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* Copyright 2006 The Android Open Source Project
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#include "include/core/SkMallocPixelRef.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPicture.h"
#include "include/core/SkScalar.h"
#include "src/core/SkArenaAlloc.h"
#include "src/core/SkColorSpacePriv.h"
#include "src/core/SkColorSpaceXformSteps.h"
#include "src/core/SkMatrixProvider.h"
#include "src/core/SkRasterPipeline.h"
#include "src/core/SkReadBuffer.h"
#include "src/core/SkTLazy.h"
#include "src/core/SkVM.h"
#include "src/core/SkWriteBuffer.h"
#include "src/shaders/SkBitmapProcShader.h"
#include "src/shaders/SkColorShader.h"
#include "src/shaders/SkEmptyShader.h"
#include "src/shaders/SkPictureShader.h"
#include "src/shaders/SkShaderBase.h"
#include "src/gpu/GrFragmentProcessor.h"
SkShaderBase::SkShaderBase(const SkMatrix* localMatrix)
: fLocalMatrix(localMatrix ? *localMatrix : SkMatrix::I()) {
// Pre-cache so future calls to fLocalMatrix.getType() are threadsafe.
SkShaderBase::~SkShaderBase() {}
void SkShaderBase::flatten(SkWriteBuffer& buffer) const {
bool hasLocalM = !fLocalMatrix.isIdentity();
if (hasLocalM) {
SkShaderBase::totalLocalMatrix(const SkMatrix* preLocalMatrix) const {
SkTCopyOnFirstWrite<SkMatrix> m(fLocalMatrix);
if (preLocalMatrix) {
return m;
bool SkShaderBase::computeTotalInverse(const SkMatrix& ctm,
const SkMatrix* outerLocalMatrix,
SkMatrix* totalInverse) const {
return SkMatrix::Concat(ctm, *this->totalLocalMatrix(outerLocalMatrix)).invert(totalInverse);
bool SkShaderBase::asLuminanceColor(SkColor* colorPtr) const {
SkColor storage;
if (nullptr == colorPtr) {
colorPtr = &storage;
if (this->onAsLuminanceColor(colorPtr)) {
*colorPtr = SkColorSetA(*colorPtr, 0xFF); // we only return opaque
return true;
return false;
SkShaderBase::Context* SkShaderBase::makeContext(const ContextRec& rec, SkArenaAlloc* alloc) const {
// We always fall back to raster pipeline when perspective is present.
if (rec.fMatrix->hasPerspective() ||
fLocalMatrix.hasPerspective() ||
(rec.fLocalMatrix && rec.fLocalMatrix->hasPerspective()) ||
!this->computeTotalInverse(*rec.fMatrix, rec.fLocalMatrix, nullptr)) {
return nullptr;
return this->onMakeContext(rec, alloc);
return nullptr;
SkShaderBase::Context::Context(const SkShaderBase& shader, const ContextRec& rec)
: fShader(shader), fCTM(*rec.fMatrix)
// We should never use a context with perspective.
SkASSERT(!rec.fLocalMatrix || !rec.fLocalMatrix->hasPerspective());
// Because the context parameters must be valid at this point, we know that the matrix is
// invertible.
SkAssertResult(fShader.computeTotalInverse(*rec.fMatrix, rec.fLocalMatrix, &fTotalInverse));
fPaintAlpha = rec.fPaint->getAlpha();
SkShaderBase::Context::~Context() {}
bool SkShaderBase::ContextRec::isLegacyCompatible(SkColorSpace* shaderColorSpace) const {
// In legacy pipelines, shaders always produce premul (or opaque) and the destination is also
// always premul (or opaque). (And those "or opaque" caveats won't make any difference here.)
SkAlphaType shaderAT = kPremul_SkAlphaType,
dstAT = kPremul_SkAlphaType;
return 0 == SkColorSpaceXformSteps{shaderColorSpace, shaderAT,
fDstColorSpace, dstAT}.flags.mask();
SkImage* SkShader::isAImage(SkMatrix* localMatrix, SkTileMode xy[2]) const {
return as_SB(this)->onIsAImage(localMatrix, xy);
SkShader::GradientType SkShader::asAGradient(GradientInfo* info) const {
return kNone_GradientType;
std::unique_ptr<GrFragmentProcessor> SkShaderBase::asFragmentProcessor(const GrFPArgs&) const {
return nullptr;
sk_sp<SkShader> SkShaderBase::makeAsALocalMatrixShader(SkMatrix*) const {
return nullptr;
sk_sp<SkShader> SkShaders::Empty() { return sk_make_sp<SkEmptyShader>(); }
sk_sp<SkShader> SkShaders::Color(SkColor color) { return sk_make_sp<SkColorShader>(color); }
sk_sp<SkShader> SkBitmap::makeShader(SkTileMode tmx, SkTileMode tmy, const SkMatrix* lm) const {
if (lm && !lm->invert(nullptr)) {
return nullptr;
return SkMakeBitmapShader(*this, tmx, tmy, lm, kIfMutable_SkCopyPixelsMode);
sk_sp<SkShader> SkBitmap::makeShader(const SkMatrix* lm) const {
return this->makeShader(SkTileMode::kClamp, SkTileMode::kClamp, lm);
bool SkShaderBase::appendStages(const SkStageRec& rec) const {
return this->onAppendStages(rec);
bool SkShaderBase::onAppendStages(const SkStageRec& rec) const {
// SkShader::Context::shadeSpan() handles the paint opacity internally,
// but SkRasterPipelineBlitter applies it as a separate stage.
// We skip the internal shadeSpan() step by forcing the paint opaque.
SkTCopyOnFirstWrite<SkPaint> opaquePaint(rec.fPaint);
if (rec.fPaint.getAlpha() != SK_AlphaOPAQUE) {
ContextRec cr(*opaquePaint, rec.fMatrixProvider.localToDevice(), rec.fLocalM, rec.fDstColorType,
struct CallbackCtx : SkRasterPipeline_CallbackCtx {
sk_sp<const SkShader> shader;
Context* ctx;
auto cb = rec.fAlloc->make<CallbackCtx>();
cb->shader = sk_ref_sp(this);
cb->ctx = as_SB(this)->makeContext(cr, rec.fAlloc);
cb->fn = [](SkRasterPipeline_CallbackCtx* self, int active_pixels) {
auto c = (CallbackCtx*)self;
int x = (int)c->rgba[0],
y = (int)c->rgba[1];
SkPMColor tmp[SkRasterPipeline_kMaxStride];
c->ctx->shadeSpan(x,y, tmp, active_pixels);
for (int i = 0; i < active_pixels; i++) {
auto rgba_4f = SkPMColor4f::FromPMColor(tmp[i]);
memcpy(c->rgba + 4*i, rgba_4f.vec(), 4*sizeof(float));
if (cb->ctx) {
rec.fPipeline->append(SkRasterPipeline::callback, cb);
rec.fAlloc->make<SkColorSpaceXformSteps>(sk_srgb_singleton(), kPremul_SkAlphaType,
rec.fDstCS, kPremul_SkAlphaType)
return true;
return false;
skvm::Color SkShaderBase::program(skvm::Builder* p,
skvm::Coord device, skvm::Coord local, skvm::Color paint,
const SkMatrixProvider& matrices, const SkMatrix* localM,
SkFilterQuality quality, const SkColorInfo& dst,
skvm::Uniforms* uniforms, SkArenaAlloc* alloc) const {
// Shader subclasses should always act as if the destination were premul or opaque.
// SkVMBlitter handles all the coordination of unpremul itself, via premul.
SkColorInfo tweaked = dst.alphaType() == kUnpremul_SkAlphaType
? dst.makeAlphaType(kPremul_SkAlphaType)
: dst;
// Force opaque alpha for all opaque shaders.
// This is primarily nice in that we usually have a 1.0f constant splat
// somewhere in the program anyway, and this will let us drop the work the
// shader notionally does to produce alpha, p->extract(...), etc. in favor
// of that simple hoistable splat.
// More subtly, it makes isOpaque() a parameter to all shader program
// generation, guaranteeing that is-opaque bit is mixed into the overall
// shader program hash and blitter Key. This makes it safe for us to use
// that bit to make decisions when constructing an SkVMBlitter, like doing
// SrcOver -> Src strength reduction.
if (auto color = this->onProgram(p, device,local, paint, matrices,localM, quality,tweaked,
uniforms,alloc)) {
if (this->isOpaque()) {
color.a = p->splat(1.0f);
return color;
return {};
skvm::Color SkShaderBase::onProgram(skvm::Builder*,
skvm::Coord device, skvm::Coord local, skvm::Color paint,
const SkMatrixProvider&, const SkMatrix* localM,
SkFilterQuality quality, const SkColorInfo& dst,
skvm::Uniforms* uniforms, SkArenaAlloc* alloc) const {
// SkDebugf("cannot onProgram %s\n", this->getTypeName());
return {};
// need a cheap way to invert the alpha channel of a shader (i.e. 1 - a)
sk_sp<SkShader> SkShaderBase::makeInvertAlpha() const {
return this->makeWithColorFilter(SkColorFilters::Blend(0xFFFFFFFF, SkBlendMode::kSrcOut));
skvm::Coord SkShaderBase::ApplyMatrix(skvm::Builder* p, const SkMatrix& m,
skvm::Coord coord, skvm::Uniforms* uniforms) {
skvm::F32 x = coord.x,
y = coord.y;
if (m.isIdentity()) {
// That was easy.
} else if (m.isTranslate()) {
x = p->add(x, p->uniformF(uniforms->pushF(m[2])));
y = p->add(y, p->uniformF(uniforms->pushF(m[5])));
} else if (m.isScaleTranslate()) {
x = p->mad(x, p->uniformF(uniforms->pushF(m[0])), p->uniformF(uniforms->pushF(m[2])));
y = p->mad(y, p->uniformF(uniforms->pushF(m[4])), p->uniformF(uniforms->pushF(m[5])));
} else { // Affine or perspective.
auto dot = [&,x,y](int row) {
return p->mad(x, p->uniformF(uniforms->pushF(m[3*row+0])),
p->mad(y, p->uniformF(uniforms->pushF(m[3*row+1])),
x = dot(0);
y = dot(1);
if (m.hasPerspective()) {
x = x * (1.0f / dot(2));
y = y * (1.0f / dot(2));
return {x,y};
skvm::Color SkEmptyShader::onProgram(skvm::Builder*, skvm::Coord, skvm::Coord, skvm::Color,
const SkMatrixProvider&, const SkMatrix*,
SkFilterQuality, const SkColorInfo&,
skvm::Uniforms*, SkArenaAlloc*) const {
return {}; // signal failure
sk_sp<SkFlattenable> SkEmptyShader::CreateProc(SkReadBuffer&) {
return SkShaders::Empty();