SkHighContrastFilter Struct Reference

#include <SkHighContrastFilter.h>

Static Public Member Functions
static sk_sp< SkColorFilter >	Make (const SkHighContrastConfig &config)

Detailed Description

Color filter that provides transformations to improve contrast for users with low vision.

Applies the following transformations in this order. Each of these can be configured using SkHighContrastConfig.

• Conversion to grayscale
• Color inversion (either in RGB or HSL space)
• Increasing the resulting contrast.

Calling SkHighContrastFilter::Make will return nullptr if the config is not valid, e.g. if you try to call it with a contrast outside the range of -1.0 to 1.0.

Definition at line 79 of file SkHighContrastFilter.h.

Member Function Documentation

Make()

sk_sp< SkColorFilter > SkHighContrastFilter::Make ( const SkHighContrastConfig &  config )

static

Definition at line 23 of file SkHighContrastFilter.cpp.

                                                                                  {
    if (!config.isValid()) {
        return nullptr;
    }
 
    struct Uniforms { float grayscale, invertStyle, contrast; };
 
    // 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),
    };
 
    const SkRuntimeEffect* highContrastEffect =
            GetKnownRuntimeEffect(SkKnownRuntimeEffects::StableKey::kHighContrast);
 
    const SkAlphaType kUnpremul = kUnpremul_SkAlphaType;
    return SkColorFilterPriv::WithWorkingFormat(
            highContrastEffect->makeColorFilter(SkData::MakeWithCopy(&uniforms,sizeof(uniforms))),
            &SkNamedTransferFn::kLinear,
            /* gamut= */ nullptr,           // use the dst gamut
            &kUnpremul);
}

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The documentation for this struct was generated from the following files:

• third_party/skia/include/effects/SkHighContrastFilter.h
• third_party/skia/src/effects/SkHighContrastFilter.cpp