/* * Copyright 2017 Google Inc. * * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ #include "SkShadowUtils.h" #include "SkCanvas.h" #include "SkColorFilter.h" #include "SkColorData.h" #include "SkDevice.h" #include "SkDrawShadowInfo.h" #include "SkPath.h" #include "SkPM4f.h" #include "SkRandom.h" #include "SkRasterPipeline.h" #include "SkResourceCache.h" #include "SkShadowTessellator.h" #include "SkString.h" #include "SkTLazy.h" #include "SkVertices.h" #if SK_SUPPORT_GPU #include "GrShape.h" #include "effects/GrBlurredEdgeFragmentProcessor.h" #endif /** * Gaussian color filter -- produces a Gaussian ramp based on the color's B value, * then blends with the color's G value. * Final result is black with alpha of Gaussian(B)*G. * The assumption is that the original color's alpha is 1. */ class SkGaussianColorFilter : public SkColorFilter { public: static sk_sp<SkColorFilter> Make() { return sk_sp<SkColorFilter>(new SkGaussianColorFilter); } #if SK_SUPPORT_GPU std::unique_ptr<GrFragmentProcessor> asFragmentProcessor( GrContext*, const GrColorSpaceInfo&) const override; #endif SK_TO_STRING_OVERRIDE() SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkGaussianColorFilter) protected: void flatten(SkWriteBuffer&) const override {} void onAppendStages(SkRasterPipeline* pipeline, SkColorSpace* dstCS, SkArenaAlloc* alloc, bool shaderIsOpaque) const override { pipeline->append(SkRasterPipeline::gauss_a_to_rgba); } private: SkGaussianColorFilter() : INHERITED() {} typedef SkColorFilter INHERITED; }; sk_sp<SkFlattenable> SkGaussianColorFilter::CreateProc(SkReadBuffer&) { return Make(); } #ifndef SK_IGNORE_TO_STRING void SkGaussianColorFilter::toString(SkString* str) const { str->append("SkGaussianColorFilter "); } #endif #if SK_SUPPORT_GPU std::unique_ptr<GrFragmentProcessor> SkGaussianColorFilter::asFragmentProcessor( GrContext*, const GrColorSpaceInfo&) const { return GrBlurredEdgeFragmentProcessor::Make(GrBlurredEdgeFragmentProcessor::Mode::kGaussian); } #endif /////////////////////////////////////////////////////////////////////////////////////////////////// namespace { uint64_t resource_cache_shared_id() { return 0x2020776f64616873llu; // 'shadow ' } /** Factory for an ambient shadow mesh with particular shadow properties. */ struct AmbientVerticesFactory { SkScalar fOccluderHeight = SK_ScalarNaN; // NaN so that isCompatible will fail until init'ed. bool fTransparent; SkVector fOffset; bool isCompatible(const AmbientVerticesFactory& that, SkVector* translate) const { if (fOccluderHeight != that.fOccluderHeight || fTransparent != that.fTransparent) { return false; } *translate = that.fOffset; return true; } sk_sp<SkVertices> makeVertices(const SkPath& path, const SkMatrix& ctm, SkVector* translate) const { SkPoint3 zParams = SkPoint3::Make(0, 0, fOccluderHeight); // pick a canonical place to generate shadow SkMatrix noTrans(ctm); if (!ctm.hasPerspective()) { noTrans[SkMatrix::kMTransX] = 0; noTrans[SkMatrix::kMTransY] = 0; } *translate = fOffset; return SkShadowTessellator::MakeAmbient(path, noTrans, zParams, fTransparent); } }; /** Factory for an spot shadow mesh with particular shadow properties. */ struct SpotVerticesFactory { enum class OccluderType { // The umbra cannot be dropped out because either the occluder is not opaque, // or the center of the umbra is visible. kTransparent, // The umbra can be dropped where it is occluded. kOpaquePartialUmbra, // It is known that the entire umbra is occluded. kOpaqueNoUmbra }; SkVector fOffset; SkPoint fLocalCenter; SkScalar fOccluderHeight = SK_ScalarNaN; // NaN so that isCompatible will fail until init'ed. SkPoint3 fDevLightPos; SkScalar fLightRadius; OccluderType fOccluderType; bool isCompatible(const SpotVerticesFactory& that, SkVector* translate) const { if (fOccluderHeight != that.fOccluderHeight || fDevLightPos.fZ != that.fDevLightPos.fZ || fLightRadius != that.fLightRadius || fOccluderType != that.fOccluderType) { return false; } switch (fOccluderType) { case OccluderType::kTransparent: case OccluderType::kOpaqueNoUmbra: // 'this' and 'that' will either both have no umbra removed or both have all the // umbra removed. *translate = that.fOffset; return true; case OccluderType::kOpaquePartialUmbra: // In this case we partially remove the umbra differently for 'this' and 'that' // if the offsets don't match. if (fOffset == that.fOffset) { translate->set(0, 0); return true; } return false; } SK_ABORT("Uninitialized occluder type?"); return false; } sk_sp<SkVertices> makeVertices(const SkPath& path, const SkMatrix& ctm, SkVector* translate) const { bool transparent = OccluderType::kTransparent == fOccluderType; SkPoint3 zParams = SkPoint3::Make(0, 0, fOccluderHeight); if (ctm.hasPerspective() || OccluderType::kOpaquePartialUmbra == fOccluderType) { translate->set(0, 0); return SkShadowTessellator::MakeSpot(path, ctm, zParams, fDevLightPos, fLightRadius, transparent); } else { // pick a canonical place to generate shadow, with light centered over path SkMatrix noTrans(ctm); noTrans[SkMatrix::kMTransX] = 0; noTrans[SkMatrix::kMTransY] = 0; SkPoint devCenter(fLocalCenter); noTrans.mapPoints(&devCenter, 1); SkPoint3 centerLightPos = SkPoint3::Make(devCenter.fX, devCenter.fY, fDevLightPos.fZ); *translate = fOffset; return SkShadowTessellator::MakeSpot(path, noTrans, zParams, centerLightPos, fLightRadius, transparent); } } }; /** * This manages a set of tessellations for a given shape in the cache. Because SkResourceCache * records are immutable this is not itself a Rec. When we need to update it we return this on * the FindVisitor and let the cache destroy the Rec. We'll update the tessellations and then add * a new Rec with an adjusted size for any deletions/additions. */ class CachedTessellations : public SkRefCnt { public: size_t size() const { return fAmbientSet.size() + fSpotSet.size(); } sk_sp<SkVertices> find(const AmbientVerticesFactory& ambient, const SkMatrix& matrix, SkVector* translate) const { return fAmbientSet.find(ambient, matrix, translate); } sk_sp<SkVertices> add(const SkPath& devPath, const AmbientVerticesFactory& ambient, const SkMatrix& matrix, SkVector* translate) { return fAmbientSet.add(devPath, ambient, matrix, translate); } sk_sp<SkVertices> find(const SpotVerticesFactory& spot, const SkMatrix& matrix, SkVector* translate) const { return fSpotSet.find(spot, matrix, translate); } sk_sp<SkVertices> add(const SkPath& devPath, const SpotVerticesFactory& spot, const SkMatrix& matrix, SkVector* translate) { return fSpotSet.add(devPath, spot, matrix, translate); } private: template <typename FACTORY, int MAX_ENTRIES> class Set { public: size_t size() const { return fSize; } sk_sp<SkVertices> find(const FACTORY& factory, const SkMatrix& matrix, SkVector* translate) const { for (int i = 0; i < MAX_ENTRIES; ++i) { if (fEntries[i].fFactory.isCompatible(factory, translate)) { const SkMatrix& m = fEntries[i].fMatrix; if (matrix.hasPerspective() || m.hasPerspective()) { if (matrix != fEntries[i].fMatrix) { continue; } } else if (matrix.getScaleX() != m.getScaleX() || matrix.getSkewX() != m.getSkewX() || matrix.getScaleY() != m.getScaleY() || matrix.getSkewY() != m.getSkewY()) { continue; } return fEntries[i].fVertices; } } return nullptr; } sk_sp<SkVertices> add(const SkPath& path, const FACTORY& factory, const SkMatrix& matrix, SkVector* translate) { sk_sp<SkVertices> vertices = factory.makeVertices(path, matrix, translate); if (!vertices) { return nullptr; } int i; if (fCount < MAX_ENTRIES) { i = fCount++; } else { i = fRandom.nextULessThan(MAX_ENTRIES); fSize -= fEntries[i].fVertices->approximateSize(); } fEntries[i].fFactory = factory; fEntries[i].fVertices = vertices; fEntries[i].fMatrix = matrix; fSize += vertices->approximateSize(); return vertices; } private: struct Entry { FACTORY fFactory; sk_sp<SkVertices> fVertices; SkMatrix fMatrix; }; Entry fEntries[MAX_ENTRIES]; int fCount = 0; size_t fSize = 0; SkRandom fRandom; }; Set<AmbientVerticesFactory, 4> fAmbientSet; Set<SpotVerticesFactory, 4> fSpotSet; }; /** * A record of shadow vertices stored in SkResourceCache of CachedTessellations for a particular * path. The key represents the path's geometry and not any shadow params. */ class CachedTessellationsRec : public SkResourceCache::Rec { public: CachedTessellationsRec(const SkResourceCache::Key& key, sk_sp<CachedTessellations> tessellations) : fTessellations(std::move(tessellations)) { fKey.reset(new uint8_t[key.size()]); memcpy(fKey.get(), &key, key.size()); } const Key& getKey() const override { return *reinterpret_cast<SkResourceCache::Key*>(fKey.get()); } size_t bytesUsed() const override { return fTessellations->size(); } const char* getCategory() const override { return "tessellated shadow masks"; } sk_sp<CachedTessellations> refTessellations() const { return fTessellations; } template <typename FACTORY> sk_sp<SkVertices> find(const FACTORY& factory, const SkMatrix& matrix, SkVector* translate) const { return fTessellations->find(factory, matrix, translate); } private: std::unique_ptr<uint8_t[]> fKey; sk_sp<CachedTessellations> fTessellations; }; /** * Used by FindVisitor to determine whether a cache entry can be reused and if so returns the * vertices and a translation vector. If the CachedTessellations does not contain a suitable * mesh then we inform SkResourceCache to destroy the Rec and we return the CachedTessellations * to the caller. The caller will update it and reinsert it back into the cache. */ template <typename FACTORY> struct FindContext { FindContext(const SkMatrix* viewMatrix, const FACTORY* factory) : fViewMatrix(viewMatrix), fFactory(factory) {} const SkMatrix* const fViewMatrix; // If this is valid after Find is called then we found the vertices and they should be drawn // with fTranslate applied. sk_sp<SkVertices> fVertices; SkVector fTranslate = {0, 0}; // If this is valid after Find then the caller should add the vertices to the tessellation set // and create a new CachedTessellationsRec and insert it into SkResourceCache. sk_sp<CachedTessellations> fTessellationsOnFailure; const FACTORY* fFactory; }; /** * Function called by SkResourceCache when a matching cache key is found. The FACTORY and matrix of * the FindContext are used to determine if the vertices are reusable. If so the vertices and * necessary translation vector are set on the FindContext. */ template <typename FACTORY> bool FindVisitor(const SkResourceCache::Rec& baseRec, void* ctx) { FindContext<FACTORY>* findContext = (FindContext<FACTORY>*)ctx; const CachedTessellationsRec& rec = static_cast<const CachedTessellationsRec&>(baseRec); findContext->fVertices = rec.find(*findContext->fFactory, *findContext->fViewMatrix, &findContext->fTranslate); if (findContext->fVertices) { return true; } // We ref the tessellations and let the cache destroy the Rec. Once the tessellations have been // manipulated we will add a new Rec. findContext->fTessellationsOnFailure = rec.refTessellations(); return false; } class ShadowedPath { public: ShadowedPath(const SkPath* path, const SkMatrix* viewMatrix) : fPath(path) , fViewMatrix(viewMatrix) #if SK_SUPPORT_GPU , fShapeForKey(*path, GrStyle::SimpleFill()) #endif {} const SkPath& path() const { return *fPath; } const SkMatrix& viewMatrix() const { return *fViewMatrix; } #if SK_SUPPORT_GPU /** Negative means the vertices should not be cached for this path. */ int keyBytes() const { return fShapeForKey.unstyledKeySize() * sizeof(uint32_t); } void writeKey(void* key) const { fShapeForKey.writeUnstyledKey(reinterpret_cast<uint32_t*>(key)); } bool isRRect(SkRRect* rrect) { return fShapeForKey.asRRect(rrect, nullptr, nullptr, nullptr); } #else int keyBytes() const { return -1; } void writeKey(void* key) const { SK_ABORT("Should never be called"); } bool isRRect(SkRRect* rrect) { return false; } #endif private: const SkPath* fPath; const SkMatrix* fViewMatrix; #if SK_SUPPORT_GPU GrShape fShapeForKey; #endif }; // This creates a domain of keys in SkResourceCache used by this file. static void* kNamespace; /** * Draws a shadow to 'canvas'. The vertices used to draw the shadow are created by 'factory' unless * they are first found in SkResourceCache. */ template <typename FACTORY> void draw_shadow(const FACTORY& factory, std::function<void(const SkVertices*, SkBlendMode, const SkPaint&, SkScalar tx, SkScalar ty)> drawProc, ShadowedPath& path, SkColor color) { FindContext<FACTORY> context(&path.viewMatrix(), &factory); SkResourceCache::Key* key = nullptr; SkAutoSTArray<32 * 4, uint8_t> keyStorage; int keyDataBytes = path.keyBytes(); if (keyDataBytes >= 0) { keyStorage.reset(keyDataBytes + sizeof(SkResourceCache::Key)); key = new (keyStorage.begin()) SkResourceCache::Key(); path.writeKey((uint32_t*)(keyStorage.begin() + sizeof(*key))); key->init(&kNamespace, resource_cache_shared_id(), keyDataBytes); SkResourceCache::Find(*key, FindVisitor<FACTORY>, &context); } sk_sp<SkVertices> vertices; bool foundInCache = SkToBool(context.fVertices); if (foundInCache) { vertices = std::move(context.fVertices); } else { // TODO: handle transforming the path as part of the tessellator if (key) { // Update or initialize a tessellation set and add it to the cache. sk_sp<CachedTessellations> tessellations; if (context.fTessellationsOnFailure) { tessellations = std::move(context.fTessellationsOnFailure); } else { tessellations.reset(new CachedTessellations()); } vertices = tessellations->add(path.path(), factory, path.viewMatrix(), &context.fTranslate); if (!vertices) { return; } auto rec = new CachedTessellationsRec(*key, std::move(tessellations)); SkResourceCache::Add(rec); } else { vertices = factory.makeVertices(path.path(), path.viewMatrix(), &context.fTranslate); if (!vertices) { return; } } } SkPaint paint; // Run the vertex color through a GaussianColorFilter and then modulate the grayscale result of // that against our 'color' param. paint.setColorFilter(SkColorFilter::MakeComposeFilter( SkColorFilter::MakeModeFilter(color, SkBlendMode::kModulate), SkGaussianColorFilter::Make())); drawProc(vertices.get(), SkBlendMode::kModulate, paint, context.fTranslate.fX, context.fTranslate.fY); } } static bool tilted(const SkPoint3& zPlaneParams) { return !SkScalarNearlyZero(zPlaneParams.fX) || !SkScalarNearlyZero(zPlaneParams.fY); } static SkPoint3 map(const SkMatrix& m, const SkPoint3& pt) { SkPoint3 result; m.mapXY(pt.fX, pt.fY, (SkPoint*)&result.fX); result.fZ = pt.fZ; return result; } void SkShadowUtils::ComputeTonalColors(SkColor inAmbientColor, SkColor inSpotColor, SkColor* outAmbientColor, SkColor* outSpotColor) { // For tonal color we only compute color values for the spot shadow. // The ambient shadow is greyscale only. // Ambient *outAmbientColor = SkColorSetARGB(SkColorGetA(inAmbientColor), 0, 0, 0); // Spot int spotR = SkColorGetR(inSpotColor); int spotG = SkColorGetG(inSpotColor); int spotB = SkColorGetB(inSpotColor); int max = SkTMax(SkTMax(spotR, spotG), spotB); int min = SkTMin(SkTMin(spotR, spotG), spotB); SkScalar luminance = 0.5f*(max + min)/255.f; SkScalar origA = SkColorGetA(inSpotColor)/255.f; // We compute a color alpha value based on the luminance of the color, scaled by an // adjusted alpha value. We want the following properties to match the UX examples // (assuming a = 0.25) and to ensure that we have reasonable results when the color // is black and/or the alpha is 0: // f(0, a) = 0 // f(luminance, 0) = 0 // f(1, 0.25) = .5 // f(0.5, 0.25) = .4 // f(1, 1) = 1 // The following functions match this as closely as possible. SkScalar alphaAdjust = (2.6f + (-2.66667f + 1.06667f*origA)*origA)*origA; SkScalar colorAlpha = (3.544762f + (-4.891428f + 2.3466f*luminance)*luminance)*luminance; colorAlpha = SkTPin(alphaAdjust*colorAlpha, 0.0f, 1.0f); // Similarly, we set the greyscale alpha based on luminance and alpha so that // f(0, a) = a // f(luminance, 0) = 0 // f(1, 0.25) = 0.15 SkScalar greyscaleAlpha = SkTPin(origA*(1 - 0.4f*luminance), 0.0f, 1.0f); // The final color we want to emulate is generated by rendering a color shadow (C_rgb) using an // alpha computed from the color's luminance (C_a), and then a black shadow with alpha (S_a) // which is an adjusted value of 'a'. Assuming SrcOver, a background color of B_rgb, and // ignoring edge falloff, this becomes // // (C_a - S_a*C_a)*C_rgb + (1 - (S_a + C_a - S_a*C_a))*B_rgb // // Assuming premultiplied alpha, this means we scale the color by (C_a - S_a*C_a) and // set the alpha to (S_a + C_a - S_a*C_a). SkScalar colorScale = colorAlpha*(SK_Scalar1 - greyscaleAlpha); SkScalar tonalAlpha = colorScale + greyscaleAlpha; SkScalar unPremulScale = colorScale / tonalAlpha; *outSpotColor = SkColorSetARGB(tonalAlpha*255.999f, unPremulScale*spotR, unPremulScale*spotG, unPremulScale*spotB); } // Draw an offset spot shadow and outlining ambient shadow for the given path. void SkShadowUtils::DrawShadow(SkCanvas* canvas, const SkPath& path, const SkPoint3& zPlaneParams, const SkPoint3& devLightPos, SkScalar lightRadius, SkColor ambientColor, SkColor spotColor, uint32_t flags) { SkMatrix inverse; if (!canvas->getTotalMatrix().invert(&inverse)) { return; } SkPoint pt = inverse.mapXY(devLightPos.fX, devLightPos.fY); SkDrawShadowRec rec; rec.fZPlaneParams = zPlaneParams; rec.fLightPos = { pt.fX, pt.fY, devLightPos.fZ }; rec.fLightRadius = lightRadius; rec.fAmbientColor = ambientColor; rec.fSpotColor = spotColor; rec.fFlags = flags; canvas->private_draw_shadow_rec(path, rec); } void SkBaseDevice::drawShadow(const SkPath& path, const SkDrawShadowRec& rec) { auto drawVertsProc = [this](const SkVertices* vertices, SkBlendMode mode, const SkPaint& paint, SkScalar tx, SkScalar ty) { SkAutoDeviceCTMRestore adr(this, SkMatrix::Concat(this->ctm(), SkMatrix::MakeTrans(tx, ty))); this->drawVertices(vertices, mode, paint); }; SkMatrix viewMatrix = this->ctm(); SkAutoDeviceCTMRestore adr(this, SkMatrix::I()); ShadowedPath shadowedPath(&path, &viewMatrix); bool tiltZPlane = tilted(rec.fZPlaneParams); bool transparent = SkToBool(rec.fFlags & SkShadowFlags::kTransparentOccluder_ShadowFlag); bool uncached = tiltZPlane || path.isVolatile(); SkPoint3 zPlaneParams = rec.fZPlaneParams; SkPoint3 devLightPos = map(viewMatrix, rec.fLightPos); float lightRadius = rec.fLightRadius; if (SkColorGetA(rec.fAmbientColor) > 0) { if (uncached) { sk_sp<SkVertices> vertices = SkShadowTessellator::MakeAmbient(path, viewMatrix, zPlaneParams, transparent); if (vertices) { SkPaint paint; // Run the vertex color through a GaussianColorFilter and then modulate the // grayscale result of that against our 'color' param. paint.setColorFilter(SkColorFilter::MakeComposeFilter( SkColorFilter::MakeModeFilter(rec.fAmbientColor, SkBlendMode::kModulate), SkGaussianColorFilter::Make())); this->drawVertices(vertices.get(), SkBlendMode::kModulate, paint); } } else { AmbientVerticesFactory factory; factory.fOccluderHeight = zPlaneParams.fZ; factory.fTransparent = transparent; if (viewMatrix.hasPerspective()) { factory.fOffset.set(0, 0); } else { factory.fOffset.fX = viewMatrix.getTranslateX(); factory.fOffset.fY = viewMatrix.getTranslateY(); } draw_shadow(factory, drawVertsProc, shadowedPath, rec.fAmbientColor); } } if (SkColorGetA(rec.fSpotColor) > 0) { if (uncached) { sk_sp<SkVertices> vertices = SkShadowTessellator::MakeSpot(path, viewMatrix, zPlaneParams, devLightPos, lightRadius, transparent); if (vertices) { SkPaint paint; // Run the vertex color through a GaussianColorFilter and then modulate the // grayscale result of that against our 'color' param. paint.setColorFilter(SkColorFilter::MakeComposeFilter( SkColorFilter::MakeModeFilter(rec.fSpotColor, SkBlendMode::kModulate), SkGaussianColorFilter::Make())); this->drawVertices(vertices.get(), SkBlendMode::kModulate, paint); } } else { SpotVerticesFactory factory; SkScalar occluderHeight = zPlaneParams.fZ; float zRatio = SkTPin(occluderHeight / (devLightPos.fZ - occluderHeight), 0.0f, 0.95f); SkScalar radius = lightRadius * zRatio; // Compute the scale and translation for the spot shadow. SkScalar scale = devLightPos.fZ / (devLightPos.fZ - occluderHeight); SkPoint center = SkPoint::Make(path.getBounds().centerX(), path.getBounds().centerY()); factory.fLocalCenter = center; viewMatrix.mapPoints(¢er, 1); factory.fOffset = SkVector::Make(zRatio * (center.fX - devLightPos.fX), zRatio * (center.fY - devLightPos.fY)); factory.fOccluderHeight = occluderHeight; factory.fDevLightPos = devLightPos; factory.fLightRadius = lightRadius; SkRect devBounds; viewMatrix.mapRect(&devBounds, path.getBounds()); if (transparent || SkTAbs(factory.fOffset.fX) > 0.5f*devBounds.width() || SkTAbs(factory.fOffset.fY) > 0.5f*devBounds.height()) { // if the translation of the shadow is big enough we're going to end up // filling the entire umbra, so we can treat these as all the same factory.fOccluderType = SpotVerticesFactory::OccluderType::kTransparent; } else if (factory.fOffset.length()*scale + scale < radius) { // if we don't translate more than the blur distance, can assume umbra is covered factory.fOccluderType = SpotVerticesFactory::OccluderType::kOpaqueNoUmbra; } else { factory.fOccluderType = SpotVerticesFactory::OccluderType::kOpaquePartialUmbra; } // need to add this after we classify the shadow factory.fOffset.fX += viewMatrix.getTranslateX(); factory.fOffset.fY += viewMatrix.getTranslateY(); #ifdef DEBUG_SHADOW_CHECKS switch (factory.fOccluderType) { case SpotVerticesFactory::OccluderType::kTransparent: color = 0xFFD2B48C; // tan for transparent break; case SpotVerticesFactory::OccluderType::kOpaquePartialUmbra: color = 0xFFFFA500; // orange for opaque break; case SpotVerticesFactory::OccluderType::kOpaqueNoUmbra: color = 0xFFE5E500; // corn yellow for covered break; } #endif draw_shadow(factory, drawVertsProc, shadowedPath, rec.fSpotColor); } } }