@deathbeds/jupyterlab-fonts/lib/util.js

import { FONT_FORMATS, FontFormat } from '.';
/* below from https://gist.github.com/viljamis/c4016ff88745a0846b94 */
const CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
export function base64Encode(str) {
    let out = '';
    let i = 0;
    let len = str.length;
    let c1;
    let c2;
    let c3;
    // tslint:disable
    while (i < len) {
        c1 = str.charCodeAt(i++) & 0xff;
        if (i === len) {
            out += CHARS.charAt(c1 >> 2);
            out += CHARS.charAt((c1 & 0x3) << 4);
            out += '==';
            break;
        }
        c2 = str.charCodeAt(i++);
        if (i === len) {
            out += CHARS.charAt(c1 >> 2);
            out += CHARS.charAt(((c1 & 0x3) << 4) | ((c2 & 0xf0) >> 4));
            out += CHARS.charAt((c2 & 0xf) << 2);
            out += '=';
            break;
        }
        c3 = str.charCodeAt(i++);
        out += CHARS.charAt(c1 >> 2);
        out += CHARS.charAt(((c1 & 0x3) << 4) | ((c2 & 0xf0) >> 4));
        out += CHARS.charAt(((c2 & 0xf) << 2) | ((c3 & 0xc0) >> 6));
        out += CHARS.charAt(c3 & 0x3f);
    }
    // tslint:enable
    return out;
}
export async function dataURISrc(url, format = FontFormat.woff2) {
    const pre = `data:${FONT_FORMATS[format]};charset=utf-8;base64`;
    const base64Font = base64Encode(await getBinary(url));
    const post = `format('${format}')`;
    const src = `url('${pre},${base64Font}') ${post}`;
    return src;
}
export function getBinary(url) {
    return new Promise((resolve, reject) => {
        const xhr = new XMLHttpRequest();
        xhr.open('GET', url, true);
        xhr.overrideMimeType('text/plain; charset=x-user-defined');
        xhr.onreadystatechange = () => {
            if (xhr.readyState === 4 && xhr.status === 200) {
                resolve(xhr.responseText);
            }
        };
        xhr.send();
    });
}
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