libs/hwui/effects/GainmapRenderer.cpp - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2023 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "GainmapRenderer.h"

 #include <SkGainmapShader.h>

 #include "Gainmap.h"
 #include "Rect.h"
 #include "utils/Trace.h"

 #ifdef __ANDROID__
 #include "include/core/SkColorSpace.h"
 #include "include/core/SkImage.h"
 #include "include/core/SkShader.h"
 #include "include/effects/SkRuntimeEffect.h"
 #include "include/private/SkGainmapInfo.h"
 #include "renderthread/CanvasContext.h"
 #include "src/core/SkColorFilterPriv.h"
 #include "src/core/SkImageInfoPriv.h"
 #include "src/core/SkRuntimeEffectPriv.h"
 #endif

 namespace android::uirenderer {

 using namespace renderthread;

 float getTargetHdrSdrRatio(const SkColorSpace* destColorspace) {
     // We should always have a known destination colorspace. If we don't we must be in some
     // legacy mode where we're lost and also definitely not going to HDR
     if (destColorspace == nullptr) {
         return 1.f;
     }

     constexpr float GenericSdrWhiteNits = 203.f;
     constexpr float maxPQLux = 10000.f;
     constexpr float maxHLGLux = 1000.f;
     skcms_TransferFunction destTF;
     destColorspace->transferFn(&destTF);
     if (skcms_TransferFunction_isPQish(&destTF)) {
         return maxPQLux / GenericSdrWhiteNits;
     } else if (skcms_TransferFunction_isHLGish(&destTF)) {
         return maxHLGLux / GenericSdrWhiteNits;
 #ifdef __ANDROID__
     } else if (RenderThread::isCurrent()) {
         CanvasContext* context = CanvasContext::getActiveContext();
         return context ? context->targetSdrHdrRatio() : 1.f;
 #endif
     }
     return 1.f;
 }

 void DrawGainmapBitmap(SkCanvas* c, const sk_sp<const SkImage>& image, const SkRect& src,
                        const SkRect& dst, const SkSamplingOptions& sampling, const SkPaint* paint,
                        SkCanvas::SrcRectConstraint constraint,
                        const sk_sp<const SkImage>& gainmapImage, const SkGainmapInfo& gainmapInfo) {
     ATRACE_CALL();
 #ifdef __ANDROID__
     auto destColorspace = c->imageInfo().refColorSpace();
     float targetSdrHdrRatio = getTargetHdrSdrRatio(destColorspace.get());
     if (targetSdrHdrRatio > 1.f && gainmapImage) {
         SkPaint gainmapPaint = *paint;
         float sX = gainmapImage->width() / (float)image->width();
         float sY = gainmapImage->height() / (float)image->height();
         SkRect gainmapSrc = src;
         // TODO: Tweak rounding?
         gainmapSrc.fLeft *= sX;
         gainmapSrc.fRight *= sX;
         gainmapSrc.fTop *= sY;
         gainmapSrc.fBottom *= sY;
         auto shader =
                 SkGainmapShader::Make(image, src, sampling, gainmapImage, gainmapSrc, sampling,
                                       gainmapInfo, dst, targetSdrHdrRatio, destColorspace);
         gainmapPaint.setShader(shader);
         c->drawRect(dst, gainmapPaint);
     } else
 #endif
         c->drawImageRect(image.get(), src, dst, sampling, paint, constraint);
 }

 #ifdef __ANDROID__

 static constexpr char gGainmapSKSL[] = R"SKSL(
     uniform shader base;
     uniform shader gainmap;
     uniform colorFilter workingSpaceToLinearSrgb;
     uniform half4 logRatioMin;
     uniform half4 logRatioMax;
     uniform half4 gainmapGamma;
     uniform half4 epsilonSdr;
     uniform half4 epsilonHdr;
     uniform half W;
     uniform int gainmapIsAlpha;
     uniform int gainmapIsRed;
     uniform int singleChannel;
     uniform int noGamma;

     half4 toDest(half4 working) {
         half4 ls = workingSpaceToLinearSrgb.eval(working);
         vec3 dest = fromLinearSrgb(ls.rgb);
         return half4(dest.r, dest.g, dest.b, ls.a);
     }

     half4 main(float2 coord) {
         half4 S = base.eval(coord);
         half4 G = gainmap.eval(coord);
         if (gainmapIsAlpha == 1) {
             G = half4(G.a, G.a, G.a, 1.0);
         }
         if (gainmapIsRed == 1) {
             G = half4(G.r, G.r, G.r, 1.0);
         }
         if (singleChannel == 1) {
             half L;
             if (noGamma == 1) {
                 L = mix(logRatioMin.r, logRatioMax.r, G.r);
             } else {
                 L = mix(logRatioMin.r, logRatioMax.r, pow(G.r, gainmapGamma.r));
             }
             half3 H = (S.rgb + epsilonSdr.rgb) * exp(L * W) - epsilonHdr.rgb;
             return toDest(half4(H.r, H.g, H.b, S.a));
         } else {
             half3 L;
             if (noGamma == 1) {
                 L = mix(logRatioMin.rgb, logRatioMax.rgb, G.rgb);
             } else {
                 L = mix(logRatioMin.rgb, logRatioMax.rgb, pow(G.rgb, gainmapGamma.rgb));
             }
             half3 H = (S.rgb + epsilonSdr.rgb) * exp(L * W) - epsilonHdr.rgb;
             return toDest(half4(H.r, H.g, H.b, S.a));
         }
     }
 )SKSL";

 static sk_sp<SkRuntimeEffect> gainmap_apply_effect() {
     static const SkRuntimeEffect* effect = []() -> SkRuntimeEffect* {
         auto buildResult = SkRuntimeEffect::MakeForShader(SkString(gGainmapSKSL), {});
         if (buildResult.effect) {
             return buildResult.effect.release();
         } else {
             LOG_ALWAYS_FATAL("Failed to build gainmap shader: %s", buildResult.errorText.c_str());
         }
     }();
     SkASSERT(effect);
     return sk_ref_sp(effect);
 }

 static bool all_channels_equal(const SkColor4f& c) {
     return c.fR == c.fG && c.fR == c.fB;
 }

 class DeferredGainmapShader {
 private:
     sk_sp<SkRuntimeEffect> mShader{gainmap_apply_effect()};
     SkRuntimeShaderBuilder mBuilder{mShader};
     SkGainmapInfo mGainmapInfo;
     std::mutex mUniformGuard;

     void setupChildren(const sk_sp<const SkImage>& baseImage,
                        const sk_sp<const SkImage>& gainmapImage, SkTileMode tileModeX,
                        SkTileMode tileModeY, const SkSamplingOptions& samplingOptions) {
         sk_sp<SkColorSpace> baseColorSpace =
                 baseImage->colorSpace() ? baseImage->refColorSpace() : SkColorSpace::MakeSRGB();

         // Determine the color space in which the gainmap math is to be applied.
         sk_sp<SkColorSpace> gainmapMathColorSpace = baseColorSpace->makeLinearGamma();

         // Create a color filter to transform from the base image's color space to the color space
         // in which the gainmap is to be applied.
         auto colorXformSdrToGainmap =
                 SkColorFilterPriv::MakeColorSpaceXform(baseColorSpace, gainmapMathColorSpace);

         // The base image shader will convert into the color space in which the gainmap is applied.
         auto baseImageShader = baseImage->makeRawShader(tileModeX, tileModeY, samplingOptions)
                                        ->makeWithColorFilter(colorXformSdrToGainmap);

         // The gainmap image shader will ignore any color space that the gainmap has.
         const SkMatrix gainmapRectToDstRect =
                 SkMatrix::RectToRect(SkRect::MakeWH(gainmapImage->width(), gainmapImage->height()),
                                      SkRect::MakeWH(baseImage->width(), baseImage->height()));
         auto gainmapImageShader = gainmapImage->makeRawShader(tileModeX, tileModeY, samplingOptions,
                                                               &gainmapRectToDstRect);

         // Create a color filter to transform from the color space in which the gainmap is applied
         // to the intermediate destination color space.
         auto colorXformGainmapToDst = SkColorFilterPriv::MakeColorSpaceXform(
                 gainmapMathColorSpace, SkColorSpace::MakeSRGBLinear());

         mBuilder.child("base") = std::move(baseImageShader);
         mBuilder.child("gainmap") = std::move(gainmapImageShader);
         mBuilder.child("workingSpaceToLinearSrgb") = std::move(colorXformGainmapToDst);
     }

     void setupGenericUniforms(const sk_sp<const SkImage>& gainmapImage,
                               const SkGainmapInfo& gainmapInfo) {
         const SkColor4f logRatioMin({sk_float_log(gainmapInfo.fGainmapRatioMin.fR),
                                      sk_float_log(gainmapInfo.fGainmapRatioMin.fG),
                                      sk_float_log(gainmapInfo.fGainmapRatioMin.fB), 1.f});
         const SkColor4f logRatioMax({sk_float_log(gainmapInfo.fGainmapRatioMax.fR),
                                      sk_float_log(gainmapInfo.fGainmapRatioMax.fG),
                                      sk_float_log(gainmapInfo.fGainmapRatioMax.fB), 1.f});
         const int noGamma = gainmapInfo.fGainmapGamma.fR == 1.f &&
                             gainmapInfo.fGainmapGamma.fG == 1.f &&
                             gainmapInfo.fGainmapGamma.fB == 1.f;
         const uint32_t colorTypeFlags = SkColorTypeChannelFlags(gainmapImage->colorType());
         const int gainmapIsAlpha = colorTypeFlags == kAlpha_SkColorChannelFlag;
         const int gainmapIsRed = colorTypeFlags == kRed_SkColorChannelFlag;
         const int singleChannel = all_channels_equal(gainmapInfo.fGainmapGamma) &&
                                   all_channels_equal(gainmapInfo.fGainmapRatioMin) &&
                                   all_channels_equal(gainmapInfo.fGainmapRatioMax) &&
                                   (colorTypeFlags == kGray_SkColorChannelFlag ||
                                    colorTypeFlags == kAlpha_SkColorChannelFlag ||
                                    colorTypeFlags == kRed_SkColorChannelFlag);
         mBuilder.uniform("logRatioMin") = logRatioMin;
         mBuilder.uniform("logRatioMax") = logRatioMax;
         mBuilder.uniform("gainmapGamma") = gainmapInfo.fGainmapGamma;
         mBuilder.uniform("epsilonSdr") = gainmapInfo.fEpsilonSdr;
         mBuilder.uniform("epsilonHdr") = gainmapInfo.fEpsilonHdr;
         mBuilder.uniform("noGamma") = noGamma;
         mBuilder.uniform("singleChannel") = singleChannel;
         mBuilder.uniform("gainmapIsAlpha") = gainmapIsAlpha;
         mBuilder.uniform("gainmapIsRed") = gainmapIsRed;
     }

     sk_sp<const SkData> build(float targetHdrSdrRatio) {
         sk_sp<const SkData> uniforms;
         {
             // If we are called concurrently from multiple threads, we need to guard the call
             // to writableUniforms() which mutates mUniform. This is otherwise safe because
             // writeableUniforms() will make a copy if it's not unique before mutating
             // This can happen if a BitmapShader is used on multiple canvas', such as a
             // software + hardware canvas, which is otherwise valid as SkShader is "immutable"
             std::lock_guard _lock(mUniformGuard);
             // Compute the weight parameter that will be used to blend between the images.
             float W = 0.f;
             if (targetHdrSdrRatio > mGainmapInfo.fDisplayRatioSdr) {
                 if (targetHdrSdrRatio < mGainmapInfo.fDisplayRatioHdr) {
                     W = (sk_float_log(targetHdrSdrRatio) -
                          sk_float_log(mGainmapInfo.fDisplayRatioSdr)) /
                         (sk_float_log(mGainmapInfo.fDisplayRatioHdr) -
                          sk_float_log(mGainmapInfo.fDisplayRatioSdr));
                 } else {
                     W = 1.f;
                 }
             }
             mBuilder.uniform("W") = W;
             uniforms = mBuilder.uniforms();
         }
         return uniforms;
     }

 public:
     explicit DeferredGainmapShader(const sk_sp<const SkImage>& image,
                                    const sk_sp<const SkImage>& gainmapImage,
                                    const SkGainmapInfo& gainmapInfo, SkTileMode tileModeX,
                                    SkTileMode tileModeY, const SkSamplingOptions& sampling) {
         mGainmapInfo = gainmapInfo;
         setupChildren(image, gainmapImage, tileModeX, tileModeY, sampling);
         setupGenericUniforms(gainmapImage, gainmapInfo);
     }

     static sk_sp<SkShader> Make(const sk_sp<const SkImage>& image,
                                 const sk_sp<const SkImage>& gainmapImage,
                                 const SkGainmapInfo& gainmapInfo, SkTileMode tileModeX,
                                 SkTileMode tileModeY, const SkSamplingOptions& sampling) {
         auto deferredHandler = std::make_shared<DeferredGainmapShader>(
                 image, gainmapImage, gainmapInfo, tileModeX, tileModeY, sampling);
         auto callback =
                 [deferredHandler](const SkRuntimeEffectPriv::UniformsCallbackContext& renderContext)
                 -> sk_sp<const SkData> {
             return deferredHandler->build(getTargetHdrSdrRatio(renderContext.fDstColorSpace));
         };
         return SkRuntimeEffectPriv::MakeDeferredShader(deferredHandler->mShader.get(), callback,
                                                        deferredHandler->mBuilder.children());
     }
 };

 sk_sp<SkShader> MakeGainmapShader(const sk_sp<const SkImage>& image,
                                   const sk_sp<const SkImage>& gainmapImage,
                                   const SkGainmapInfo& gainmapInfo, SkTileMode tileModeX,
                                   SkTileMode tileModeY, const SkSamplingOptions& sampling) {
     return DeferredGainmapShader::Make(image, gainmapImage, gainmapInfo, tileModeX, tileModeY,
                                        sampling);
 }

 #else  // __ANDROID__

 sk_sp<SkShader> MakeGainmapShader(const sk_sp<const SkImage>& image,
                                   const sk_sp<const SkImage>& gainmapImage,
                                   const SkGainmapInfo& gainmapInfo, SkTileMode tileModeX,
                                   SkTileMode tileModeY, const SkSamplingOptions& sampling) {
         return nullptr;
 }

 #endif  // __ANDROID__

 }  // namespace android::uirenderer
	/*
	* Copyright (C) 2023 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "GainmapRenderer.h"

	#include <SkGainmapShader.h>

	#include "Gainmap.h"
	#include "Rect.h"
	#include "utils/Trace.h"

	#ifdef __ANDROID__
	#include "include/core/SkColorSpace.h"
	#include "include/core/SkImage.h"
	#include "include/core/SkShader.h"
	#include "include/effects/SkRuntimeEffect.h"
	#include "include/private/SkGainmapInfo.h"
	#include "renderthread/CanvasContext.h"
	#include "src/core/SkColorFilterPriv.h"
	#include "src/core/SkImageInfoPriv.h"
	#include "src/core/SkRuntimeEffectPriv.h"
	#endif

	namespace android::uirenderer {

	using namespace renderthread;

	float getTargetHdrSdrRatio(const SkColorSpace* destColorspace) {
	// We should always have a known destination colorspace. If we don't we must be in some
	// legacy mode where we're lost and also definitely not going to HDR
	if (destColorspace == nullptr) {
	return 1.f;
	}

	constexpr float GenericSdrWhiteNits = 203.f;
	constexpr float maxPQLux = 10000.f;
	constexpr float maxHLGLux = 1000.f;
	skcms_TransferFunction destTF;
	destColorspace->transferFn(&destTF);
	if (skcms_TransferFunction_isPQish(&destTF)) {
	return maxPQLux / GenericSdrWhiteNits;
	} else if (skcms_TransferFunction_isHLGish(&destTF)) {
	return maxHLGLux / GenericSdrWhiteNits;
	#ifdef __ANDROID__
	} else if (RenderThread::isCurrent()) {
	CanvasContext* context = CanvasContext::getActiveContext();
	return context ? context->targetSdrHdrRatio() : 1.f;
	#endif
	}
	return 1.f;
	}

	void DrawGainmapBitmap(SkCanvas* c, const sk_sp<const SkImage>& image, const SkRect& src,
	const SkRect& dst, const SkSamplingOptions& sampling, const SkPaint* paint,
	SkCanvas::SrcRectConstraint constraint,
	const sk_sp<const SkImage>& gainmapImage, const SkGainmapInfo& gainmapInfo) {
	ATRACE_CALL();
	#ifdef __ANDROID__
	auto destColorspace = c->imageInfo().refColorSpace();
	float targetSdrHdrRatio = getTargetHdrSdrRatio(destColorspace.get());
	if (targetSdrHdrRatio > 1.f && gainmapImage) {
	SkPaint gainmapPaint = *paint;
	float sX = gainmapImage->width() / (float)image->width();
	float sY = gainmapImage->height() / (float)image->height();
	SkRect gainmapSrc = src;
	// TODO: Tweak rounding?
	gainmapSrc.fLeft *= sX;
	gainmapSrc.fRight *= sX;
	gainmapSrc.fTop *= sY;
	gainmapSrc.fBottom *= sY;
	auto shader =
	SkGainmapShader::Make(image, src, sampling, gainmapImage, gainmapSrc, sampling,
	gainmapInfo, dst, targetSdrHdrRatio, destColorspace);
	gainmapPaint.setShader(shader);
	c->drawRect(dst, gainmapPaint);
	} else
	#endif
	c->drawImageRect(image.get(), src, dst, sampling, paint, constraint);
	}

	#ifdef __ANDROID__

	static constexpr char gGainmapSKSL[] = R"SKSL(
	uniform shader base;
	uniform shader gainmap;
	uniform colorFilter workingSpaceToLinearSrgb;
	uniform half4 logRatioMin;
	uniform half4 logRatioMax;
	uniform half4 gainmapGamma;
	uniform half4 epsilonSdr;
	uniform half4 epsilonHdr;
	uniform half W;
	uniform int gainmapIsAlpha;
	uniform int gainmapIsRed;
	uniform int singleChannel;
	uniform int noGamma;

	half4 toDest(half4 working) {
	half4 ls = workingSpaceToLinearSrgb.eval(working);
	vec3 dest = fromLinearSrgb(ls.rgb);
	return half4(dest.r, dest.g, dest.b, ls.a);
	}

	half4 main(float2 coord) {
	half4 S = base.eval(coord);
	half4 G = gainmap.eval(coord);
	if (gainmapIsAlpha == 1) {
	G = half4(G.a, G.a, G.a, 1.0);
	}
	if (gainmapIsRed == 1) {
	G = half4(G.r, G.r, G.r, 1.0);
	}
	if (singleChannel == 1) {
	half L;
	if (noGamma == 1) {
	L = mix(logRatioMin.r, logRatioMax.r, G.r);
	} else {
	L = mix(logRatioMin.r, logRatioMax.r, pow(G.r, gainmapGamma.r));
	}
	half3 H = (S.rgb + epsilonSdr.rgb) * exp(L * W) - epsilonHdr.rgb;
	return toDest(half4(H.r, H.g, H.b, S.a));
	} else {
	half3 L;
	if (noGamma == 1) {
	L = mix(logRatioMin.rgb, logRatioMax.rgb, G.rgb);
	} else {
	L = mix(logRatioMin.rgb, logRatioMax.rgb, pow(G.rgb, gainmapGamma.rgb));
	}
	half3 H = (S.rgb + epsilonSdr.rgb) * exp(L * W) - epsilonHdr.rgb;
	return toDest(half4(H.r, H.g, H.b, S.a));
	}
	}
	)SKSL";

	static sk_sp<SkRuntimeEffect> gainmap_apply_effect() {
	static const SkRuntimeEffect* effect = []() -> SkRuntimeEffect* {
	auto buildResult = SkRuntimeEffect::MakeForShader(SkString(gGainmapSKSL), {});
	if (buildResult.effect) {
	return buildResult.effect.release();
	} else {
	LOG_ALWAYS_FATAL("Failed to build gainmap shader: %s", buildResult.errorText.c_str());
	}
	}();
	SkASSERT(effect);
	return sk_ref_sp(effect);
	}

	static bool all_channels_equal(const SkColor4f& c) {
	return c.fR == c.fG && c.fR == c.fB;
	}

	class DeferredGainmapShader {
	private:
	sk_sp<SkRuntimeEffect> mShader{gainmap_apply_effect()};
	SkRuntimeShaderBuilder mBuilder{mShader};
	SkGainmapInfo mGainmapInfo;
	std::mutex mUniformGuard;

	void setupChildren(const sk_sp<const SkImage>& baseImage,
	const sk_sp<const SkImage>& gainmapImage, SkTileMode tileModeX,
	SkTileMode tileModeY, const SkSamplingOptions& samplingOptions) {
	sk_sp<SkColorSpace> baseColorSpace =
	baseImage->colorSpace() ? baseImage->refColorSpace() : SkColorSpace::MakeSRGB();

	// Determine the color space in which the gainmap math is to be applied.
	sk_sp<SkColorSpace> gainmapMathColorSpace = baseColorSpace->makeLinearGamma();

	// Create a color filter to transform from the base image's color space to the color space
	// in which the gainmap is to be applied.
	auto colorXformSdrToGainmap =
	SkColorFilterPriv::MakeColorSpaceXform(baseColorSpace, gainmapMathColorSpace);

	// The base image shader will convert into the color space in which the gainmap is applied.
	auto baseImageShader = baseImage->makeRawShader(tileModeX, tileModeY, samplingOptions)
	->makeWithColorFilter(colorXformSdrToGainmap);

	// The gainmap image shader will ignore any color space that the gainmap has.
	const SkMatrix gainmapRectToDstRect =
	SkMatrix::RectToRect(SkRect::MakeWH(gainmapImage->width(), gainmapImage->height()),
	SkRect::MakeWH(baseImage->width(), baseImage->height()));
	auto gainmapImageShader = gainmapImage->makeRawShader(tileModeX, tileModeY, samplingOptions,
	&gainmapRectToDstRect);

	// Create a color filter to transform from the color space in which the gainmap is applied
	// to the intermediate destination color space.
	auto colorXformGainmapToDst = SkColorFilterPriv::MakeColorSpaceXform(
	gainmapMathColorSpace, SkColorSpace::MakeSRGBLinear());

	mBuilder.child("base") = std::move(baseImageShader);
	mBuilder.child("gainmap") = std::move(gainmapImageShader);
	mBuilder.child("workingSpaceToLinearSrgb") = std::move(colorXformGainmapToDst);
	}

	void setupGenericUniforms(const sk_sp<const SkImage>& gainmapImage,
	const SkGainmapInfo& gainmapInfo) {
	const SkColor4f logRatioMin({sk_float_log(gainmapInfo.fGainmapRatioMin.fR),
	sk_float_log(gainmapInfo.fGainmapRatioMin.fG),
	sk_float_log(gainmapInfo.fGainmapRatioMin.fB), 1.f});
	const SkColor4f logRatioMax({sk_float_log(gainmapInfo.fGainmapRatioMax.fR),
	sk_float_log(gainmapInfo.fGainmapRatioMax.fG),
	sk_float_log(gainmapInfo.fGainmapRatioMax.fB), 1.f});
	const int noGamma = gainmapInfo.fGainmapGamma.fR == 1.f &&
	gainmapInfo.fGainmapGamma.fG == 1.f &&
	gainmapInfo.fGainmapGamma.fB == 1.f;
	const uint32_t colorTypeFlags = SkColorTypeChannelFlags(gainmapImage->colorType());
	const int gainmapIsAlpha = colorTypeFlags == kAlpha_SkColorChannelFlag;
	const int gainmapIsRed = colorTypeFlags == kRed_SkColorChannelFlag;
	const int singleChannel = all_channels_equal(gainmapInfo.fGainmapGamma) &&
	all_channels_equal(gainmapInfo.fGainmapRatioMin) &&
	all_channels_equal(gainmapInfo.fGainmapRatioMax) &&
	(colorTypeFlags == kGray_SkColorChannelFlag \|\|
	colorTypeFlags == kAlpha_SkColorChannelFlag \|\|
	colorTypeFlags == kRed_SkColorChannelFlag);
	mBuilder.uniform("logRatioMin") = logRatioMin;
	mBuilder.uniform("logRatioMax") = logRatioMax;
	mBuilder.uniform("gainmapGamma") = gainmapInfo.fGainmapGamma;
	mBuilder.uniform("epsilonSdr") = gainmapInfo.fEpsilonSdr;
	mBuilder.uniform("epsilonHdr") = gainmapInfo.fEpsilonHdr;
	mBuilder.uniform("noGamma") = noGamma;
	mBuilder.uniform("singleChannel") = singleChannel;
	mBuilder.uniform("gainmapIsAlpha") = gainmapIsAlpha;
	mBuilder.uniform("gainmapIsRed") = gainmapIsRed;
	}

	sk_sp<const SkData> build(float targetHdrSdrRatio) {
	sk_sp<const SkData> uniforms;
	{
	// If we are called concurrently from multiple threads, we need to guard the call
	// to writableUniforms() which mutates mUniform. This is otherwise safe because
	// writeableUniforms() will make a copy if it's not unique before mutating
	// This can happen if a BitmapShader is used on multiple canvas', such as a
	// software + hardware canvas, which is otherwise valid as SkShader is "immutable"
	std::lock_guard _lock(mUniformGuard);
	// Compute the weight parameter that will be used to blend between the images.
	float W = 0.f;
	if (targetHdrSdrRatio > mGainmapInfo.fDisplayRatioSdr) {
	if (targetHdrSdrRatio < mGainmapInfo.fDisplayRatioHdr) {
	W = (sk_float_log(targetHdrSdrRatio) -
	sk_float_log(mGainmapInfo.fDisplayRatioSdr)) /
	(sk_float_log(mGainmapInfo.fDisplayRatioHdr) -
	sk_float_log(mGainmapInfo.fDisplayRatioSdr));
	} else {
	W = 1.f;
	}
	}
	mBuilder.uniform("W") = W;
	uniforms = mBuilder.uniforms();
	}
	return uniforms;
	}

	public:
	explicit DeferredGainmapShader(const sk_sp<const SkImage>& image,
	const sk_sp<const SkImage>& gainmapImage,
	const SkGainmapInfo& gainmapInfo, SkTileMode tileModeX,
	SkTileMode tileModeY, const SkSamplingOptions& sampling) {
	mGainmapInfo = gainmapInfo;
	setupChildren(image, gainmapImage, tileModeX, tileModeY, sampling);
	setupGenericUniforms(gainmapImage, gainmapInfo);
	}

	static sk_sp<SkShader> Make(const sk_sp<const SkImage>& image,
	const sk_sp<const SkImage>& gainmapImage,
	const SkGainmapInfo& gainmapInfo, SkTileMode tileModeX,
	SkTileMode tileModeY, const SkSamplingOptions& sampling) {
	auto deferredHandler = std::make_shared<DeferredGainmapShader>(
	image, gainmapImage, gainmapInfo, tileModeX, tileModeY, sampling);
	auto callback =
	[deferredHandler](const SkRuntimeEffectPriv::UniformsCallbackContext& renderContext)
	-> sk_sp<const SkData> {
	return deferredHandler->build(getTargetHdrSdrRatio(renderContext.fDstColorSpace));
	};
	return SkRuntimeEffectPriv::MakeDeferredShader(deferredHandler->mShader.get(), callback,
	deferredHandler->mBuilder.children());
	}
	};

	sk_sp<SkShader> MakeGainmapShader(const sk_sp<const SkImage>& image,
	const sk_sp<const SkImage>& gainmapImage,
	const SkGainmapInfo& gainmapInfo, SkTileMode tileModeX,
	SkTileMode tileModeY, const SkSamplingOptions& sampling) {
	return DeferredGainmapShader::Make(image, gainmapImage, gainmapInfo, tileModeX, tileModeY,
	sampling);
	}

	#else // __ANDROID__

	sk_sp<SkShader> MakeGainmapShader(const sk_sp<const SkImage>& image,
	const sk_sp<const SkImage>& gainmapImage,
	const SkGainmapInfo& gainmapInfo, SkTileMode tileModeX,
	SkTileMode tileModeY, const SkSamplingOptions& sampling) {
	return nullptr;
	}

	#endif // __ANDROID__

	} // namespace android::uirenderer