allow overriding theme fonts

src/routes/api/fonts.js

@@ -0,0 +1,33 @@
+const optionService = require('../../services/options');
+
+function getFontCss(req, res) {
+    res.setHeader('Content-Type', 'text/css');
+
+    if (!optionService.getOptionBool('overrideThemeFonts')) {
+        res.send('');
+
+        return;
+    }
+
+    const optionsMap = optionService.getOptionsMap();
+
+    // using body to be more specific than themes' :root
+    res.send(`
+body {
+    --main-font-family: ${optionsMap.mainFontFamily};
+    --main-font-size: ${optionsMap.mainFontSize}%;
+     
+    --tree-font-family: ${optionsMap.treeFontFamily};
+    --tree-font-size: ${optionsMap.treeFontSize}%; 
+    
+    --detail-font-family: ${optionsMap.detailFontFamily};
+    --detail-font-size: ${optionsMap.detailFontSize}%;
+    
+    --monospace-font-family: ${optionsMap.monospaceFontFamily};
+    --monospace-font-size: ${optionsMap.monospaceFontSize};
+}`);
+}
+
+module.exports = {
+    getFontCss
+};

src/routes/api/options.js

@@ -17,8 +17,13 @@ const ALLOWED_OPTIONS = new Set([
     'syncProxy',
     'hoistedNoteId',
     'mainFontSize',
+    'mainFontFamily',
     'treeFontSize',
+    'treeFontFamily',
     'detailFontSize',
+    'detailFontFamily',
+    'monospaceFontSize',
+    'monospaceFontFamily',
     'openTabs',
     'noteInfoWidget',
     'attributesWidget',
@@ -44,7 +49,8 @@ const ALLOWED_OPTIONS = new Set([
     'headingStyle',
     'autoCollapseNoteTree',
     'autoReadonlySizeText',
-    'autoReadonlySizeCode'
+    'autoReadonlySizeCode',
+    'overrideThemeFonts'
 ]);
 
 function getOptions() {

src/routes/routes.js

@@ -38,6 +38,7 @@ const similarNotesRoute = require('./api/similar_notes');
 const keysRoute = require('./api/keys');
 const backendLogRoute = require('./api/backend_log');
 const statsRoute = require('./api/stats');
+const fontsRoute = require('./api/fonts');
 
 const log = require('../services/log');
 const express = require('express');
@@ -326,6 +327,8 @@ function register(app) {
 
     apiRoute(POST, '/api/delete-notes-preview', notesApiRoute.getDeleteNotesPreview);
 
+    route(GET, '/api/fonts', [auth.checkApiAuthOrElectron], fontsRoute.getFontCss);
+
     app.use('', router);
 }