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1 /*
2 * Copyright 2017 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 "SkShadowUtils.h"
9 #include "SkCanvas.h"
10 #include "SkColorFilter.h"
11 #include "SkColorPriv.h"
12 #include "SkDevice.h"
13 #include "SkDrawShadowRec.h"
14 #include "SkPath.h"
15 #include "SkPM4f.h"
16 #include "SkRandom.h"
17 #include "SkRasterPipeline.h"
18 #include "SkResourceCache.h"
19 #include "SkShadowTessellator.h"
20 #include "SkString.h"
21 #include "SkTLazy.h"
22 #include "SkVertices.h"
23 #if SK_SUPPORT_GPU
24 #include "GrShape.h"
25 #include "effects/GrBlurredEdgeFragmentProcessor.h"
26 #endif
27 
28 /**
29 *  Gaussian color filter -- produces a Gaussian ramp based on the color's B value,
30 *                           then blends with the color's G value.
31 *                           Final result is black with alpha of Gaussian(B)*G.
32 *                           The assumption is that the original color's alpha is 1.
33 */
34 class SK_API SkGaussianColorFilter : public SkColorFilter {
35 public:
Make()36     static sk_sp<SkColorFilter> Make() {
37         return sk_sp<SkColorFilter>(new SkGaussianColorFilter);
38     }
39 
40 #if SK_SUPPORT_GPU
41     sk_sp<GrFragmentProcessor> asFragmentProcessor(GrContext*, SkColorSpace*) const override;
42 #endif
43 
44     SK_TO_STRING_OVERRIDE()
45     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkGaussianColorFilter)
46 
47 protected:
flatten(SkWriteBuffer &) const48     void flatten(SkWriteBuffer&) const override {}
onAppendStages(SkRasterPipeline * pipeline,SkColorSpace * dstCS,SkArenaAlloc * alloc,bool shaderIsOpaque) const49     void onAppendStages(SkRasterPipeline* pipeline, SkColorSpace* dstCS, SkArenaAlloc* alloc,
50                         bool shaderIsOpaque) const override {
51         pipeline->append(SkRasterPipeline::gauss_a_to_rgba);
52     }
53 private:
SkGaussianColorFilter()54     SkGaussianColorFilter() : INHERITED() {}
55 
56     typedef SkColorFilter INHERITED;
57 };
58 
CreateProc(SkReadBuffer &)59 sk_sp<SkFlattenable> SkGaussianColorFilter::CreateProc(SkReadBuffer&) {
60     return Make();
61 }
62 
63 #ifndef SK_IGNORE_TO_STRING
toString(SkString * str) const64 void SkGaussianColorFilter::toString(SkString* str) const {
65     str->append("SkGaussianColorFilter ");
66 }
67 #endif
68 
69 #if SK_SUPPORT_GPU
70 
asFragmentProcessor(GrContext *,SkColorSpace *) const71 sk_sp<GrFragmentProcessor> SkGaussianColorFilter::asFragmentProcessor(GrContext*,
72                                                                       SkColorSpace*) const {
73     return GrBlurredEdgeFragmentProcessor::Make(GrBlurredEdgeFragmentProcessor::kGaussian_Mode);
74 }
75 #endif
76 
77 ///////////////////////////////////////////////////////////////////////////////////////////////////
78 
79 namespace {
80 
resource_cache_shared_id()81 uint64_t resource_cache_shared_id() {
82     return 0x2020776f64616873llu;  // 'shadow  '
83 }
84 
85 /** Factory for an ambient shadow mesh with particular shadow properties. */
86 struct AmbientVerticesFactory {
87     SkScalar fOccluderHeight = SK_ScalarNaN;  // NaN so that isCompatible will fail until init'ed.
88     bool fTransparent;
89     SkVector fOffset;
90 
isCompatible__anon33e536640111::AmbientVerticesFactory91     bool isCompatible(const AmbientVerticesFactory& that, SkVector* translate) const {
92         if (fOccluderHeight != that.fOccluderHeight || fTransparent != that.fTransparent) {
93             return false;
94         }
95         *translate = that.fOffset;
96         return true;
97     }
98 
makeVertices__anon33e536640111::AmbientVerticesFactory99     sk_sp<SkVertices> makeVertices(const SkPath& path, const SkMatrix& ctm,
100                                    SkVector* translate) const {
101         SkPoint3 zParams = SkPoint3::Make(0, 0, fOccluderHeight);
102         // pick a canonical place to generate shadow
103         SkMatrix noTrans(ctm);
104         if (!ctm.hasPerspective()) {
105             noTrans[SkMatrix::kMTransX] = 0;
106             noTrans[SkMatrix::kMTransY] = 0;
107         }
108         *translate = fOffset;
109         return SkShadowTessellator::MakeAmbient(path, noTrans, zParams, fTransparent);
110     }
111 };
112 
113 /** Factory for an spot shadow mesh with particular shadow properties. */
114 struct SpotVerticesFactory {
115     enum class OccluderType {
116         // The umbra cannot be dropped out because either the occluder is not opaque,
117         // or the center of the umbra is visible.
118         kTransparent,
119         // The umbra can be dropped where it is occluded.
120         kOpaquePartialUmbra,
121         // It is known that the entire umbra is occluded.
122         kOpaqueNoUmbra
123     };
124 
125     SkVector fOffset;
126     SkPoint  fLocalCenter;
127     SkScalar fOccluderHeight = SK_ScalarNaN; // NaN so that isCompatible will fail until init'ed.
128     SkPoint3 fDevLightPos;
129     SkScalar fLightRadius;
130     OccluderType fOccluderType;
131 
isCompatible__anon33e536640111::SpotVerticesFactory132     bool isCompatible(const SpotVerticesFactory& that, SkVector* translate) const {
133         if (fOccluderHeight != that.fOccluderHeight || fDevLightPos.fZ != that.fDevLightPos.fZ ||
134             fLightRadius != that.fLightRadius || fOccluderType != that.fOccluderType) {
135             return false;
136         }
137         switch (fOccluderType) {
138             case OccluderType::kTransparent:
139             case OccluderType::kOpaqueNoUmbra:
140                 // 'this' and 'that' will either both have no umbra removed or both have all the
141                 // umbra removed.
142                 *translate = that.fOffset;
143                 return true;
144             case OccluderType::kOpaquePartialUmbra:
145                 // In this case we partially remove the umbra differently for 'this' and 'that'
146                 // if the offsets don't match.
147                 if (fOffset == that.fOffset) {
148                     translate->set(0, 0);
149                     return true;
150                 }
151                 return false;
152         }
153         SkFAIL("Uninitialized occluder type?");
154         return false;
155     }
156 
makeVertices__anon33e536640111::SpotVerticesFactory157     sk_sp<SkVertices> makeVertices(const SkPath& path, const SkMatrix& ctm,
158                                    SkVector* translate) const {
159         bool transparent = OccluderType::kTransparent == fOccluderType;
160         SkPoint3 zParams = SkPoint3::Make(0, 0, fOccluderHeight);
161         if (ctm.hasPerspective() || OccluderType::kOpaquePartialUmbra == fOccluderType) {
162             translate->set(0, 0);
163             return SkShadowTessellator::MakeSpot(path, ctm, zParams,
164                                                  fDevLightPos, fLightRadius, transparent);
165         } else {
166             // pick a canonical place to generate shadow, with light centered over path
167             SkMatrix noTrans(ctm);
168             noTrans[SkMatrix::kMTransX] = 0;
169             noTrans[SkMatrix::kMTransY] = 0;
170             SkPoint devCenter(fLocalCenter);
171             noTrans.mapPoints(&devCenter, 1);
172             SkPoint3 centerLightPos = SkPoint3::Make(devCenter.fX, devCenter.fY, fDevLightPos.fZ);
173             *translate = fOffset;
174             return SkShadowTessellator::MakeSpot(path, noTrans, zParams,
175                                                  centerLightPos, fLightRadius, transparent);
176         }
177     }
178 };
179 
180 /**
181  * This manages a set of tessellations for a given shape in the cache. Because SkResourceCache
182  * records are immutable this is not itself a Rec. When we need to update it we return this on
183  * the FindVisitor and let the cache destroy the Rec. We'll update the tessellations and then add
184  * a new Rec with an adjusted size for any deletions/additions.
185  */
186 class CachedTessellations : public SkRefCnt {
187 public:
size() const188     size_t size() const { return fAmbientSet.size() + fSpotSet.size(); }
189 
find(const AmbientVerticesFactory & ambient,const SkMatrix & matrix,SkVector * translate) const190     sk_sp<SkVertices> find(const AmbientVerticesFactory& ambient, const SkMatrix& matrix,
191                            SkVector* translate) const {
192         return fAmbientSet.find(ambient, matrix, translate);
193     }
194 
add(const SkPath & devPath,const AmbientVerticesFactory & ambient,const SkMatrix & matrix,SkVector * translate)195     sk_sp<SkVertices> add(const SkPath& devPath, const AmbientVerticesFactory& ambient,
196                           const SkMatrix& matrix, SkVector* translate) {
197         return fAmbientSet.add(devPath, ambient, matrix, translate);
198     }
199 
find(const SpotVerticesFactory & spot,const SkMatrix & matrix,SkVector * translate) const200     sk_sp<SkVertices> find(const SpotVerticesFactory& spot, const SkMatrix& matrix,
201                            SkVector* translate) const {
202         return fSpotSet.find(spot, matrix, translate);
203     }
204 
add(const SkPath & devPath,const SpotVerticesFactory & spot,const SkMatrix & matrix,SkVector * translate)205     sk_sp<SkVertices> add(const SkPath& devPath, const SpotVerticesFactory& spot,
206                           const SkMatrix& matrix, SkVector* translate) {
207         return fSpotSet.add(devPath, spot, matrix, translate);
208     }
209 
210 private:
211     template <typename FACTORY, int MAX_ENTRIES>
212     class Set {
213     public:
size() const214         size_t size() const { return fSize; }
215 
find(const FACTORY & factory,const SkMatrix & matrix,SkVector * translate) const216         sk_sp<SkVertices> find(const FACTORY& factory, const SkMatrix& matrix,
217                                SkVector* translate) const {
218             for (int i = 0; i < MAX_ENTRIES; ++i) {
219                 if (fEntries[i].fFactory.isCompatible(factory, translate)) {
220                     const SkMatrix& m = fEntries[i].fMatrix;
221                     if (matrix.hasPerspective() || m.hasPerspective()) {
222                         if (matrix != fEntries[i].fMatrix) {
223                             continue;
224                         }
225                     } else if (matrix.getScaleX() != m.getScaleX() ||
226                                matrix.getSkewX() != m.getSkewX() ||
227                                matrix.getScaleY() != m.getScaleY() ||
228                                matrix.getSkewY() != m.getSkewY()) {
229                         continue;
230                     }
231                     return fEntries[i].fVertices;
232                 }
233             }
234             return nullptr;
235         }
236 
add(const SkPath & path,const FACTORY & factory,const SkMatrix & matrix,SkVector * translate)237         sk_sp<SkVertices> add(const SkPath& path, const FACTORY& factory, const SkMatrix& matrix,
238                               SkVector* translate) {
239             sk_sp<SkVertices> vertices = factory.makeVertices(path, matrix, translate);
240             if (!vertices) {
241                 return nullptr;
242             }
243             int i;
244             if (fCount < MAX_ENTRIES) {
245                 i = fCount++;
246             } else {
247                 i = fRandom.nextULessThan(MAX_ENTRIES);
248                 fSize -= fEntries[i].fVertices->approximateSize();
249             }
250             fEntries[i].fFactory = factory;
251             fEntries[i].fVertices = vertices;
252             fEntries[i].fMatrix = matrix;
253             fSize += vertices->approximateSize();
254             return vertices;
255         }
256 
257     private:
258         struct Entry {
259             FACTORY fFactory;
260             sk_sp<SkVertices> fVertices;
261             SkMatrix fMatrix;
262         };
263         Entry fEntries[MAX_ENTRIES];
264         int fCount = 0;
265         size_t fSize = 0;
266         SkRandom fRandom;
267     };
268 
269     Set<AmbientVerticesFactory, 4> fAmbientSet;
270     Set<SpotVerticesFactory, 4> fSpotSet;
271 };
272 
273 /**
274  * A record of shadow vertices stored in SkResourceCache of CachedTessellations for a particular
275  * path. The key represents the path's geometry and not any shadow params.
276  */
277 class CachedTessellationsRec : public SkResourceCache::Rec {
278 public:
CachedTessellationsRec(const SkResourceCache::Key & key,sk_sp<CachedTessellations> tessellations)279     CachedTessellationsRec(const SkResourceCache::Key& key,
280                            sk_sp<CachedTessellations> tessellations)
281             : fTessellations(std::move(tessellations)) {
282         fKey.reset(new uint8_t[key.size()]);
283         memcpy(fKey.get(), &key, key.size());
284     }
285 
getKey() const286     const Key& getKey() const override {
287         return *reinterpret_cast<SkResourceCache::Key*>(fKey.get());
288     }
289 
bytesUsed() const290     size_t bytesUsed() const override { return fTessellations->size(); }
291 
getCategory() const292     const char* getCategory() const override { return "tessellated shadow masks"; }
293 
refTessellations() const294     sk_sp<CachedTessellations> refTessellations() const { return fTessellations; }
295 
296     template <typename FACTORY>
find(const FACTORY & factory,const SkMatrix & matrix,SkVector * translate) const297     sk_sp<SkVertices> find(const FACTORY& factory, const SkMatrix& matrix,
298                            SkVector* translate) const {
299         return fTessellations->find(factory, matrix, translate);
300     }
301 
302 private:
303     std::unique_ptr<uint8_t[]> fKey;
304     sk_sp<CachedTessellations> fTessellations;
305 };
306 
307 /**
308  * Used by FindVisitor to determine whether a cache entry can be reused and if so returns the
309  * vertices and a translation vector. If the CachedTessellations does not contain a suitable
310  * mesh then we inform SkResourceCache to destroy the Rec and we return the CachedTessellations
311  * to the caller. The caller will update it and reinsert it back into the cache.
312  */
313 template <typename FACTORY>
314 struct FindContext {
FindContext__anon33e536640111::FindContext315     FindContext(const SkMatrix* viewMatrix, const FACTORY* factory)
316             : fViewMatrix(viewMatrix), fFactory(factory) {}
317     const SkMatrix* const fViewMatrix;
318     // If this is valid after Find is called then we found the vertices and they should be drawn
319     // with fTranslate applied.
320     sk_sp<SkVertices> fVertices;
321     SkVector fTranslate = {0, 0};
322 
323     // If this is valid after Find then the caller should add the vertices to the tessellation set
324     // and create a new CachedTessellationsRec and insert it into SkResourceCache.
325     sk_sp<CachedTessellations> fTessellationsOnFailure;
326 
327     const FACTORY* fFactory;
328 };
329 
330 /**
331  * Function called by SkResourceCache when a matching cache key is found. The FACTORY and matrix of
332  * the FindContext are used to determine if the vertices are reusable. If so the vertices and
333  * necessary translation vector are set on the FindContext.
334  */
335 template <typename FACTORY>
FindVisitor(const SkResourceCache::Rec & baseRec,void * ctx)336 bool FindVisitor(const SkResourceCache::Rec& baseRec, void* ctx) {
337     FindContext<FACTORY>* findContext = (FindContext<FACTORY>*)ctx;
338     const CachedTessellationsRec& rec = static_cast<const CachedTessellationsRec&>(baseRec);
339     findContext->fVertices =
340             rec.find(*findContext->fFactory, *findContext->fViewMatrix, &findContext->fTranslate);
341     if (findContext->fVertices) {
342         return true;
343     }
344     // We ref the tessellations and let the cache destroy the Rec. Once the tessellations have been
345     // manipulated we will add a new Rec.
346     findContext->fTessellationsOnFailure = rec.refTessellations();
347     return false;
348 }
349 
350 class ShadowedPath {
351 public:
ShadowedPath(const SkPath * path,const SkMatrix * viewMatrix)352     ShadowedPath(const SkPath* path, const SkMatrix* viewMatrix)
353             : fPath(path)
354             , fViewMatrix(viewMatrix)
355 #if SK_SUPPORT_GPU
356             , fShapeForKey(*path, GrStyle::SimpleFill())
357 #endif
358     {}
359 
path() const360     const SkPath& path() const { return *fPath; }
viewMatrix() const361     const SkMatrix& viewMatrix() const { return *fViewMatrix; }
362 #if SK_SUPPORT_GPU
363     /** Negative means the vertices should not be cached for this path. */
keyBytes() const364     int keyBytes() const { return fShapeForKey.unstyledKeySize() * sizeof(uint32_t); }
writeKey(void * key) const365     void writeKey(void* key) const {
366         fShapeForKey.writeUnstyledKey(reinterpret_cast<uint32_t*>(key));
367     }
isRRect(SkRRect * rrect)368     bool isRRect(SkRRect* rrect) { return fShapeForKey.asRRect(rrect, nullptr, nullptr, nullptr); }
369 #else
keyBytes() const370     int keyBytes() const { return -1; }
writeKey(void * key) const371     void writeKey(void* key) const { SkFAIL("Should never be called"); }
isRRect(SkRRect * rrect)372     bool isRRect(SkRRect* rrect) { return false; }
373 #endif
374 
375 private:
376     const SkPath* fPath;
377     const SkMatrix* fViewMatrix;
378 #if SK_SUPPORT_GPU
379     GrShape fShapeForKey;
380 #endif
381 };
382 
383 // This creates a domain of keys in SkResourceCache used by this file.
384 static void* kNamespace;
385 
386 /**
387  * Draws a shadow to 'canvas'. The vertices used to draw the shadow are created by 'factory' unless
388  * they are first found in SkResourceCache.
389  */
390 template <typename FACTORY>
draw_shadow(const FACTORY & factory,std::function<void (const SkVertices *,SkBlendMode,const SkPaint &,SkScalar tx,SkScalar ty)> drawProc,ShadowedPath & path,SkColor color)391     void draw_shadow(const FACTORY& factory,
392                      std::function<void(const SkVertices*, SkBlendMode, const SkPaint&,
393                      SkScalar tx, SkScalar ty)> drawProc, ShadowedPath& path, SkColor color) {
394     FindContext<FACTORY> context(&path.viewMatrix(), &factory);
395 
396     SkResourceCache::Key* key = nullptr;
397     SkAutoSTArray<32 * 4, uint8_t> keyStorage;
398     int keyDataBytes = path.keyBytes();
399     if (keyDataBytes >= 0) {
400         keyStorage.reset(keyDataBytes + sizeof(SkResourceCache::Key));
401         key = new (keyStorage.begin()) SkResourceCache::Key();
402         path.writeKey((uint32_t*)(keyStorage.begin() + sizeof(*key)));
403         key->init(&kNamespace, resource_cache_shared_id(), keyDataBytes);
404         SkResourceCache::Find(*key, FindVisitor<FACTORY>, &context);
405     }
406 
407     sk_sp<SkVertices> vertices;
408     bool foundInCache = SkToBool(context.fVertices);
409     if (foundInCache) {
410         vertices = std::move(context.fVertices);
411     } else {
412         // TODO: handle transforming the path as part of the tessellator
413         if (key) {
414             // Update or initialize a tessellation set and add it to the cache.
415             sk_sp<CachedTessellations> tessellations;
416             if (context.fTessellationsOnFailure) {
417                 tessellations = std::move(context.fTessellationsOnFailure);
418             } else {
419                 tessellations.reset(new CachedTessellations());
420             }
421             vertices = tessellations->add(path.path(), factory, path.viewMatrix(),
422                                           &context.fTranslate);
423             if (!vertices) {
424                 return;
425             }
426             auto rec = new CachedTessellationsRec(*key, std::move(tessellations));
427             SkResourceCache::Add(rec);
428         } else {
429             vertices = factory.makeVertices(path.path(), path.viewMatrix(),
430                                             &context.fTranslate);
431             if (!vertices) {
432                 return;
433             }
434         }
435     }
436 
437     SkPaint paint;
438     // Run the vertex color through a GaussianColorFilter and then modulate the grayscale result of
439     // that against our 'color' param.
440     paint.setColorFilter(SkColorFilter::MakeComposeFilter(
441             SkColorFilter::MakeModeFilter(color, SkBlendMode::kModulate),
442             SkGaussianColorFilter::Make()));
443 
444     drawProc(vertices.get(), SkBlendMode::kModulate, paint,
445              context.fTranslate.fX, context.fTranslate.fY);
446 }
447 }
448 
tilted(const SkPoint3 & zPlaneParams)449 static bool tilted(const SkPoint3& zPlaneParams) {
450     return !SkScalarNearlyZero(zPlaneParams.fX) || !SkScalarNearlyZero(zPlaneParams.fY);
451 }
452 
map(const SkMatrix & m,const SkPoint3 & pt)453 static SkPoint3 map(const SkMatrix& m, const SkPoint3& pt) {
454     SkPoint3 result;
455     m.mapXY(pt.fX, pt.fY, (SkPoint*)&result.fX);
456     result.fZ = pt.fZ;
457     return result;
458 }
459 
compute_render_color(SkColor color,float alpha,bool useTonalColor)460 static SkColor compute_render_color(SkColor color, float alpha, bool useTonalColor) {
461     if (useTonalColor) {
462         SkScalar colorScale;
463         SkScalar tonalAlpha;
464         SkColor4f color4f = SkColor4f::FromColor(color);
465         SkShadowUtils::ComputeTonalColorParams(color4f.fR,
466                                                color4f.fG,
467                                                color4f.fB,
468                                                alpha,
469                                                &colorScale, &tonalAlpha);
470         // After pre-multiplying, we want the alpha to be scaled by tonalAlpha, and
471         // the color scaled by colorScale. This scale factor gives that.
472         SkScalar unPremulScale = colorScale / tonalAlpha;
473 
474         return SkColorSetARGB(tonalAlpha*255.999f, unPremulScale*SkColorGetR(color),
475                               unPremulScale*SkColorGetG(color), unPremulScale*SkColorGetB(color));
476     }
477 
478     return SkColorSetARGB(alpha*SkColorGetA(color), SkColorGetR(color),
479                           SkColorGetG(color), SkColorGetB(color));
480 }
481 
482 // Draw an offset spot shadow and outlining ambient shadow for the given path.
DrawShadow(SkCanvas * canvas,const SkPath & path,const SkPoint3 & zPlaneParams,const SkPoint3 & devLightPos,SkScalar lightRadius,SkScalar ambientAlpha,SkScalar spotAlpha,SkColor color,uint32_t flags)483 void SkShadowUtils::DrawShadow(SkCanvas* canvas, const SkPath& path, const SkPoint3& zPlaneParams,
484                                const SkPoint3& devLightPos, SkScalar lightRadius,
485                                SkScalar ambientAlpha, SkScalar spotAlpha, SkColor color,
486                                uint32_t flags) {
487     SkMatrix inverse;
488     if (!canvas->getTotalMatrix().invert(&inverse)) {
489         return;
490     }
491     SkPoint pt = inverse.mapXY(devLightPos.fX, devLightPos.fY);
492 
493     SkDrawShadowRec rec;
494     rec.fZPlaneParams   = zPlaneParams;
495     rec.fLightPos       = { pt.fX, pt.fY, devLightPos.fZ };
496     rec.fLightRadius    = lightRadius;
497     rec.fAmbientAlpha   = SkScalarToFloat(ambientAlpha);
498     rec.fSpotAlpha      = SkScalarToFloat(spotAlpha);
499     rec.fColor          = color;
500     rec.fFlags          = flags;
501 
502     canvas->private_draw_shadow_rec(path, rec);
503 }
504 
drawShadow(const SkPath & path,const SkDrawShadowRec & rec)505 void SkBaseDevice::drawShadow(const SkPath& path, const SkDrawShadowRec& rec) {
506     auto drawVertsProc = [this](const SkVertices* vertices, SkBlendMode mode, const SkPaint& paint,
507                                 SkScalar tx, SkScalar ty) {
508         SkAutoDeviceCTMRestore adr(this, SkMatrix::Concat(this->ctm(),
509                                                           SkMatrix::MakeTrans(tx, ty)));
510         this->drawVertices(vertices, mode, paint);
511     };
512 
513     SkMatrix viewMatrix = this->ctm();
514     SkAutoDeviceCTMRestore adr(this, SkMatrix::I());
515 
516     ShadowedPath shadowedPath(&path, &viewMatrix);
517 
518     bool tiltZPlane = tilted(rec.fZPlaneParams);
519     bool transparent = SkToBool(rec.fFlags & SkShadowFlags::kTransparentOccluder_ShadowFlag);
520     bool uncached = tiltZPlane || path.isVolatile();
521     bool useTonalColor = SkToBool(rec.fFlags & kTonalColor_ShadowFlag);
522 
523     SkColor color = rec.fColor;
524     SkPoint3 zPlaneParams = rec.fZPlaneParams;
525     SkPoint3 devLightPos = map(viewMatrix, rec.fLightPos);
526     float lightRadius = rec.fLightRadius;
527 
528     float ambientAlpha = rec.fAmbientAlpha;
529     if (ambientAlpha > 0) {
530         ambientAlpha = SkTMin(ambientAlpha, 1.f);
531         SkColor renderColor;
532         if (useTonalColor) {
533             renderColor = compute_render_color(SK_ColorBLACK, ambientAlpha, false);
534         } else {
535             renderColor = compute_render_color(color, ambientAlpha, false);
536         }
537         if (uncached) {
538             sk_sp<SkVertices> vertices = SkShadowTessellator::MakeAmbient(path, viewMatrix,
539                                                                           zPlaneParams,
540                                                                           transparent);
541             if (vertices) {
542                 SkPaint paint;
543                 // Run the vertex color through a GaussianColorFilter and then modulate the
544                 // grayscale result of that against our 'color' param.
545                 paint.setColorFilter(SkColorFilter::MakeComposeFilter(
546                     SkColorFilter::MakeModeFilter(renderColor, SkBlendMode::kModulate),
547                     SkGaussianColorFilter::Make()));
548                 this->drawVertices(vertices.get(), SkBlendMode::kModulate, paint);
549             }
550         } else {
551             AmbientVerticesFactory factory;
552             factory.fOccluderHeight = zPlaneParams.fZ;
553             factory.fTransparent = transparent;
554             if (viewMatrix.hasPerspective()) {
555                 factory.fOffset.set(0, 0);
556             } else {
557                 factory.fOffset.fX = viewMatrix.getTranslateX();
558                 factory.fOffset.fY = viewMatrix.getTranslateY();
559             }
560 
561             draw_shadow(factory, drawVertsProc, shadowedPath, renderColor);
562         }
563     }
564 
565     float spotAlpha = rec.fSpotAlpha;
566     if (spotAlpha > 0) {
567         spotAlpha = SkTMin(spotAlpha, 1.f);
568         SkColor renderColor = compute_render_color(color, spotAlpha, useTonalColor);
569         if (uncached) {
570             sk_sp<SkVertices> vertices = SkShadowTessellator::MakeSpot(path, viewMatrix,
571                                                                        zPlaneParams,
572                                                                        devLightPos, lightRadius,
573                                                                        transparent);
574             if (vertices) {
575                 SkPaint paint;
576                 // Run the vertex color through a GaussianColorFilter and then modulate the
577                 // grayscale result of that against our 'color' param.
578                 paint.setColorFilter(SkColorFilter::MakeComposeFilter(
579                     SkColorFilter::MakeModeFilter(renderColor, SkBlendMode::kModulate),
580                     SkGaussianColorFilter::Make()));
581                 this->drawVertices(vertices.get(), SkBlendMode::kModulate, paint);
582             }
583         } else {
584             SpotVerticesFactory factory;
585             SkScalar occluderHeight = zPlaneParams.fZ;
586             float zRatio = SkTPin(occluderHeight / (devLightPos.fZ - occluderHeight), 0.0f, 0.95f);
587             SkScalar radius = lightRadius * zRatio;
588 
589             // Compute the scale and translation for the spot shadow.
590             SkScalar scale = devLightPos.fZ / (devLightPos.fZ - occluderHeight);
591             SkPoint center = SkPoint::Make(path.getBounds().centerX(), path.getBounds().centerY());
592             factory.fLocalCenter = center;
593             viewMatrix.mapPoints(&center, 1);
594             factory.fOffset = SkVector::Make(zRatio * (center.fX - devLightPos.fX),
595                                              zRatio * (center.fY - devLightPos.fY));
596             factory.fOccluderHeight = occluderHeight;
597             factory.fDevLightPos = devLightPos;
598             factory.fLightRadius = lightRadius;
599             SkRect devBounds;
600             viewMatrix.mapRect(&devBounds, path.getBounds());
601             if (transparent ||
602                 SkTAbs(factory.fOffset.fX) > 0.5f*devBounds.width() ||
603                 SkTAbs(factory.fOffset.fY) > 0.5f*devBounds.height()) {
604                 // if the translation of the shadow is big enough we're going to end up
605                 // filling the entire umbra, so we can treat these as all the same
606                 factory.fOccluderType = SpotVerticesFactory::OccluderType::kTransparent;
607             } else if (factory.fOffset.length()*scale + scale < radius) {
608                 // if we don't translate more than the blur distance, can assume umbra is covered
609                 factory.fOccluderType = SpotVerticesFactory::OccluderType::kOpaqueNoUmbra;
610             } else {
611                 factory.fOccluderType = SpotVerticesFactory::OccluderType::kOpaquePartialUmbra;
612             }
613             // need to add this after we classify the shadow
614             factory.fOffset.fX += viewMatrix.getTranslateX();
615             factory.fOffset.fY += viewMatrix.getTranslateY();
616 #ifdef DEBUG_SHADOW_CHECKS
617             switch (factory.fOccluderType) {
618                 case SpotVerticesFactory::OccluderType::kTransparent:
619                     color = 0xFFD2B48C;  // tan for transparent
620                     break;
621                 case SpotVerticesFactory::OccluderType::kOpaquePartialUmbra:
622                     color = 0xFFFFA500;   // orange for opaque
623                     break;
624                 case SpotVerticesFactory::OccluderType::kOpaqueNoUmbra:
625                     color = 0xFFE5E500;  // corn yellow for covered
626                     break;
627             }
628 #endif
629             draw_shadow(factory, drawVertsProc, shadowedPath, renderColor);
630         }
631     }
632 }
633