| /* |
| * Copyright 2023 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "include/private/SkGainmapShader.h" |
| |
| #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 "src/core/SkColorFilterPriv.h" |
| |
| #ifdef SK_ENABLE_SKSL |
| static constexpr char gGainmapSKSL[] = |
| "uniform shader base;" |
| "uniform shader gainmap;" |
| "uniform half4 logRatioMin;" |
| "uniform half4 logRatioMax;" |
| "uniform half4 gainmapGamma;" |
| "uniform half epsilonSdr;" |
| "uniform half epsilonHdr;" |
| "uniform half W;" |
| "uniform int singleChannel;" |
| "uniform int noGamma;" |
| "" |
| "half4 main(float2 coord) {" |
| " half4 S = base.eval(coord);" |
| " half4 G = gainmap.eval(coord);" |
| " 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) * exp(L * W) - epsilonHdr;" |
| " return 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) * exp(L * W) - epsilonHdr;" |
| " return half4(H.r, H.g, H.b, S.a);" |
| " }" |
| "}"; |
| |
| static sk_sp<SkRuntimeEffect> gainmap_apply_effect() { |
| static const SkRuntimeEffect* effect = |
| SkRuntimeEffect::MakeForShader(SkString(gGainmapSKSL), {}).effect.release(); |
| SkASSERT(effect); |
| return sk_ref_sp(effect); |
| } |
| |
| static bool all_channels_equal(const SkColor4f& c) { |
| return c.fR == c.fG && c.fR == c.fB; |
| } |
| #endif // SK_ENABLE_SKSL |
| |
| sk_sp<SkShader> SkGainmapShader::Make(sk_sp<SkImage> baseImage, |
| const SkRect& baseRect, |
| const SkSamplingOptions& baseSamplingOptions, |
| sk_sp<SkImage> gainmapImage, |
| const SkRect& gainmapRect, |
| const SkSamplingOptions& gainmapSamplingOptions, |
| const SkGainmapInfo& gainmapInfo, |
| const SkRect& dstRect, |
| float dstHdrRatio, |
| sk_sp<SkColorSpace> dstColorSpace) { |
| #ifdef SK_ENABLE_SKSL |
| 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(); |
| if (!dstColorSpace) { |
| dstColorSpace = SkColorSpace::MakeSRGB(); |
| } |
| |
| // 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); |
| |
| // Create a color filter to transform from the color space in which the gainmap is applied to |
| // the destination color space. |
| auto colorXformGainmapToDst = |
| SkColorFilterPriv::MakeColorSpaceXform(gainmapMathColorSpace, dstColorSpace); |
| |
| // The base image shader will convert into the color space in which the gainmap is applied. |
| const SkMatrix baseRectToDstRect = SkMatrix::RectToRect(baseRect, dstRect); |
| auto baseImageShader = baseImage->makeRawShader(baseSamplingOptions, &baseRectToDstRect) |
| ->makeWithColorFilter(colorXformSdrToGainmap); |
| |
| // The gainmap image shader will ignore any color space that the gainmap has. |
| const SkMatrix gainmapRectToDstRect = SkMatrix::RectToRect(gainmapRect, dstRect); |
| auto gainmapImageShader = |
| gainmapImage->makeRawShader(gainmapSamplingOptions, &gainmapRectToDstRect); |
| |
| // Create the shader to apply the gainmap. |
| sk_sp<SkShader> gainmapMathShader; |
| { |
| SkRuntimeShaderBuilder builder(gainmap_apply_effect()); |
| const SkColor4f logRatioMin({gainmapInfo.fLogRatioMin.fR, |
| gainmapInfo.fLogRatioMin.fG, |
| gainmapInfo.fLogRatioMin.fB, |
| 1.f}); |
| const SkColor4f logRatioMax({gainmapInfo.fLogRatioMax.fR, |
| gainmapInfo.fLogRatioMax.fG, |
| gainmapInfo.fLogRatioMax.fB, |
| 1.f}); |
| const float Wunclamped = |
| (sk_float_log(dstHdrRatio) - sk_float_log(gainmapInfo.fHdrRatioMin)) / |
| (sk_float_log(gainmapInfo.fHdrRatioMax) - sk_float_log(gainmapInfo.fHdrRatioMin)); |
| const float W = std::max(std::min(Wunclamped, 1.f), 0.f); |
| const int noGamma = |
| gainmapInfo.fGainmapGamma.fR == 1.f && |
| gainmapInfo.fGainmapGamma.fG == 1.f && |
| gainmapInfo.fGainmapGamma.fB == 1.f; |
| const int singleChannel = |
| all_channels_equal(gainmapInfo.fGainmapGamma) && |
| all_channels_equal(gainmapInfo.fLogRatioMin) && |
| all_channels_equal(gainmapInfo.fLogRatioMax) && |
| gainmapImage->colorType() == kGray_8_SkColorType; |
| builder.child("base") = baseImageShader; |
| builder.child("gainmap") = gainmapImageShader; |
| builder.uniform("logRatioMin") = logRatioMin; |
| builder.uniform("logRatioMax") = logRatioMax; |
| builder.uniform("gainmapGamma") = gainmapInfo.fGainmapGamma; |
| builder.uniform("epsilonSdr") = gainmapInfo.fEpsilonSdr; |
| builder.uniform("epsilonHdr") = gainmapInfo.fEpsilonHdr; |
| builder.uniform("noGamma") = noGamma; |
| builder.uniform("singleChannel") = singleChannel; |
| builder.uniform("W") = W; |
| gainmapMathShader = builder.makeShader(); |
| SkASSERT(gainmapMathShader); |
| } |
| |
| // Return a shader that will apply the gainmap and then convert to the destination color space. |
| return gainmapMathShader->makeWithColorFilter(colorXformGainmapToDst); |
| #else |
| // This shader is currently only implemented using SkSL. |
| return nullptr; |
| #endif |
| } |