• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * Copyright 2016 Google Inc.
3  *
4  * Use of this source code is governed by a BSD-style license that can be
5  * found in the LICENSE file.
6  */
7 
8 #include "include/core/SkColor.h"
9 #include "include/core/SkPaint.h"
10 #include "include/core/SkShader.h"
11 #include "include/private/SkTo.h"
12 #include "src/core/SkArenaAlloc.h"
13 #include "src/core/SkBlendModePriv.h"
14 #include "src/core/SkBlitter.h"
15 #include "src/core/SkColorFilterBase.h"
16 #include "src/core/SkColorSpacePriv.h"
17 #include "src/core/SkColorSpaceXformSteps.h"
18 #include "src/core/SkMatrixProvider.h"
19 #include "src/core/SkOpts.h"
20 #include "src/core/SkRasterPipeline.h"
21 #include "src/core/SkUtils.h"
22 #include "src/shaders/SkShaderBase.h"
23 
24 class SkRasterPipelineBlitter final : public SkBlitter {
25 public:
26     // This is our common entrypoint for creating the blitter once we've sorted out shaders.
27     static SkBlitter* Create(const SkPixmap&, const SkPaint&, SkArenaAlloc*,
28                              const SkRasterPipeline& shaderPipeline,
29                              bool is_opaque, bool is_constant,
30                              sk_sp<SkShader> clipShader);
31 
SkRasterPipelineBlitter(SkPixmap dst,SkBlendMode blend,SkArenaAlloc * alloc)32     SkRasterPipelineBlitter(SkPixmap dst,
33                             SkBlendMode blend,
34                             SkArenaAlloc* alloc)
35         : fDst(dst)
36         , fBlend(blend)
37         , fAlloc(alloc)
38         , fColorPipeline(alloc)
39     {}
40 
41     void blitH     (int x, int y, int w)                            override;
42     void blitAntiH (int x, int y, const SkAlpha[], const int16_t[]) override;
43     void blitAntiH2(int x, int y, U8CPU a0, U8CPU a1)               override;
44     void blitAntiV2(int x, int y, U8CPU a0, U8CPU a1)               override;
45     void blitMask  (const SkMask&, const SkIRect& clip)             override;
46     void blitRect  (int x, int y, int width, int height)            override;
47     void blitV     (int x, int y, int height, SkAlpha alpha)        override;
48 
49 private:
50     void append_load_dst      (SkRasterPipeline*) const;
51     void append_store         (SkRasterPipeline*) const;
52 
53     // these check internally, and only append if there was a native clipShader
54     void append_clip_scale    (SkRasterPipeline*) const;
55     void append_clip_lerp     (SkRasterPipeline*) const;
56 
57     SkPixmap               fDst;
58     SkBlendMode            fBlend;
59     SkArenaAlloc*          fAlloc;
60     SkRasterPipeline       fColorPipeline;
61     // set to pipeline storage (for alpha) if we have a clipShader
62     void*                  fClipShaderBuffer = nullptr; // "native" : float or U16
63 
64     SkRasterPipeline_MemoryCtx
65         fDstPtr       = {nullptr,0},  // Always points to the top-left of fDst.
66         fMaskPtr      = {nullptr,0};  // Updated each call to blitMask().
67     SkRasterPipeline_EmbossCtx fEmbossCtx;  // Used only for k3D_Format masks.
68 
69     // We may be able to specialize blitH() or blitRect() into a memset.
70     void   (*fMemset2D)(SkPixmap*, int x,int y, int w,int h, uint64_t color) = nullptr;
71     uint64_t fMemsetColor = 0;   // Big enough for largest memsettable dst format, F16.
72 
73     // Built lazily on first use.
74     std::function<void(size_t, size_t, size_t, size_t)> fBlitRect,
75                                                         fBlitAntiH,
76                                                         fBlitMaskA8,
77                                                         fBlitMaskLCD16,
78                                                         fBlitMask3D;
79 
80     // These values are pointed to by the blit pipelines above,
81     // which allows us to adjust them from call to call.
82     float fCurrentCoverage = 0.0f;
83     float fDitherRate      = 0.0f;
84 
85     using INHERITED = SkBlitter;
86 };
87 
SkCreateRasterPipelineBlitter(const SkPixmap & dst,const SkPaint & paint,const SkMatrixProvider & matrixProvider,SkArenaAlloc * alloc,sk_sp<SkShader> clipShader)88 SkBlitter* SkCreateRasterPipelineBlitter(const SkPixmap& dst,
89                                          const SkPaint& paint,
90                                          const SkMatrixProvider& matrixProvider,
91                                          SkArenaAlloc* alloc,
92                                          sk_sp<SkShader> clipShader) {
93     SkColorSpace* dstCS = dst.colorSpace();
94     SkColorType dstCT = dst.colorType();
95     SkColor4f paintColor = paint.getColor4f();
96     SkColorSpaceXformSteps(sk_srgb_singleton(), kUnpremul_SkAlphaType,
97                            dstCS,               kUnpremul_SkAlphaType).apply(paintColor.vec());
98 
99     auto shader = as_SB(paint.getShader());
100 
101     SkRasterPipeline_<256> shaderPipeline;
102     if (!shader) {
103         // Having no shader makes things nice and easy... just use the paint color.
104         shaderPipeline.append_constant_color(alloc, paintColor.premul().vec());
105         bool is_opaque    = paintColor.fA == 1.0f,
106              is_constant  = true;
107         return SkRasterPipelineBlitter::Create(dst, paint, alloc,
108                                                shaderPipeline, is_opaque, is_constant,
109                                                std::move(clipShader));
110     }
111 
112     bool is_opaque    = shader->isOpaque() && paintColor.fA == 1.0f;
113     bool is_constant  = shader->isConstant();
114 
115     if (shader->appendStages(
116                 {&shaderPipeline, alloc, dstCT, dstCS, paint, nullptr, matrixProvider})) {
117         if (paintColor.fA != 1.0f) {
118             shaderPipeline.append(SkRasterPipeline::scale_1_float,
119                                   alloc->make<float>(paintColor.fA));
120         }
121         return SkRasterPipelineBlitter::Create(dst, paint, alloc,
122                                                shaderPipeline, is_opaque, is_constant,
123                                                std::move(clipShader));
124     }
125 
126     // The shader can't draw with SkRasterPipeline.
127     return nullptr;
128 }
129 
SkCreateRasterPipelineBlitter(const SkPixmap & dst,const SkPaint & paint,const SkRasterPipeline & shaderPipeline,bool is_opaque,SkArenaAlloc * alloc,sk_sp<SkShader> clipShader)130 SkBlitter* SkCreateRasterPipelineBlitter(const SkPixmap& dst,
131                                          const SkPaint& paint,
132                                          const SkRasterPipeline& shaderPipeline,
133                                          bool is_opaque,
134                                          SkArenaAlloc* alloc,
135                                          sk_sp<SkShader> clipShader) {
136     bool is_constant = false;  // If this were the case, it'd be better to just set a paint color.
137     return SkRasterPipelineBlitter::Create(dst, paint, alloc,
138                                            shaderPipeline, is_opaque, is_constant,
139                                            clipShader);
140 }
141 
Create(const SkPixmap & dst,const SkPaint & paint,SkArenaAlloc * alloc,const SkRasterPipeline & shaderPipeline,bool is_opaque,bool is_constant,sk_sp<SkShader> clipShader)142 SkBlitter* SkRasterPipelineBlitter::Create(const SkPixmap& dst,
143                                            const SkPaint& paint,
144                                            SkArenaAlloc* alloc,
145                                            const SkRasterPipeline& shaderPipeline,
146                                            bool is_opaque,
147                                            bool is_constant,
148                                            sk_sp<SkShader> clipShader) {
149     auto blitter = alloc->make<SkRasterPipelineBlitter>(dst,
150                                                         paint.getBlendMode(),
151                                                         alloc);
152 
153 
154     // Our job in this factory is to fill out the blitter's color pipeline.
155     // This is the common front of the full blit pipelines, each constructed lazily on first use.
156     // The full blit pipelines handle reading and writing the dst, blending, coverage, dithering.
157     auto colorPipeline = &blitter->fColorPipeline;
158 
159     if (clipShader) {
160         auto clipP = colorPipeline;
161         SkPaint clipPaint;  // just need default values
162         SkColorType clipCT = kRGBA_8888_SkColorType;
163         SkColorSpace* clipCS = nullptr;
164         SkSimpleMatrixProvider clipMatrixProvider(SkMatrix::I());
165         SkStageRec rec = {clipP, alloc, clipCT, clipCS, clipPaint, nullptr, clipMatrixProvider};
166         if (as_SB(clipShader)->appendStages(rec)) {
167             struct Storage {
168                 // large enough for highp (float) or lowp(U16)
169                 float   fA[SkRasterPipeline_kMaxStride];
170             };
171             auto storage = alloc->make<Storage>();
172             clipP->append(SkRasterPipeline::store_src_a, storage->fA);
173             blitter->fClipShaderBuffer = storage->fA;
174             is_constant = false;
175         } else {
176             return nullptr;
177         }
178     }
179 
180     // Let's get the shader in first.
181     colorPipeline->extend(shaderPipeline);
182 
183     // If there's a color filter it comes next.
184     if (auto colorFilter = paint.getColorFilter()) {
185         SkSimpleMatrixProvider matrixProvider(SkMatrix::I());
186         SkStageRec rec = {
187             colorPipeline, alloc, dst.colorType(), dst.colorSpace(), paint, nullptr, matrixProvider
188         };
189         if (!as_CFB(colorFilter)->appendStages(rec, is_opaque)) {
190             return nullptr;
191         }
192         is_opaque = is_opaque && as_CFB(colorFilter)->isAlphaUnchanged();
193     }
194 
195     // Not all formats make sense to dither (think, F16).  We set their dither rate
196     // to zero.  We only dither non-constant shaders, so is_constant won't change here.
197     if (paint.isDither() && !is_constant) {
198         switch (dst.info().colorType()) {
199             case kARGB_4444_SkColorType:    blitter->fDitherRate =   1/15.0f; break;
200             case   kRGB_565_SkColorType:    blitter->fDitherRate =   1/63.0f; break;
201             case    kGray_8_SkColorType:
202             case  kRGB_888x_SkColorType:
203             case kRGBA_8888_SkColorType:
204             case kBGRA_8888_SkColorType:    blitter->fDitherRate =  1/255.0f; break;
205             case kRGB_101010x_SkColorType:
206             case kRGBA_1010102_SkColorType:
207             case kBGR_101010x_SkColorType:
208             case kBGRA_1010102_SkColorType: blitter->fDitherRate = 1/1023.0f; break;
209 
210             case kUnknown_SkColorType:
211             case kAlpha_8_SkColorType:
212             case kRGBA_F16_SkColorType:
213             case kRGBA_F16Norm_SkColorType:
214             case kRGBA_F32_SkColorType:
215             case kR8G8_unorm_SkColorType:
216             case kA16_float_SkColorType:
217             case kA16_unorm_SkColorType:
218             case kR16G16_float_SkColorType:
219             case kR16G16_unorm_SkColorType:
220             case kR16G16B16A16_unorm_SkColorType: blitter->fDitherRate = 0.0f; break;
221         }
222         if (blitter->fDitherRate > 0.0f) {
223             colorPipeline->append(SkRasterPipeline::dither, &blitter->fDitherRate);
224         }
225     }
226 
227     // We're logically done here.  The code between here and return blitter is all optimization.
228 
229     // A pipeline that's still constant here can collapse back into a constant color.
230     if (is_constant) {
231         SkColor4f constantColor;
232         SkRasterPipeline_MemoryCtx constantColorPtr = { &constantColor, 0 };
233         colorPipeline->append_gamut_clamp_if_normalized(dst.info());
234         colorPipeline->append(SkRasterPipeline::store_f32, &constantColorPtr);
235         colorPipeline->run(0,0,1,1);
236         colorPipeline->reset();
237         colorPipeline->append_constant_color(alloc, constantColor);
238 
239         is_opaque = constantColor.fA == 1.0f;
240     }
241 
242     // We can strength-reduce SrcOver into Src when opaque.
243     if (is_opaque && blitter->fBlend == SkBlendMode::kSrcOver) {
244         blitter->fBlend = SkBlendMode::kSrc;
245     }
246 
247     // When we're drawing a constant color in Src mode, we can sometimes just memset.
248     // (The previous two optimizations help find more opportunities for this one.)
249     if (is_constant && blitter->fBlend == SkBlendMode::kSrc) {
250         // Run our color pipeline all the way through to produce what we'd memset when we can.
251         // Not all blits can memset, so we need to keep colorPipeline too.
252         SkRasterPipeline_<256> p;
253         p.extend(*colorPipeline);
254         p.append_gamut_clamp_if_normalized(dst.info());
255         blitter->fDstPtr = SkRasterPipeline_MemoryCtx{&blitter->fMemsetColor, 0};
256         blitter->append_store(&p);
257         p.run(0,0,1,1);
258 
259         switch (blitter->fDst.shiftPerPixel()) {
260             case 0: blitter->fMemset2D = [](SkPixmap* dst, int x,int y, int w,int h, uint64_t c) {
261                 void* p = dst->writable_addr(x,y);
262                 while (h --> 0) {
263                     memset(p, c, w);
264                     p = SkTAddOffset<void>(p, dst->rowBytes());
265                 }
266             }; break;
267 
268             case 1: blitter->fMemset2D = [](SkPixmap* dst, int x,int y, int w,int h, uint64_t c) {
269                 SkOpts::rect_memset16(dst->writable_addr16(x,y), c, w, dst->rowBytes(), h);
270             }; break;
271 
272             case 2: blitter->fMemset2D = [](SkPixmap* dst, int x,int y, int w,int h, uint64_t c) {
273                 SkOpts::rect_memset32(dst->writable_addr32(x,y), c, w, dst->rowBytes(), h);
274             }; break;
275 
276             case 3: blitter->fMemset2D = [](SkPixmap* dst, int x,int y, int w,int h, uint64_t c) {
277                 SkOpts::rect_memset64(dst->writable_addr64(x,y), c, w, dst->rowBytes(), h);
278             }; break;
279 
280             // TODO(F32)?
281         }
282     }
283 
284     blitter->fDstPtr = SkRasterPipeline_MemoryCtx{
285         blitter->fDst.writable_addr(),
286         blitter->fDst.rowBytesAsPixels(),
287     };
288 
289     return blitter;
290 }
291 
append_load_dst(SkRasterPipeline * p) const292 void SkRasterPipelineBlitter::append_load_dst(SkRasterPipeline* p) const {
293     p->append_load_dst(fDst.info().colorType(), &fDstPtr);
294     if (fDst.info().alphaType() == kUnpremul_SkAlphaType) {
295         p->append(SkRasterPipeline::premul_dst);
296     }
297 }
298 
append_store(SkRasterPipeline * p) const299 void SkRasterPipelineBlitter::append_store(SkRasterPipeline* p) const {
300     if (fDst.info().alphaType() == kUnpremul_SkAlphaType) {
301         p->append(SkRasterPipeline::unpremul);
302     }
303     p->append_store(fDst.info().colorType(), &fDstPtr);
304 }
305 
append_clip_scale(SkRasterPipeline * p) const306 void SkRasterPipelineBlitter::append_clip_scale(SkRasterPipeline* p) const {
307     if (fClipShaderBuffer) {
308         p->append(SkRasterPipeline::scale_native, fClipShaderBuffer);
309     }
310 }
311 
append_clip_lerp(SkRasterPipeline * p) const312 void SkRasterPipelineBlitter::append_clip_lerp(SkRasterPipeline* p) const {
313     if (fClipShaderBuffer) {
314         p->append(SkRasterPipeline::lerp_native, fClipShaderBuffer);
315     }
316 }
317 
blitH(int x,int y,int w)318 void SkRasterPipelineBlitter::blitH(int x, int y, int w) {
319     this->blitRect(x,y,w,1);
320 }
321 
blitRect(int x,int y,int w,int h)322 void SkRasterPipelineBlitter::blitRect(int x, int y, int w, int h) {
323     if (fMemset2D) {
324         fMemset2D(&fDst, x,y, w,h, fMemsetColor);
325         return;
326     }
327 
328     if (!fBlitRect) {
329         SkRasterPipeline p(fAlloc);
330         p.extend(fColorPipeline);
331         p.append_gamut_clamp_if_normalized(fDst.info());
332         if (fBlend == SkBlendMode::kSrcOver
333                 && (fDst.info().colorType() == kRGBA_8888_SkColorType ||
334                     fDst.info().colorType() == kBGRA_8888_SkColorType)
335                 && !fDst.colorSpace()
336                 && fDst.info().alphaType() != kUnpremul_SkAlphaType
337                 && fDitherRate == 0.0f) {
338             if (fDst.info().colorType() == kBGRA_8888_SkColorType) {
339                 p.append(SkRasterPipeline::swap_rb);
340             }
341             this->append_clip_scale(&p);
342             p.append(SkRasterPipeline::srcover_rgba_8888, &fDstPtr);
343         } else {
344             if (fBlend != SkBlendMode::kSrc) {
345                 this->append_load_dst(&p);
346                 SkBlendMode_AppendStages(fBlend, &p);
347                 this->append_clip_lerp(&p);
348             } else if (fClipShaderBuffer) {
349                 this->append_load_dst(&p);
350                 this->append_clip_lerp(&p);
351             }
352             this->append_store(&p);
353         }
354         fBlitRect = p.compile();
355     }
356 
357     fBlitRect(x,y,w,h);
358 }
359 
blitAntiH(int x,int y,const SkAlpha aa[],const int16_t runs[])360 void SkRasterPipelineBlitter::blitAntiH(int x, int y, const SkAlpha aa[], const int16_t runs[]) {
361     if (!fBlitAntiH) {
362         SkRasterPipeline p(fAlloc);
363         p.extend(fColorPipeline);
364         p.append_gamut_clamp_if_normalized(fDst.info());
365         if (SkBlendMode_ShouldPreScaleCoverage(fBlend, /*rgb_coverage=*/false)) {
366             p.append(SkRasterPipeline::scale_1_float, &fCurrentCoverage);
367             this->append_clip_scale(&p);
368             this->append_load_dst(&p);
369             SkBlendMode_AppendStages(fBlend, &p);
370         } else {
371             this->append_load_dst(&p);
372             SkBlendMode_AppendStages(fBlend, &p);
373             p.append(SkRasterPipeline::lerp_1_float, &fCurrentCoverage);
374             this->append_clip_lerp(&p);
375         }
376 
377         this->append_store(&p);
378         fBlitAntiH = p.compile();
379     }
380 
381     for (int16_t run = *runs; run > 0; run = *runs) {
382         switch (*aa) {
383             case 0x00:                       break;
384             case 0xff: this->blitH(x,y,run); break;
385             default:
386                 fCurrentCoverage = *aa * (1/255.0f);
387                 fBlitAntiH(x,y,run,1);
388         }
389         x    += run;
390         runs += run;
391         aa   += run;
392     }
393 }
394 
blitAntiH2(int x,int y,U8CPU a0,U8CPU a1)395 void SkRasterPipelineBlitter::blitAntiH2(int x, int y, U8CPU a0, U8CPU a1) {
396     SkIRect clip = {x,y, x+2,y+1};
397     uint8_t coverage[] = { (uint8_t)a0, (uint8_t)a1 };
398 
399     SkMask mask;
400     mask.fImage    = coverage;
401     mask.fBounds   = clip;
402     mask.fRowBytes = 2;
403     mask.fFormat   = SkMask::kA8_Format;
404 
405     this->blitMask(mask, clip);
406 }
407 
blitAntiV2(int x,int y,U8CPU a0,U8CPU a1)408 void SkRasterPipelineBlitter::blitAntiV2(int x, int y, U8CPU a0, U8CPU a1) {
409     SkIRect clip = {x,y, x+1,y+2};
410     uint8_t coverage[] = { (uint8_t)a0, (uint8_t)a1 };
411 
412     SkMask mask;
413     mask.fImage    = coverage;
414     mask.fBounds   = clip;
415     mask.fRowBytes = 1;
416     mask.fFormat   = SkMask::kA8_Format;
417 
418     this->blitMask(mask, clip);
419 }
420 
blitV(int x,int y,int height,SkAlpha alpha)421 void SkRasterPipelineBlitter::blitV(int x, int y, int height, SkAlpha alpha) {
422     SkIRect clip = {x,y, x+1,y+height};
423 
424     SkMask mask;
425     mask.fImage    = &alpha;
426     mask.fBounds   = clip;
427     mask.fRowBytes = 0;     // so we reuse the 1 "row" for all of height
428     mask.fFormat   = SkMask::kA8_Format;
429 
430     this->blitMask(mask, clip);
431 }
432 
blitMask(const SkMask & mask,const SkIRect & clip)433 void SkRasterPipelineBlitter::blitMask(const SkMask& mask, const SkIRect& clip) {
434     if (mask.fFormat == SkMask::kBW_Format) {
435         // TODO: native BW masks?
436         return INHERITED::blitMask(mask, clip);
437     }
438 
439     // ARGB and SDF masks shouldn't make it here.
440     SkASSERT(mask.fFormat == SkMask::kA8_Format
441           || mask.fFormat == SkMask::kLCD16_Format
442           || mask.fFormat == SkMask::k3D_Format);
443 
444     auto extract_mask_plane = [&mask](int plane, SkRasterPipeline_MemoryCtx* ctx) {
445         // LCD is 16-bit per pixel; A8 and 3D are 8-bit per pixel.
446         size_t bpp = mask.fFormat == SkMask::kLCD16_Format ? 2 : 1;
447 
448         // Select the right mask plane.  Usually plane == 0 and this is just mask.fImage.
449         auto ptr = (uintptr_t)mask.fImage
450                  + plane * mask.computeImageSize();
451 
452         // Update ctx to point "into" this current mask, but lined up with fDstPtr at (0,0).
453         // This sort of trickery upsets UBSAN (pointer-overflow) so our ptr must be a uintptr_t.
454         // mask.fRowBytes is a uint32_t, which would break our addressing math on 64-bit builds.
455         size_t rowBytes = mask.fRowBytes;
456         ctx->stride = rowBytes / bpp;
457         ctx->pixels = (void*)(ptr - mask.fBounds.left() * bpp
458                                   - mask.fBounds.top()  * rowBytes);
459     };
460 
461     extract_mask_plane(0, &fMaskPtr);
462     if (mask.fFormat == SkMask::k3D_Format) {
463         extract_mask_plane(1, &fEmbossCtx.mul);
464         extract_mask_plane(2, &fEmbossCtx.add);
465     }
466 
467     // Lazily build whichever pipeline we need, specialized for each mask format.
468     if (mask.fFormat == SkMask::kA8_Format && !fBlitMaskA8) {
469         SkRasterPipeline p(fAlloc);
470         p.extend(fColorPipeline);
471         p.append_gamut_clamp_if_normalized(fDst.info());
472         if (SkBlendMode_ShouldPreScaleCoverage(fBlend, /*rgb_coverage=*/false)) {
473             p.append(SkRasterPipeline::scale_u8, &fMaskPtr);
474             this->append_clip_scale(&p);
475             this->append_load_dst(&p);
476             SkBlendMode_AppendStages(fBlend, &p);
477         } else {
478             this->append_load_dst(&p);
479             SkBlendMode_AppendStages(fBlend, &p);
480             p.append(SkRasterPipeline::lerp_u8, &fMaskPtr);
481             this->append_clip_lerp(&p);
482         }
483         this->append_store(&p);
484         fBlitMaskA8 = p.compile();
485     }
486     if (mask.fFormat == SkMask::kLCD16_Format && !fBlitMaskLCD16) {
487         SkRasterPipeline p(fAlloc);
488         p.extend(fColorPipeline);
489         p.append_gamut_clamp_if_normalized(fDst.info());
490         if (SkBlendMode_ShouldPreScaleCoverage(fBlend, /*rgb_coverage=*/true)) {
491             // Somewhat unusually, scale_565 needs dst loaded first.
492             this->append_load_dst(&p);
493             p.append(SkRasterPipeline::scale_565, &fMaskPtr);
494             this->append_clip_scale(&p);
495             SkBlendMode_AppendStages(fBlend, &p);
496         } else {
497             this->append_load_dst(&p);
498             SkBlendMode_AppendStages(fBlend, &p);
499             p.append(SkRasterPipeline::lerp_565, &fMaskPtr);
500             this->append_clip_lerp(&p);
501         }
502         this->append_store(&p);
503         fBlitMaskLCD16 = p.compile();
504     }
505     if (mask.fFormat == SkMask::k3D_Format && !fBlitMask3D) {
506         SkRasterPipeline p(fAlloc);
507         p.extend(fColorPipeline);
508         // This bit is where we differ from kA8_Format:
509         p.append(SkRasterPipeline::emboss, &fEmbossCtx);
510         // Now onward just as kA8.
511         p.append_gamut_clamp_if_normalized(fDst.info());
512         if (SkBlendMode_ShouldPreScaleCoverage(fBlend, /*rgb_coverage=*/false)) {
513             p.append(SkRasterPipeline::scale_u8, &fMaskPtr);
514             this->append_clip_scale(&p);
515             this->append_load_dst(&p);
516             SkBlendMode_AppendStages(fBlend, &p);
517         } else {
518             this->append_load_dst(&p);
519             SkBlendMode_AppendStages(fBlend, &p);
520             p.append(SkRasterPipeline::lerp_u8, &fMaskPtr);
521             this->append_clip_lerp(&p);
522         }
523         this->append_store(&p);
524         fBlitMask3D = p.compile();
525     }
526 
527     std::function<void(size_t,size_t,size_t,size_t)>* blitter = nullptr;
528     switch (mask.fFormat) {
529         case SkMask::kA8_Format:    blitter = &fBlitMaskA8;    break;
530         case SkMask::kLCD16_Format: blitter = &fBlitMaskLCD16; break;
531         case SkMask::k3D_Format:    blitter = &fBlitMask3D;    break;
532         default:
533             SkASSERT(false);
534             return;
535     }
536 
537     SkASSERT(blitter);
538     (*blitter)(clip.left(),clip.top(), clip.width(),clip.height());
539 }
540