wcag2ContrastRatio - multiple declarations

Function wcag2ContrastRatio

Computes the WCAG 2 contrast ratio between two linear-light sRGB colors.

Wcag2Measurement!T wcag2ContrastRatio(T)(
  LinearSRgb!T first,
  LinearSRgb!T second
) pure nothrow @nogc @safe;

Use this when both colors have already been decoded to linear light and any alpha has been resolved. Components must be finite and from 0 through 1 inclusive. Invalid input produces an invalid measurement. No hidden conversion, clipping, gamut mapping, alpha compositing, or threshold policy is applied.

Parameters

NameDescription
first First normalized linear-light sRGB color.
second Second normalized linear-light sRGB color.

Returns

A valid WCAG 2 contrast ratio, or an invalid measurement.

Standards

W3C WCAG 2.2 contrast ratio.

Example

import color.rgb : LinearSRgbd;

const contrast = LinearSRgbd(0, 0, 0).wcag2ContrastRatio(
    LinearSRgbd(1, 1, 1)
);

assert(contrast.valid);
assert(contrast.value == 21);

Function wcag2ContrastRatio

Computes the WCAG 2 contrast ratio between two encoded-sRGB colors.

Wcag2Measurement!T wcag2ContrastRatio(T)(
  SRgb!T first,
  SRgb!T second
) pure nothrow @nogc @safe;

Use this after any alpha has been resolved. Both colors must contain finite normalized components from 0 through 1 inclusive. Invalid input produces an invalid measurement. No clipping, gamut mapping, alpha compositing, or accessibility-threshold classification is applied.

Parameters

NameDescription
first First normalized encoded-sRGB color.
second Second normalized encoded-sRGB color.

Returns

A valid WCAG 2 contrast ratio, or an invalid measurement.

Standards

W3C WCAG 2.2 contrast ratio.

Example

Black against white has the maximum WCAG 2 sRGB contrast ratio. 

import color.rgb :
    SRgbd;

const contrast =
    SRgbd(0, 0, 0).wcag2ContrastRatio(
        SRgbd(1, 1, 1)
    );

assert(contrast.valid);
assert(
    contrast.value > 20.999999 &&
    contrast.value < 21.000001
);