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/*
* 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 SK_API 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*,
SkColorSpace*) 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*, SkColorSpace*) const {
return GrBlurredEdgeFragmentProcessor::Make(GrBlurredEdgeFragmentProcessor::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.
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;
}
static SkColor compute_render_color(SkColor color, float alpha, bool useTonalColor) {
if (useTonalColor) {
SkScalar colorScale;
SkScalar tonalAlpha;
SkColor4f color4f = SkColor4f::FromColor(color);
SkShadowUtils::ComputeTonalColorParams(color4f.fR,
color4f.fG,
color4f.fB,
alpha,
&colorScale, &tonalAlpha);
// After pre-multiplying, we want the alpha to be scaled by tonalAlpha, and
// the color scaled by colorScale. This scale factor gives that.
SkScalar unPremulScale = colorScale / tonalAlpha;
return SkColorSetARGB(tonalAlpha*255.999f, unPremulScale*SkColorGetR(color),
unPremulScale*SkColorGetG(color), unPremulScale*SkColorGetB(color));
}
return SkColorSetARGB(alpha*SkColorGetA(color), SkColorGetR(color),
SkColorGetG(color), SkColorGetB(color));
}
// 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,
SkScalar ambientAlpha, SkScalar spotAlpha, SkColor color,
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.fAmbientAlpha = SkScalarToFloat(ambientAlpha);
rec.fSpotAlpha = SkScalarToFloat(spotAlpha);
rec.fColor = color;
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();
bool useTonalColor = SkToBool(rec.fFlags & kTonalColor_ShadowFlag);
SkColor color = rec.fColor;
SkPoint3 zPlaneParams = rec.fZPlaneParams;
SkPoint3 devLightPos = map(viewMatrix, rec.fLightPos);
float lightRadius = rec.fLightRadius;
float ambientAlpha = rec.fAmbientAlpha;
if (ambientAlpha > 0) {
ambientAlpha = SkTMin(ambientAlpha, 1.f);
SkColor renderColor;
if (useTonalColor) {
renderColor = compute_render_color(SK_ColorBLACK, ambientAlpha, false);
} else {
renderColor = compute_render_color(color, ambientAlpha, false);
}
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(renderColor, 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, renderColor);
}
}
float spotAlpha = rec.fSpotAlpha;
if (spotAlpha > 0) {
spotAlpha = SkTMin(spotAlpha, 1.f);
SkColor renderColor = compute_render_color(color, spotAlpha, useTonalColor);
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(renderColor, 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(&center, 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, renderColor);
}
}
}