26 lines
842 B
TypeScript
26 lines
842 B
TypeScript
export function colorIsDark(color: string | undefined) {
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if (typeof color === 'undefined') {
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return true // Defaults to dark
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}
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if (color === '#' || color === '') {
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return true // Defaults to dark
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}
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if (color.substring(0, 1) !== '#') {
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color = '#' + color
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}
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const rgb = parseInt(color.substring(1, 7), 16) // convert rrggbb to decimal
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const r = (rgb >> 16) & 0xff // extract red
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const g = (rgb >> 8) & 0xff // extract green
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const b = (rgb >> 0) & 0xff // extract blue
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// this is a quick and dirty implementation of the WCAG 3.0 APCA color contrast formula
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// see: https://gist.github.com/Myndex/e1025706436736166561d339fd667493#andys-shortcut-to-luminance--lightness
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const Ys = Math.pow(r/255.0,2.2) * 0.2126 +
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Math.pow(g/255.0,2.2) * 0.7152 +
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Math.pow(b/255.0,2.2) * 0.0722
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return Math.pow(Ys,0.678) >= 0.5
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} |