SkAAClip::Builder::Blitter Class Reference

Inheritance diagram for SkAAClip::Builder::Blitter:

Public Member Functions
	Blitter (Builder *builder)
void	finish ()
void	blitV (int x, int y, int height, SkAlpha alpha) override
void	blitRect (int x, int y, int width, int height) override
	Blit a solid rectangle one or more pixels wide.
void	blitAntiRect (int x, int y, int width, int height, SkAlpha leftAlpha, SkAlpha rightAlpha) override
void	blitMask (const SkMask &, const SkIRect &clip) override
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 alpha[], const int16_t runs[]) override
Public Member Functions inherited from SkBlitter
virtual	~SkBlitter ()
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 685 of file SkAAClip.cpp.

Constructor & Destructor Documentation

Blitter()

SkAAClip::Builder::Blitter::Blitter ( Builder *  builder )

inline

Definition at line 706 of file SkAAClip.cpp.

                              {
        fBuilder = builder;
        fLeft = builder->fBounds.fLeft;
        fRight = builder->fBounds.fRight;
        fMinY = SK_MaxS32;
        fLastY = -SK_MaxS32;    // sentinel
    }

Member Function Documentation

blitAntiH()

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

inlineoverridevirtual

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 765 of file SkAAClip.cpp.

                                                                                       {
        this->recordMinY(y);
        this->checkForYGap(y);
        for (;;) {
            int count = *runs;
            if (count <= 0) {
                return;
            }
 
            // The supersampler's buffer can be the width of the device, so
            // we may have to trim the run to our bounds. Previously, we assert that
            // the extra spans are always alpha==0.
            // However, the analytic AA is too sensitive to precision errors
            // so it may have extra spans with very tiny alpha because after several
            // arithmatic operations, the edge may bleed the path boundary a little bit.
            // Therefore, instead of always asserting alpha==0, we assert alpha < 0x10.
            int localX = x;
            int localCount = count;
            if (x < fLeft) {
                SkASSERT(0x10 > *alpha);
                int gap = fLeft - x;
                SkASSERT(gap <= count);
                localX += gap;
                localCount -= gap;
            }
            int right = x + count;
            if (right > fRight) {
                SkASSERT(0x10 > *alpha);
                localCount -= right - fRight;
                SkASSERT(localCount >= 0);
            }
 
            if (localCount) {
                fBuilder->addRun(localX, y, *alpha, localCount);
            }
            // Next run
            runs += count;
            alpha += count;
            x += count;
        }
    }

blitAntiRect()

void SkAAClip::Builder::Blitter::blitAntiRect ( int  x, int  y, int  width, int  height, SkAlpha  leftAlpha, SkAlpha  rightAlpha  )

inlineoverridevirtual

Blit a rectangle with one alpha-blended column on the left, width (zero or more) opaque pixels, and one alpha-blended column on the right. The result will always be at least two pixels wide.

Default implementation doesn't check for easy optimizations such as alpha == 255; also uses blitV(), which some subclasses may not support.

Reimplemented from SkBlitter.

Definition at line 748 of file SkAAClip.cpp.

                                                                      {
        this->recordMinY(y);
        this->checkForYGap(y);
        fBuilder->addAntiRectRun(x, y, width, height, leftAlpha, rightAlpha);
        fLastY = y + height - 1;
    }

blitH()

void SkAAClip::Builder::Blitter::blitH ( int  x, int  y, int  width  )

inlineoverridevirtual

Blit a horizontal run of one or more pixels.

Implements SkBlitter.

Definition at line 759 of file SkAAClip.cpp.

                                                 {
        this->recordMinY(y);
        this->checkForYGap(y);
        fBuilder->addRun(x, y, 0xFF, width);
    }

blitMask()

void SkAAClip::Builder::Blitter::blitMask ( const SkMask &  mask, const SkIRect &  clip  )

inlineoverridevirtual

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

Reimplemented from SkBlitter.

Definition at line 756 of file SkAAClip.cpp.

        { unexpected(); }

blitRect()

void SkAAClip::Builder::Blitter::blitRect ( int  x, int  y, int  width, int  height  )

inlineoverridevirtual

Blit a solid rectangle one or more pixels wide.

Reimplemented from SkBlitter.

Definition at line 741 of file SkAAClip.cpp.

                                                                {
        this->recordMinY(y);
        this->checkForYGap(y);
        fBuilder->addRectRun(x, y, width, height);
        fLastY = y + height - 1;
    }

blitV()

void SkAAClip::Builder::Blitter::blitV ( int  x, int  y, int  height, SkAlpha  alpha  )

inlineoverridevirtual

Must evaluate clips in scan-line order, so don't want to allow blitV(), but an AAClip can be clipped down to a single pixel wide, so we must support it (given AntiRect semantics: minimum width is 2). Instead we'll rely on the runtime asserts to guarantee Y monotonicity; any failure cases that misses may have minor artifacts.

Reimplemented from SkBlitter.

Definition at line 727 of file SkAAClip.cpp.

                                                                 {
        if (height == 1) {
            // We're still in scan-line order if height is 1
            // This is useful for Analytic AA
            const SkAlpha alphas[2] = {alpha, 0};
            const int16_t runs[2] = {1, 0};
            this->blitAntiH(x, y, alphas, runs);
        } else {
            this->recordMinY(y);
            fBuilder->addColumn(x, y, alpha, height);
            fLastY = y + height - 1;
        }
    }

finish()

void SkAAClip::Builder::Blitter::finish ( )

inline

Definition at line 714 of file SkAAClip.cpp.

                  {
        if (fMinY < SK_MaxS32) {
            fBuilder->fMinY = fMinY;
        }
    }

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

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