| /* |
| * 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 "include/core/SkString.h" |
| #include "include/effects/SkHighContrastFilter.h" |
| #include "include/effects/SkRuntimeEffect.h" |
| #include "include/private/SkTPin.h" |
| #include "src/core/SkRuntimeEffectPriv.h" |
| |
| sk_sp<SkColorFilter> SkHighContrastFilter::Make(const SkHighContrastConfig& config) { |
| if (!config.isValid()) { |
| return nullptr; |
| } |
| |
| struct Uniforms { float grayscale, invertStyle, contrast; }; |
| |
| static SkRuntimeEffect* effect = []{ |
| SkString code{R"( |
| uniform shader input; |
| uniform half grayscale, invertStyle, contrast; |
| )"}; |
| code += kRGB_to_HSL_sksl; |
| code += kHSL_to_RGB_sksl; |
| code += R"( |
| half4 main() { |
| half4 c = sample(input); // linear unpremul RGBA in dst gamut. |
| if (grayscale == 1) { |
| c.rgb = dot(half3(0.2126, 0.7152, 0.0722), c.rgb).rrr; |
| } |
| if (invertStyle == 1/*brightness*/) { |
| c.rgb = 1 - c.rgb; |
| } else if (invertStyle == 2/*lightness*/) { |
| c.rgb = rgb_to_hsl(c.rgb); |
| c.b = 1 - c.b; |
| c.rgb = hsl_to_rgb(c.rgb); |
| } |
| c.rgb = mix(half3(0.5), c.rgb, contrast); |
| return half4(saturate(c.rgb), c.a); |
| } |
| )"; |
| |
| auto [effect, err] = SkRuntimeEffect::Make(code); |
| if (!err.isEmpty()) { |
| SkDebugf("%s\n%s\n", code.c_str(), err.c_str()); |
| } |
| SkASSERT(effect && err.isEmpty()); |
| return effect.release(); |
| }(); |
| |
| // A contrast setting of exactly +1 would divide by zero (1+c)/(1-c), so pull in to +1-ε. |
| // I'm not exactly sure why we've historically pinned -1 up to -1+ε, maybe just symmetry? |
| float c = SkTPin(config.fContrast, |
| -1.0f + FLT_EPSILON, |
| +1.0f - FLT_EPSILON); |
| |
| Uniforms uniforms = { |
| config.fGrayscale ? 1.0f : 0.0f, |
| (float)config.fInvertStyle, // 0.0f for none, 1.0f for brightness, 2.0f for lightness |
| (1+c)/(1-c), |
| }; |
| |
| sk_sp<SkColorFilter> input = nullptr; |
| skcms_TransferFunction linear = SkNamedTransferFn::kLinear; |
| SkAlphaType unpremul = kUnpremul_SkAlphaType; |
| return SkColorFilters::WithWorkingFormat( |
| effect->makeColorFilter(SkData::MakeWithCopy(&uniforms,sizeof(uniforms)), &input, 1), |
| &linear, nullptr/*use dst gamut*/, &unpremul); |
| } |
| |