86 lines
2.2 KiB
JavaScript
86 lines
2.2 KiB
JavaScript
const AmiColour = (() => {
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const readThres = 168;
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const lumiRed = .299;
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const lumiGreen = .587;
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const lumiBlue = .114;
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const pub = {};
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const extractRGB = raw => [
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(raw >> 16) & 0xFF,
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(raw >> 8) & 0xFF,
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raw & 0xFF,
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];
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const luminance = raw => {
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const rgb = extractRGB(raw);
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return rgb[0] * lumiRed
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+ rgb[1] * lumiGreen
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+ rgb[2] * lumiBlue;
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};
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const weightedNumber = (num1, num2, weight) => {
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weight = Math.min(1, Math.max(0, weight));
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return Math.round((num1 * weight) + (num2 * (1 - weight)));
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};
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const weighted = (raw1, raw2, weight) => {
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const rgb1 = extractRGB(raw1),
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rgb2 = extractRGB(raw2);
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return (weightedNumber(rgb1[0], rgb2[0], weight) << 16)
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| (weightedNumber(rgb1[1], rgb2[1], weight) << 8)
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| weightedNumber(rgb1[2], rgb2[2], weight);
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};
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pub.extractRGB = extractRGB;
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pub.weightedNumber = weightedNumber;
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pub.luminance = luminance;
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pub.weighted = weighted;
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pub.text = raw => luminance(raw) > readThres ? 0 : 0xFFFFFF;
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pub.shaded = (raw, offset) => {
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if(offset == 0)
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return raw;
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let dir = 0xFFFFFF;
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if(offset < 0) {
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dir = 0;
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offset *= -1;
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}
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return weighted(dir, raw, offset);
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};
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pub.hexByte = raw => {
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let str = raw.toString(16).substring(0, 2);
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return str.length < 2
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? `0${str}` : str;
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};
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pub.hex = raw => {
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let str = raw.toString(16).substring(0, 6);
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if(str.length < 6)
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str = '000000'.substring(str.length) + str;
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return `#${str}`;
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};
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pub.fromHex = str => {
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while(str.substring(0, 1) === '#')
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str = str.substring(1);
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str = str.substring(0, 6);
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if(str.length === 3)
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str = str.substring(0, 1) + str.substring(0, 1)
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+ str.substring(1, 2) + str.substring(1, 2)
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+ str.substring(2, 3) + str.substring(2, 3);
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if(str.length !== 6)
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throw 'not a valid hex string';
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return parseInt(str, 16);
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};
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return pub;
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})();
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