/*
* 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 "SkPath.h"
#include "SkRandom.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
#include "../../src/effects/shadows/SkAmbientShadowMaskFilter.h"
#include "../../src/effects/shadows/SkSpotShadowMaskFilter.h"
/**
* 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 SK_API SkGaussianColorFilter : public SkColorFilter {
public:
static sk_sp<SkColorFilter> Make() {
return sk_sp<SkColorFilter>(new SkGaussianColorFilter);
}
void filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const override;
#if SK_SUPPORT_GPU
sk_sp<GrFragmentProcessor> asFragmentProcessor(GrContext*, SkColorSpace*) const override;
#endif
SK_TO_STRING_OVERRIDE()
SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkGaussianColorFilter)
protected:
void flatten(SkWriteBuffer&) const override {}
private:
SkGaussianColorFilter() : INHERITED() {}
typedef SkColorFilter INHERITED;
};
void SkGaussianColorFilter::filterSpan(const SkPMColor src[], int count, SkPMColor dst[]) const {
for (int i = 0; i < count; ++i) {
SkPMColor c = src[i];
SkScalar factor = SK_Scalar1 - SkGetPackedB32(c) / 255.f;
factor = SkScalarExp(-factor * factor * 4) - 0.018f;
SkScalar a = factor * SkGetPackedG32(c);
dst[i] = SkPackARGB32(a, a, a, a);
}
}
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
sk_sp<GrFragmentProcessor> SkGaussianColorFilter::asFragmentProcessor(GrContext*,
SkColorSpace*) const {
return GrBlurredEdgeFP::Make(GrBlurredEdgeFP::kGaussian_Mode);
}
#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.
SkScalar fAmbientAlpha;
bool fTransparent;
bool isCompatible(const AmbientVerticesFactory& that, SkVector* translate) const {
if (fOccluderHeight != that.fOccluderHeight || fAmbientAlpha != that.fAmbientAlpha ||
fTransparent != that.fTransparent) {
return false;
}
translate->set(0, 0);
return true;
}
sk_sp<SkVertices> makeVertices(const SkPath& path, const SkMatrix& ctm) const {
SkScalar z = fOccluderHeight;
return SkShadowTessellator::MakeAmbient(path, ctm,
[z](SkScalar, SkScalar) { return z; },
fAmbientAlpha, fTransparent);
}
};
/** Factory for an spot shadow mesh with particular shadow properties. */
struct SpotVerticesFactory {
enum class OccluderType {
// The umbra cannot be dropped out because the occluder is not opaque.
kTransparent,
// The umbra can be dropped where it is occluded.
kOpaque,
// It is known that the entire umbra is occluded.
kOpaqueCoversUmbra
};
SkVector fOffset;
SkScalar fOccluderHeight = SK_ScalarNaN; // NaN so that isCompatible will fail until init'ed.
SkPoint3 fDevLightPos;
SkScalar fLightRadius;
SkScalar fSpotAlpha;
OccluderType fOccluderType;
bool isCompatible(const SpotVerticesFactory& that, SkVector* translate) const {
if (fOccluderHeight != that.fOccluderHeight || fDevLightPos.fZ != that.fDevLightPos.fZ ||
fLightRadius != that.fLightRadius || fSpotAlpha != that.fSpotAlpha ||
fOccluderType != that.fOccluderType) {
return false;
}
switch (fOccluderType) {
case OccluderType::kTransparent:
case OccluderType::kOpaqueCoversUmbra:
// 'this' and 'that' will either both have no umbra removed or both have all the
// umbra removed.
*translate = that.fOffset - fOffset;
return true;
case OccluderType::kOpaque:
// 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;
}
SkFAIL("Uninitialized occluder type?");
return false;
}
sk_sp<SkVertices> makeVertices(const SkPath& path, const SkMatrix& ctm) const {
bool transparent = OccluderType::kTransparent == fOccluderType;
SkScalar z = fOccluderHeight;
return SkShadowTessellator::MakeSpot(path, ctm,
[z](SkScalar, SkScalar) -> SkScalar { return z; },
fDevLightPos, fLightRadius,
fSpotAlpha, 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 destory 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) {
return fAmbientSet.add(devPath, ambient, matrix);
}
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) {
return fSpotSet.add(devPath, spot, matrix);
}
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;
}
*translate += SkVector{matrix.getTranslateX() - m.getTranslateX(),
matrix.getTranslateY() - m.getTranslateY()};
return fEntries[i].fVertices;
}
}
return nullptr;
}
sk_sp<SkVertices> add(const SkPath& path, const FACTORY& factory, const SkMatrix& matrix) {
sk_sp<SkVertices> vertices = factory.makeVertices(path, matrix);
if (!vertices) {
return nullptr;
}
int i;
if (fCount < MAX_ENTRIES) {
i = fCount++;
} else {
i = gRandom.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;
};
Set<AmbientVerticesFactory, 4> fAmbientSet;
Set<SpotVerticesFactory, 4> fSpotSet;
static SkRandom gRandom;
};
SkRandom CachedTessellations::gRandom;
/**
* 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 { SkFAIL("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, SkCanvas* canvas, ShadowedPath& path, SkColor color,
SkResourceCache* cache) {
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);
if (cache) {
cache->find(*key, FindVisitor<FACTORY>, &context);
} else {
SkResourceCache::Find(*key, FindVisitor<FACTORY>, &context);
}
}
sk_sp<SkVertices> vertices;
const SkVector* translate;
static constexpr SkVector kZeroTranslate = {0, 0};
bool foundInCache = SkToBool(context.fVertices);
if (foundInCache) {
vertices = std::move(context.fVertices);
translate = &context.fTranslate;
} 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());
if (!vertices) {
return;
}
auto rec = new CachedTessellationsRec(*key, std::move(tessellations));
if (cache) {
cache->add(rec);
} else {
SkResourceCache::Add(rec);
}
} else {
vertices = factory.makeVertices(path.path(), path.viewMatrix());
if (!vertices) {
return;
}
}
translate = &kZeroTranslate;
}
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()));
if (translate->fX || translate->fY) {
canvas->save();
canvas->translate(translate->fX, translate->fY);
}
canvas->drawVertices(vertices, SkBlendMode::kModulate, paint);
if (translate->fX || translate->fY) {
canvas->restore();
}
}
}
// Draw an offset spot shadow and outlining ambient shadow for the given path.
void SkShadowUtils::DrawShadow(SkCanvas* canvas, const SkPath& path, SkScalar occluderHeight,
const SkPoint3& devLightPos, SkScalar lightRadius,
SkScalar ambientAlpha, SkScalar spotAlpha, SkColor color,
uint32_t flags, SkResourceCache* cache) {
SkAutoCanvasRestore acr(canvas, true);
SkMatrix viewMatrix = canvas->getTotalMatrix();
// try circular fast path
SkRect rect;
if (viewMatrix.isSimilarity() &&
path.isOval(&rect) && rect.width() == rect.height()) {
SkPaint newPaint;
newPaint.setColor(color);
if (ambientAlpha > 0) {
newPaint.setMaskFilter(SkAmbientShadowMaskFilter::Make(occluderHeight, ambientAlpha,
flags));
canvas->drawPath(path, newPaint);
}
if (spotAlpha > 0) {
newPaint.setMaskFilter(SkSpotShadowMaskFilter::Make(occluderHeight, devLightPos,
lightRadius, spotAlpha, flags));
canvas->drawPath(path, newPaint);
}
return;
}
canvas->resetMatrix();
ShadowedPath shadowedPath(&path, &viewMatrix);
bool transparent = SkToBool(flags & SkShadowFlags::kTransparentOccluder_ShadowFlag);
if (ambientAlpha > 0) {
ambientAlpha = SkTMin(ambientAlpha, 1.f);
AmbientVerticesFactory factory;
factory.fOccluderHeight = occluderHeight;
factory.fAmbientAlpha = ambientAlpha;
factory.fTransparent = transparent;
draw_shadow(factory, canvas, shadowedPath, color, cache);
}
if (spotAlpha > 0) {
spotAlpha = SkTMin(spotAlpha, 1.f);
SpotVerticesFactory factory;
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());
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;
factory.fSpotAlpha = spotAlpha;
SkRRect rrect;
if (transparent) {
factory.fOccluderType = SpotVerticesFactory::OccluderType::kTransparent;
} else {
factory.fOccluderType = SpotVerticesFactory::OccluderType::kOpaque;
if (shadowedPath.isRRect(&rrect)) {
SkRRect devRRect;
if (rrect.transform(viewMatrix, &devRRect)) {
SkScalar s = 1.f - scale;
SkScalar w = devRRect.width();
SkScalar h = devRRect.height();
SkScalar hw = w / 2.f;
SkScalar hh = h / 2.f;
SkScalar umbraInsetX = s * hw + radius;
SkScalar umbraInsetY = s * hh + radius;
// The umbra is inset by radius along the diagonal, so adjust for that.
SkScalar d = 1.f / SkScalarSqrt(hw * hw + hh * hh);
umbraInsetX *= hw * d;
umbraInsetY *= hh * d;
if (umbraInsetX > hw || umbraInsetY > hh) {
// There is no umbra to occlude.
factory.fOccluderType = SpotVerticesFactory::OccluderType::kTransparent;
} else if (fabsf(factory.fOffset.fX) < umbraInsetX &&
fabsf(factory.fOffset.fY) < umbraInsetY) {
factory.fOccluderType =
SpotVerticesFactory::OccluderType::kOpaqueCoversUmbra;
} else if (factory.fOffset.fX > w - umbraInsetX ||
factory.fOffset.fY > h - umbraInsetY) {
// There umbra is fully exposed, there is nothing to omit.
factory.fOccluderType = SpotVerticesFactory::OccluderType::kTransparent;
}
}
}
}
if (factory.fOccluderType == SpotVerticesFactory::OccluderType::kOpaque) {
factory.fOccluderType = SpotVerticesFactory::OccluderType::kTransparent;
}
draw_shadow(factory, canvas, shadowedPath, color, cache);
}
}
// Draw an offset spot shadow and outlining ambient shadow for the given path,
// without caching and using a function based on local position to compute the height.
void SkShadowUtils::DrawUncachedShadow(SkCanvas* canvas, const SkPath& path,
std::function<SkScalar(SkScalar, SkScalar)> heightFunc,
const SkPoint3& lightPos, SkScalar lightRadius,
SkScalar ambientAlpha, SkScalar spotAlpha, SkColor color,
uint32_t flags) {
SkAutoCanvasRestore acr(canvas, true);
SkMatrix viewMatrix = canvas->getTotalMatrix();
canvas->resetMatrix();
bool transparent = SkToBool(flags & SkShadowFlags::kTransparentOccluder_ShadowFlag);
if (ambientAlpha > 0) {
ambientAlpha = SkTMin(ambientAlpha, 1.f);
sk_sp<SkVertices> vertices = SkShadowTessellator::MakeAmbient(path, viewMatrix,
heightFunc, ambientAlpha,
transparent);
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()));
canvas->drawVertices(vertices, SkBlendMode::kModulate, paint);
}
if (spotAlpha > 0) {
spotAlpha = SkTMin(spotAlpha, 1.f);
sk_sp<SkVertices> vertices = SkShadowTessellator::MakeSpot(path, viewMatrix, heightFunc,
lightPos, lightRadius,
spotAlpha, transparent);
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()));
canvas->drawVertices(vertices, SkBlendMode::kModulate, paint);
}
}