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* Copyright 2020 Google LLC
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkRuntimeEffectPriv_DEFINED
#define SkRuntimeEffectPriv_DEFINED
#include "include/effects/SkRuntimeEffect.h"
#include "include/private/SkColorData.h"
#include "src/core/SkVM.h"
#include <functional>
namespace SkSL {
class Context;
class Variable;
struct Program;
class SkCapabilities;
struct SkColorSpaceXformSteps;
class SkRuntimeEffectPriv {
struct UniformsCallbackContext {
const SkColorSpace* fDstColorSpace;
// Private (experimental) API for creating runtime shaders with late-bound uniforms.
// The callback must produce a uniform data blob of the correct size for the effect.
// It is invoked at "draw" time (essentially, when a draw call is made against the canvas
// using the resulting shader). There are no strong guarantees about timing.
// Serializing the resulting shader will immediately invoke the callback (and record the
// resulting uniforms).
using UniformsCallback = std::function<sk_sp<const SkData>(const UniformsCallbackContext&)>;
static sk_sp<SkShader> MakeDeferredShader(const SkRuntimeEffect* effect,
UniformsCallback uniformsCallback,
SkSpan<SkRuntimeEffect::ChildPtr> children,
const SkMatrix* localMatrix = nullptr);
// Helper function when creating an effect for a GrSkSLFP that verifies an effect will
// implement the GrFragmentProcessor "constant output for constant input" optimization flag.
static bool SupportsConstantOutputForConstantInput(const SkRuntimeEffect* effect) {
// This optimization is only implemented for color filters without any children.
if (!effect->allowColorFilter() || !effect->children().empty()) {
return false;
#if defined(SK_ENABLE_SKVM)
return effect->getFilterColorProgram();
return true;
static uint32_t Hash(const SkRuntimeEffect& effect) {
return effect.hash();
static const SkSL::Program& Program(const SkRuntimeEffect& effect) {
return *effect.fBaseProgram;
static SkRuntimeEffect::Options ES3Options() {
SkRuntimeEffect::Options options;
options.maxVersionAllowed = SkSL::Version::k300;
return options;
static void AllowPrivateAccess(SkRuntimeEffect::Options* options) {
options->allowPrivateAccess = true;
static SkRuntimeEffect::Uniform VarAsUniform(const SkSL::Variable&,
const SkSL::Context&,
size_t* offset);
// If there are layout(color) uniforms then this performs color space transformation on the
// color values and returns a new SkData. Otherwise, the original data is returned.
static sk_sp<const SkData> TransformUniforms(SkSpan<const SkRuntimeEffect::Uniform> uniforms,
sk_sp<const SkData> originalData,
const SkColorSpaceXformSteps&);
static sk_sp<const SkData> TransformUniforms(SkSpan<const SkRuntimeEffect::Uniform> uniforms,
sk_sp<const SkData> originalData,
const SkColorSpace* dstCS);
static bool CanDraw(const SkCapabilities*, const SkSL::Program*);
static bool CanDraw(const SkCapabilities*, const SkRuntimeEffect*);
// These internal APIs for creating runtime effects vary from the public API in two ways:
// 1) they're used in contexts where it's not useful to receive an error message;
// 2) they're cached.
// Users of the public SkRuntimeEffect::Make*() can of course cache however they like themselves;
// keeping these APIs private means users will not be forced into our cache or cache policy.
sk_sp<SkRuntimeEffect> SkMakeCachedRuntimeEffect(
SkRuntimeEffect::Result (*make)(SkString sksl, const SkRuntimeEffect::Options&),
SkString sksl);
inline sk_sp<SkRuntimeEffect> SkMakeCachedRuntimeEffect(
SkRuntimeEffect::Result (*make)(SkString, const SkRuntimeEffect::Options&),
const char* sksl) {
return SkMakeCachedRuntimeEffect(make, SkString{sksl});
// Internal API that assumes (and asserts) that the shader code is valid, but does no internal
// caching. Used when the caller will cache the result in a static variable. Ownership is passed to
// the caller; the effect will be leaked if it the pointer is not stored or explicitly deleted.
inline SkRuntimeEffect* SkMakeRuntimeEffect(
SkRuntimeEffect::Result (*make)(SkString, const SkRuntimeEffect::Options&),
const char* sksl,
SkRuntimeEffect::Options options = SkRuntimeEffect::Options{}) {
#if defined(SK_DEBUG)
// Our SKSL snippets we embed in Skia should not have comments or excess indentation.
// Removing them helps trim down code size and speeds up parsing
if (SkStrContains(sksl, "//") || SkStrContains(sksl, " ")) {
SkDEBUGFAILF("Found SkSL snippet that can be minified: \n %s\n", sksl);
auto result = make(SkString{sksl}, options);
if (!result.effect) {
SK_ABORT("%s", result.errorText.c_str());
return result.effect.release();
#endif // SK_ENABLE_SKSL
#endif // SkRuntimeEffectPriv_DEFINED