Electron Spellcheck (WIP PR)

electron_app/package.json

@@ -7,8 +7,13 @@
   "author": "Vector Creations Ltd.",
   "dependencies": {
     "auto-launch": "^5.0.1",
+    "electron": "^3.0.9",
     "electron-window-state": "^4.1.0",
     "minimist": "^1.2.0",
-    "png-to-ico": "^1.0.2"
+    "os": "^0.1.1",
+    "os-locale": "^3.0.1",
+    "png-to-ico": "^1.0.2",
+    "semver": "^5.6.0",
+    "spellchecker": "^3.5.0"
   }
 }

electron_app/src/spellcheck.js

@@ -0,0 +1,175 @@
+/* global require, process, _ */
+
+/* eslint-disable strict */
+const electron = require('electron');
+const osLocale = require('os-locale');
+const os = require('os');
+const semver = require('semver');
+const spellchecker = require('spellchecker');
+
+const { remote, webFrame } = electron;
+
+// `remote.require` since `Menu` is a main-process module.
+const buildEditorContextMenu = remote.require('electron-editor-context-menu');
+
+const EN_VARIANT = /^en/;
+
+// Prevent the spellchecker from showing contractions as errors.
+const ENGLISH_SKIP_WORDS = [
+  'ain',
+  'couldn',
+  'didn',
+  'doesn',
+  'hadn',
+  'hasn',
+  'mightn',
+  'mustn',
+  'needn',
+  'oughtn',
+  'shan',
+  'shouldn',
+  'wasn',
+  'weren',
+  'wouldn',
+];
+
+function setupLinux(locale) {
+  if (process.env.HUNSPELL_DICTIONARIES || locale !== 'en_US') {
+    // apt-get install hunspell-<locale> can be run for easy access
+    //   to other dictionaries
+    const location = process.env.HUNSPELL_DICTIONARIES || '/usr/share/hunspell';
+
+    window.log.info(
+      'Detected Linux. Setting up spell check with locale',
+      locale,
+      'and dictionary location',
+      location
+    );
+    spellchecker.setDictionary(locale, location);
+  } else {
+    window.log.info(
+      'Detected Linux. Using default en_US spell check dictionary'
+    );
+  }
+}
+
+function setupWin7AndEarlier(locale) {
+  if (process.env.HUNSPELL_DICTIONARIES || locale !== 'en_US') {
+    const location = process.env.HUNSPELL_DICTIONARIES;
+
+    window.log.info(
+      'Detected Windows 7 or below. Setting up spell-check with locale',
+      locale,
+      'and dictionary location',
+      location
+    );
+    spellchecker.setDictionary(locale, location);
+  } else {
+    window.log.info(
+      'Detected Windows 7 or below. Using default en_US spell check dictionary'
+    );
+  }
+}
+
+// We load locale this way and not via app.getLocale() because this call returns
+//   'es_ES' and not just 'es.' And hunspell requires the fully-qualified locale.
+const locale = osLocale.sync().replace('-', '_');
+
+// The LANG environment variable is how node spellchecker finds its default language:
+//   https://github.com/atom/node-spellchecker/blob/59d2d5eee5785c4b34e9669cd5d987181d17c098/lib/spellchecker.js#L29
+if (!process.env.LANG) {
+  process.env.LANG = locale;
+}
+
+if (process.platform === 'linux') {
+  setupLinux(locale);
+} else if (process.platform === 'windows' && semver.lt(os.release(), '8.0.0')) {
+  setupWin7AndEarlier(locale);
+} else {
+  // OSX and Windows 8+ have OS-level spellcheck APIs
+  window.log.info(
+    'Using OS-level spell check API with locale',
+    process.env.LANG
+  );
+}
+
+const simpleChecker = {
+  spellCheck(text) {
+    return !this.isMisspelled(text);
+  },
+  isMisspelled(text) {
+    const misspelled = spellchecker.isMisspelled(text);
+
+    // The idea is to make this as fast as possible. For the many, many calls which
+    //   don't result in the red squiggly, we minimize the number of checks.
+    if (!misspelled) {
+      return false;
+    }
+
+    // Only if we think we've found an error do we check the locale and skip list.
+    if (locale.match(EN_VARIANT) && _.contains(ENGLISH_SKIP_WORDS, text)) {
+      return false;
+    }
+
+    return true;
+  },
+  getSuggestions(text) {
+    return spellchecker.getCorrectionsForMisspelling(text);
+  },
+  add(text) {
+    spellchecker.add(text);
+  },
+};
+
+const dummyChecker = {
+  spellCheck() {
+    return true;
+  },
+  isMisspelled() {
+    return false;
+  },
+  getSuggestions() {
+    return [];
+  },
+  add() {
+    // nothing
+  },
+};
+
+// set the languange based on the locale
+const osLanguage = locale.replace('_','-');
+
+window.spellChecker = simpleChecker;
+window.disableSpellCheck = () => {
+  window.removeEventListener('contextmenu', spellCheckHandler);
+  webFrame.setSpellCheckProvider(osLanguage, dummyChecker);
+};
+
+window.enableSpellCheck = () => {
+  webFrame.setSpellCheckProvider(osLanguage,simpleChecker);
+  window.addEventListener('contextmenu', spellCheckHandler);
+};
+
+const spellCheckHandler = e => {
+  // Only show the context menu in text editors.
+  if (!e.target.closest('textarea, input, [contenteditable="true"]')) {
+    return;
+  }
+
+  const selectedText = window.getSelection().toString();
+  const isMisspelled = selectedText && simpleChecker.isMisspelled(selectedText);
+  const spellingSuggestions =
+    isMisspelled && simpleChecker.getSuggestions(selectedText).slice(0, 5);
+  const menu = buildEditorContextMenu({
+    isMisspelled,
+    spellingSuggestions,
+  });
+
+  // The 'contextmenu' event is emitted after 'selectionchange' has fired
+  //   but possibly before the visible selection has changed. Try to wait
+  //   to show the menu until after that, otherwise the visible selection
+  //   will update after the menu dismisses and look weird.
+  setTimeout(() => {
+    menu.popup(remote.getCurrentWindow());
+  }, 30);
+};