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61 lines
1.4 KiB
61 lines
1.4 KiB
// HSL to RGB converter. Both methods adapted from: |
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// http://mjijackson.com/2008/02/rgb-to-hsl-and-rgb-to-hsv-color-model-conversion-algorithms-in-javascript |
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function hslToRgb(h, s, l) { |
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var r, g, b; |
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// normalize hue orientation b/w 0 and 360 degrees |
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h = h % 360; |
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if (h < 0) |
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h += 360; |
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h = ~~h / 360; |
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if (s < 0) |
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s = 0; |
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else if (s > 100) |
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s = 100; |
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s = ~~s / 100; |
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if (l < 0) |
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l = 0; |
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else if (l > 100) |
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l = 100; |
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l = ~~l / 100; |
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if (s === 0) { |
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r = g = b = l; // achromatic |
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} else { |
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var q = l < 0.5 ? |
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l * (1 + s) : |
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l + s - l * s; |
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var p = 2 * l - q; |
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r = hueToRgb(p, q, h + 1/3); |
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g = hueToRgb(p, q, h); |
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b = hueToRgb(p, q, h - 1/3); |
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} |
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return [~~(r * 255), ~~(g * 255), ~~(b * 255)]; |
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} |
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function hueToRgb(p, q, t) { |
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if (t < 0) t += 1; |
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if (t > 1) t -= 1; |
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if (t < 1/6) return p + (q - p) * 6 * t; |
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if (t < 1/2) return q; |
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if (t < 2/3) return p + (q - p) * (2/3 - t) * 6; |
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return p; |
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} |
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function shortenHsl(hue, saturation, lightness) { |
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var asRgb = hslToRgb(hue, saturation, lightness); |
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var redAsHex = asRgb[0].toString(16); |
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var greenAsHex = asRgb[1].toString(16); |
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var blueAsHex = asRgb[2].toString(16); |
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return '#' + |
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((redAsHex.length == 1 ? '0' : '') + redAsHex) + |
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((greenAsHex.length == 1 ? '0' : '') + greenAsHex) + |
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((blueAsHex.length == 1 ? '0' : '') + blueAsHex); |
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} |
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module.exports = shortenHsl;
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