67 lines
1.8 KiB
JavaScript
67 lines
1.8 KiB
JavaScript
/*
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Copyright 2019 Michael Telatynski <7t3chguy@gmail.com>
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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export function hueToRGB(h, s, l) {
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const c = s * (1 - Math.abs(2 * l - 1));
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const x = c * (1 - Math.abs((h / 60) % 2 - 1));
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const m = l - c / 2;
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let r = 0;
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let g = 0;
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let b = 0;
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if (0 <= h && h < 60) {
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r = c;
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g = x;
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b = 0;
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} else if (60 <= h && h < 120) {
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r = x;
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g = c;
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b = 0;
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} else if (120 <= h && h < 180) {
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r = 0;
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g = c;
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b = x;
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} else if (180 <= h && h < 240) {
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r = 0;
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g = x;
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b = c;
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} else if (240 <= h && h < 300) {
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r = x;
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g = 0;
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b = c;
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} else if (300 <= h && h < 360) {
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r = c;
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g = 0;
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b = x;
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}
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return [Math.round((r + m) * 255), Math.round((g + m) * 255), Math.round((b + m) * 255)];
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}
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export function textToHtmlRainbow(str) {
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const frequency = 360 / str.length;
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return Array.from(str).map((c, i) => {
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const [r, g, b] = hueToRGB(i * frequency, 1.0, 0.5);
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return '<font color="#' +
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r.toString(16).padStart(2, "0") +
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g.toString(16).padStart(2, "0") +
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b.toString(16).padStart(2, "0") +
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'">' + c + '</font>';
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}).join("");
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}
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