fDevice.width() == totalCount);
}

blitH()

void SkA8_Blitter::blitH ( int  x, int  y, int  width  )

overridevirtual

Blit a horizontal run of one or more pixels.

Implements SkBlitter.

Definition at line 228 of file SkBlitter_A8.cpp.

                                                {
    fBWProc(fDevice.writable_addr8(x, y), fSrc, width);
}

blitMask()

void SkA8_Blitter::blitMask ( const SkMask &  mask, const SkIRect &  clip  )

overridevirtual

Blit a pattern of pixels defined by a rectangle-clipped mask; typically used for text.

Reimplemented from SkBlitter.

Definition at line 259 of file SkBlitter_A8.cpp.

                                                                   {
    if (SkMask::kA8_Format != mask.fFormat) {
        this->INHERITED::blitMask(mask, clip);
        return;
    }
 
    int x = clip.fLeft;
    int y = clip.fTop;
    int width = clip.width();
    int height = clip.height();
 
    uint8_t* dst = fDevice.writable_addr8(x, y);
    const uint8_t* src = mask.getAddr8(x, y);
    const size_t srcRB = mask.fRowBytes;
    const size_t dstRB = fDevice.rowBytes();
 
    while (--height >= 0) {
        for (int i = 0; i < width; ++i) {
            dst[i] = u8_lerp(dst[i], fOneProc(fSrc, dst[i]), src[i]);
        }
        dst += dstRB;
        src += srcRB;
    }
}

blitRect()

void SkA8_Blitter::blitRect ( int  x, int  y, int  width, int  height  )

overridevirtual

Blit a solid rectangle one or more pixels wide.

Reimplemented from SkBlitter.

Definition at line 249 of file SkBlitter_A8.cpp.

                                                               {
    uint8_t* device = fDevice.writable_addr8(x, y);
    const size_t dstRB = fDevice.rowBytes();
 
    while (--height >= 0) {
        fBWProc(device, fSrc, width);
        device += dstRB;
    }
}

blitV()

void SkA8_Blitter::blitV ( int  x, int  y, int  height, SkAlpha  alpha  )

overridevirtual

Blit a vertical run of pixels with a constant alpha value.

Reimplemented from SkBlitter.

Definition at line 232 of file SkBlitter_A8.cpp.

                                                             {
    uint8_t* device = fDevice.writable_addr8(x, y);
    const size_t dstRB = fDevice.rowBytes();
 
    if (aa == 0xFF) {
        while (--height >= 0) {
            *device = fOneProc(fSrc, *device);
            device += dstRB;
        }
    } else if (aa != 0) {
        while (--height >= 0) {
            fAAProc(device, fSrc, 1, aa);
            device += dstRB;
        }
    }
}

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The documentation for this class was generated from the following file:

• third_party/skia/src/core/SkBlitter_A8.cpp