forked from Fediversity/fediversity.eu
56 lines
1.6 KiB
JavaScript
56 lines
1.6 KiB
JavaScript
var shorterNames = require('./shorter-css-color-names');
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var REGEX = {
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whitespace: /\s+/g,
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urlHexPairs: /%[\dA-F]{2}/g,
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quotes: /"/g,
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}
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function collapseWhitespace(str) {
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return str.trim().replace(REGEX.whitespace, ' ');
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}
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function dataURIPayload(string) {
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return encodeURIComponent(string)
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.replace(REGEX.urlHexPairs, specialHexEncode);
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}
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// `#` gets converted to `%23`, so quite a few CSS named colors are shorter than
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// their equivalent URL-encoded hex codes.
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function colorCodeToShorterNames(string) {
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Object.keys(shorterNames).forEach(function(key) {
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if (shorterNames[key].test(string)) {
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string = string.replace(shorterNames[key], key);
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}
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});
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return string;
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}
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function specialHexEncode(match) {
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switch (match) { // Browsers tolerate these characters, and they're frequent
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case '%20': return ' ';
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case '%3D': return '=';
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case '%3A': return ':';
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case '%2F': return '/';
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default: return match.toLowerCase(); // compresses better
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}
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}
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function svgToTinyDataUri(svgString) {
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if (typeof svgString !== 'string') {
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throw new TypeError('Expected a string, but received ' + typeof svgString);
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}
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// Strip the Byte-Order Mark if the SVG has one
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if (svgString.charCodeAt(0) === 0xfeff) { svgString = svgString.slice(1) }
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var body = colorCodeToShorterNames(collapseWhitespace(svgString))
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.replace(REGEX.quotes, "'");
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return 'data:image/svg+xml,' + dataURIPayload(body);
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}
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svgToTinyDataUri.toSrcset = function toSrcset(svgString) {
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return svgToTinyDataUri(svgString).replace(/ /g, '%20');
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}
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module.exports = svgToTinyDataUri;
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