33 lines
1.0 KiB
JavaScript
33 lines
1.0 KiB
JavaScript
/* Given a backgorund color, should you write on it in black or white ?
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Taken from http://stackoverflow.com/questions/3942878/how-to-decide-font-color-in-white-or-black-depending-on-background-color#comment61936401_3943023
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*/
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export default function(color, simple) {
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let r = hexToR(color),
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g = hexToG(color),
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b = hexToB(color)
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if (simple) { // The YIQ formula
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return ((r * 0.299 + g * 0.587 + b * 0.114) > 128) ?
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'#000000' : '#ffffff'
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} // else complex formula
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let
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uicolors = [ r / 255, g / 255, b / 255 ],
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c = uicolors.map(c =>
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c <= 0.03928 ?
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c / 12.92 :
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Math.pow((c + 0.055) / 1.055, 2.4)
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),
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L = 0.2126 * c[0] + 0.7152 * c[1] + 0.0722 * c[2]
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return (L > 0.179) ? '#000000' : '#ffffff'
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}
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/* Hex to RGB conversion:
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* http://www.javascripter.net/faq/hextorgb.htm
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*/
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let cutHex = h => (h.charAt(0) == '#') ? h.substring(1, 7) : h,
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hexToR = h => parseInt((cutHex(h)).substring(0, 2),16),
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hexToG = h => parseInt((cutHex(h)).substring(2, 4),16),
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hexToB = h => parseInt((cutHex(h)).substring(4, 6),16)
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