feat(monospace): build CSS with embedded woff2 base64

src/main/ExportCss.js

@@ -0,0 +1,25 @@
+'use strict';
+
+const { FAMILY_BY_KEY } = require('./settings/monospaceSettings');
+
+function buildFontFaceBlock(family, woff2Bytes) {
+  const safeFamily = family.replace(/'/g, "\\'");
+  const b64 = Buffer.from(woff2Bytes).toString('base64');
+  return `@font-face {
+  font-family: '${safeFamily}';
+  src: url(data:font/woff2;base64,${b64}) format('woff2');
+  font-weight: 100 900;
+  font-style: normal;
+  font-display: swap;
+}`;
+}
+
+function buildExportCss(settings, { woff2 } = {}) {
+  const family = (settings && FAMILY_BY_KEY[settings.monospaceFont]) || 'JetBrains Mono';
+  const ligatures = !!(settings && settings.monospaceLigatures === true);
+  const face = buildFontFaceBlock(family, woff2 || Buffer.alloc(0));
+  const feature = ligatures ? `code, pre, kbd, samp { font-feature-settings: 'liga' 1, 'calt' 1; }` : '';
+  return [face, feature].filter(Boolean).join('\n\n');
+}
+
+module.exports = { buildExportCss, buildFontFaceBlock };