element-web/src/utils/colour.js
Michael Telatynski 657a11de83 Fix /rainbowme and /rainbow breaking apart utf-16 emoji
Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>
2019-07-25 19:25:28 +01:00

67 lines
1.8 KiB
JavaScript

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