23 lines
618 B
JavaScript
23 lines
618 B
JavaScript
function limit_color(r){
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if (r > 255) return 255;
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else if (r < 0) return 0;
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return r;
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}
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export function lighten_darken_color(col, amt) {
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let usePound = false;
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if (col[0] == "#") {
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col = col.slice(1);
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usePound = true;
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}
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let num = parseInt(col,16);
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let r = limit_color((num >> 16) + amt);
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let b = limit_color(((num >> 8) & 0x00FF) + amt);
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let g = limit_color((num & 0x0000FF) + amt);
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return (usePound?"#":"") + (g | (b << 8) | (r << 16)).toString(16);
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}
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export function is_valid_color(string) {
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// https://stackoverflow.com/a/8027444/6495043
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return /(^#[0-9A-F]{6}$)|(^#[0-9A-F]{3}$)/i.test(string);
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} |