Web Component Virtual Keyboard

ui/keyboard/resources/common.js

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-/**
- * @fileoverview A simple virtual keyboard implementation.
- */
-
-var KEY_MODE = 'key';
-var SHIFT_MODE = 'shift';
-var NUMBER_MODE = 'number';
-var SYMBOL_MODE = 'symbol';
-// TODO(bryeung): tear out all of this mode switching code
-var MODES = [KEY_MODE, SHIFT_MODE, NUMBER_MODE, SYMBOL_MODE];
-var currentMode = KEY_MODE;
-var enterShiftModeOnSpace = false;
-var MODE_CODES = {};
-var MODE_TRANSITIONS = {};
-
-MODE_CODES[KEY_MODE] = 0;
-MODE_CODES[SHIFT_MODE] = 1;
-MODE_CODES[NUMBER_MODE] = 2;
-MODE_CODES[SYMBOL_MODE] = 3;
-
-MODE_TRANSITIONS[KEY_MODE + SHIFT_MODE] = SHIFT_MODE;
-MODE_TRANSITIONS[KEY_MODE + NUMBER_MODE] = NUMBER_MODE;
-MODE_TRANSITIONS[SHIFT_MODE + SHIFT_MODE] = KEY_MODE;
-MODE_TRANSITIONS[SHIFT_MODE + NUMBER_MODE] = NUMBER_MODE;
-MODE_TRANSITIONS[NUMBER_MODE + SHIFT_MODE] = SYMBOL_MODE;
-MODE_TRANSITIONS[NUMBER_MODE + NUMBER_MODE] = KEY_MODE;
-MODE_TRANSITIONS[SYMBOL_MODE + SHIFT_MODE] = NUMBER_MODE;
-MODE_TRANSITIONS[SYMBOL_MODE + NUMBER_MODE] = KEY_MODE;
-
-var KEYBOARDS = {};
-
-/**
- * The long-press delay in milliseconds before long-press handler is invoked.
- * @type {number}
- */
-var LONGPRESS_DELAY_MSEC = 500;
-
-/**
- * The repeat delay in milliseconds before a key starts repeating. Use the same
- * rate as Chromebook. (See chrome/browser/chromeos/language_preferences.cc)
- * @type {number}
- */
-var REPEAT_DELAY_MSEC = 500;
-
-/**
- * The repeat interval or number of milliseconds between subsequent keypresses.
- * Use the same rate as Chromebook.
- * @type {number}
- */
-var REPEAT_INTERVAL_MSEC = 50;
-
-/**
- * The keyboard layout name currently in use.
- * @type {string}
- */
-var currentKeyboardLayout = 'us';
-
-/**
- * A structure to track the currently repeating key on the keyboard.
- */
-var repeatKey = {
-    /**
-     * The timer for the delay before repeating behaviour begins.
-     * @type {number|undefined}
-     */
-    timer: undefined,
-
-    /**
-     * The interval timer for issuing keypresses of a repeating key.
-     * @type {number|undefined}
-     */
-    interval: undefined,
-
-    /**
-     * The key which is currently repeating.
-     * @type {BaseKey|undefined}
-     */
-    key: undefined,
-
-    /**
-     * Cancel the repeat timers of the currently active key.
-     */
-    cancel: function() {
-      clearTimeout(this.timer);
-      clearInterval(this.interval);
-      this.timer = undefined;
-      this.interval = undefined;
-      this.key = undefined;
-    }
-};
-
-/**
- * Set the keyboard mode.
- * @param {string} mode The new mode.
- */
-function setMode(mode) {
-  currentMode = mode;
-
-  var rows = KEYBOARDS[currentKeyboardLayout]['rows'];
-  for (var i = 0; i < rows.length; ++i) {
-    rows[i].showMode(currentMode);
-  }
-}
-
-/**
- * Transition the mode according to the given transition.
- * @param {string} transition The transition to take.
- */
-function transitionMode(transition) {
-  setMode(MODE_TRANSITIONS[currentMode + transition]);
-}
-
-/**
- * Send the given key to chrome but don't update the keyboard state.
- */
-function sendKeyRaw(key) {
-  var keyIdentifier = key;
-
-  // Fix up some keys to their respective identifiers for convenience.
-  if (keyIdentifier == ' ') {
-    keyIdentifier = 'Spacebar';
-  }
-
-  var keyEvent = {
-    keyIdentifier: keyIdentifier
-  };
-  sendKeyEvent(keyEvent);
-}
-
-/**
- * Send the given key to chrome, via the experimental extension API.
- * Also updates the current keyboard state based on the current state and which
- * character was sent.
- * @param {string} keyIdentifier The key to send.
- */
-function sendKey(keyIdentifier) {
-  sendKeyRaw(keyIdentifier);
-
-  // Exit shift mode after pressing any key but space.
-  if (currentMode == SHIFT_MODE && keyIdentifier != 'Spacebar') {
-    transitionMode(SHIFT_MODE);
-  }
-  // Enter shift mode after typing a closing punctuation and then a space for a
-  // new sentence.
-  if (enterShiftModeOnSpace) {
-    enterShiftModeOnSpace = false;
-    if (currentMode != SHIFT_MODE && keyIdentifier == 'Spacebar') {
-      setMode(SHIFT_MODE);
-    }
-  }
-  if (currentMode != SHIFT_MODE &&
-      (keyIdentifier == '.' || keyIdentifier == '?' || keyIdentifier == '!')) {
-    enterShiftModeOnSpace = true;
-  }
-}
-
-/**
- * Add a child div element that represents the content of the given element.
- * A child div element that represents a text content is added if
- * opt_textContent is given. Otherwise a child element that represents an image
- * content is added. If the given element already has a child, the child element
- * is modified.
- * @param {Element} element The DOM Element to which the content is added.
- * @param {string} opt_textContent The text to be inserted.
- */
-function addContent(element, opt_textContent) {
-  if (element.childNodes.length > 0) {
-    var content = element.childNodes[0];
-    if (opt_textContent) {
-      content.textContent = opt_textContent;
-    }
-    return;
-  }
-
-  var content = document.createElement('div');
-  if (opt_textContent) {
-    content.textContent = opt_textContent;
-    content.className = 'text-key';
-  } else {
-    content.className = 'image-key';
-  }
-  element.appendChild(content);
-}
-
-/**
- * Set up the event handlers necessary to respond to mouse and touch events on
- * the virtual keyboard.
- * @param {BaseKey} key The BaseKey object corresponding to this key.
- * @param {Element} element The top-level DOM Element to set event handlers on.
- * @param {Object.<string, function()>} handlers The object that contains key
- *     event handlers in the following form.
- *
- *     { 'up': keyUpHandler,
- *       'down': keyDownHandler,
- *       'long': keyLongHandler }
- *
- *     keyDownHandler: Called when the key is pressed. This will be called
- *         repeatedly when holding a repeating key.
- *     keyUpHandler: Called when the key is released. This is only called
- *         once per actual key press.
- *     keyLongHandler: Called when the key is long-pressed for
- *         |LONGPRESS_DELAY_MSEC| milliseconds.
- *
- *     The object does not necessarily contain all the handlers above, but
- *     needs to contain at least one of them.
- */
-function setupKeyEventHandlers(key, element, handlers) {
-  var keyDownHandler = handlers['down'];
-  var keyUpHandler = handlers['up'];
-  var keyLongHandler = handlers['long'];
-  if (!(keyDownHandler || keyUpHandler || keyLongPressHandler)) {
-    throw new Error('Invalid handlers passed to setupKeyEventHandlers');
-  }
-
-  /**
-   * Handle a key down event on the virtual key.
-   * @param {UIEvent} evt The UI event which triggered the key down.
-   */
-  var downHandler = function(evt) {
-    // Prevent any of the system gestures from happening.
-    evt.preventDefault();
-
-    // Don't process a key down if the key is already down.
-    if (key.pressed) {
-      return;
-    }
-    key.pressed = true;
-    if (keyDownHandler) {
-      keyDownHandler();
-    }
-    repeatKey.cancel();
-
-    // Start a repeating timer if there is a repeat interval and a function to
-    // process key down events.
-    if (key.repeat && keyDownHandler) {
-      repeatKey.key = key;
-      // The timeout for the repeating timer occurs at
-      // REPEAT_DELAY_MSEC - REPEAT_INTERVAL_MSEC so that the interval
-      // function can handle all repeat keypresses and will get the first one
-      // at the correct time.
-      repeatKey.timer = setTimeout(function() {
-            repeatKey.timer = undefined;
-            repeatKey.interval = setInterval(function() {
-                  keyDownHandler();
-                }, REPEAT_INTERVAL_MSEC);
-          }, Math.max(0, REPEAT_DELAY_MSEC - REPEAT_INTERVAL_MSEC));
-    }
-
-    if (keyLongHandler) {
-      // Copy the currentTarget of event, which is neccessary because |evt| can
-      // be modified before |keyLongHandler| is called.
-      var evtCopy = {};
-      evtCopy.currentTarget = evt.currentTarget;
-      key.longPressTimer = setTimeout(function() {
-          keyLongHandler(evtCopy),
-          clearTimeout(key.longPressTimer);
-          delete key.longPressTimer;
-          key.pressed = false;
-        }, LONGPRESS_DELAY_MSEC);
-    }
-  };
-
-  /**
-   * Handle a key up event on the virtual key.
-   * @param {UIEvent} evt The UI event which triggered the key up.
-   */
-  var upHandler = function(evt) {
-    // Prevent any of the system gestures from happening.
-    evt.preventDefault();
-
-    // Reset long-press timer.
-    if (key.longPressTimer) {
-      clearTimeout(key.longPressTimer);
-      delete key.longPressTimer;
-    }
-
-    // If they key was not actually pressed do not send a key up event.
-    if (!key.pressed) {
-      return;
-    }
-    key.pressed = false;
-
-    // Cancel running repeat timer for the released key only.
-    if (repeatKey.key == key) {
-      repeatKey.cancel();
-    }
-
-    if (keyUpHandler) {
-      keyUpHandler();
-    }
-  };
-
-  // Setup mouse event handlers.
-  element.addEventListener('mousedown', downHandler);
-  element.addEventListener('mouseup', upHandler);
-
-  // Setup touch handlers.
-  element.addEventListener('touchstart', downHandler);
-  element.addEventListener('touchend', upHandler);
-}
-
-/**
- * Create closure for the sendKey function.
- * @param {string} key The key paramater to sendKey.
- * @return {function()} A function which calls sendKey(key).
- */
-function sendKeyFunction(key) {
-  return function() {
-    sendKey(key);
-  };
-}
-
-/**
- * Plain-old-data class to represent a character.
- * @param {string} display The HTML to be displayed.
- * @param {string} id The key identifier for this Character.
- * @constructor
- */
-function Character(display, id) {
-  this.display = display;
-  this.keyIdentifier = id;
-}
-
-/**
- * Convenience function to make the keyboard data more readable.
- * @param {string} display The display for the created Character.
- * @param {string} opt_id The id for the created Character.
- * @return {Character} A character that contains display and opt_id. If
- *     opt_id is omitted, display is used as the id.
- */
-function C(display, opt_id) {
-  var id = opt_id || display;
-  return new Character(display, id);
-}
-
-/**
- * An abstract base-class for all keys on the keyboard.
- * @constructor
- */
-function BaseKey() {}
-
-BaseKey.prototype = {
-  /**
-   * The cell type of this key.  Determines the background colour.
-   * @type {string}
-   */
-  cellType_: '',
-
-  /**
-   * If true, holding this key will issue repeat keypresses.
-   * @type {boolean}
-   */
-  repeat_: false,
-
-  /**
-   * Track the pressed state of the key. This is true if currently pressed.
-   * @type {boolean}
-   */
-  pressed_: false,
-
-  /**
-   * Get the repeat behaviour of the key.
-   * @return {boolean} True if the key will repeat.
-   */
-  get repeat() {
-    return this.repeat_;
-  },
-
-  /**
-   * Set the repeat behaviour of the key
-   * @param {boolean} repeat True if the key should repeat.
-   */
-  set repeat(repeat) {
-    this.repeat_ = repeat;
-  },
-
-  /**
-   * Get the pressed state of the key.
-   * @return {boolean} True if the key is currently pressed.
-   */
-  get pressed() {
-    return this.pressed_;
-  },
-
-  /**
-   * Set the pressed state of the key.
-   * @param {boolean} pressed True if the key is currently pressed.
-   */
-  set pressed(pressed) {
-    this.pressed_ = pressed;
-  },
-
-  /**
-   * Create the DOM elements for the given keyboard mode.  Must be overridden.
-   * @param {string} mode The keyboard mode to create elements for.
-   * @return {Element} The top-level DOM Element for the key.
-   */
-  makeDOM: function(mode) {
-    throw new Error('makeDOM not implemented in BaseKey');
-  },
-};
-
-/**
- * A simple key which displays Characters.
- * @param {Object} key The Character for KEY_MODE.
- * @param {Object} shift The Character for SHIFT_MODE.
- * @param {Object} num The Character for NUMBER_MODE.
- * @param {Object} symbol The Character for SYMBOL_MODE.
- * @param {string} className An optional class name for the key.
- * @constructor
- * @extends {BaseKey}
- */
-function Key(key, shift, num, symbol, className) {
-  this.modeElements_ = {};
-  this.cellType_ = '';
-  this.className_ = (className) ? 'key ' + className : 'key';
-
-  this.modes_ = {};
-  this.modes_[KEY_MODE] = key;
-  this.modes_[SHIFT_MODE] = shift;
-  this.modes_[NUMBER_MODE] = num;
-  this.modes_[SYMBOL_MODE] = symbol;
-}
-
-Key.prototype = {
-  __proto__: BaseKey.prototype,
-
-  /** @override */
-  makeDOM: function(mode) {
-    if (!this.modes_[mode]) {
-      return null;
-    }
-
-    this.modeElements_[mode] = document.createElement('div');
-    var element = this.modeElements_[mode];
-    element.className = this.className_;
-
-    addContent(element, this.modes_[mode].display);
-
-    setupKeyEventHandlers(this, element,
-        { 'up': sendKeyFunction(this.modes_[mode].keyIdentifier) });
-    return element;
-  }
-};
-
-/**
- * A key which displays an SVG image.
- * @param {string} className The class that provides the image.
- * @param {string} keyId The key identifier for the key.
- * @param {boolean} opt_repeat True if the key should repeat.
- * @constructor
- * @extends {BaseKey}
- */
-function SvgKey(className, keyId, opt_repeat) {
-  this.modeElements_ = {};
-  this.cellType_ = 'nc';
-  this.className_ = className;
-  this.keyId_ = keyId;
-  this.repeat_ = opt_repeat || false;
-}
-
-SvgKey.prototype = {
-  __proto__: BaseKey.prototype,
-
-  /** @override */
-  makeDOM: function(mode) {
-    this.modeElements_[mode] = document.createElement('div');
-    this.modeElements_[mode].className = 'key dark';
-    this.modeElements_[mode].classList.add(this.className_);
-    addContent(this.modeElements_[mode]);
-
-    // send the key event on key down if key repeat is enabled
-    var handler = this.repeat_ ? { 'down' : sendKeyFunction(this.keyId_) } :
-                                 { 'up' : sendKeyFunction(this.keyId_) };
-    setupKeyEventHandlers(this, this.modeElements_[mode], handler);
-
-    return this.modeElements_[mode];
-  }
-};
-
-/**
- * A Key that remains the same through all modes.
- * @param {string} className The class name for the key.
- * @param {string} content The display text for the key.
- * @param {string} keyId The key identifier for the key.
- * @constructor
- * @extends {BaseKey}
- */
-function SpecialKey(className, content, keyId) {
-  this.modeElements_ = {};
-  this.cellType_ = 'nc';
-  this.content_ = content;
-  this.keyId_ = keyId;
-  this.className_ = className;
-}
-
-SpecialKey.prototype = {
-  __proto__: BaseKey.prototype,
-
-  /** @override */
-  makeDOM: function(mode) {
-    this.modeElements_[mode] = document.createElement('div');
-    this.modeElements_[mode].className = 'key dark';
-    this.modeElements_[mode].classList.add(this.className_);
-    addContent(this.modeElements_[mode], this.content_);
-
-    setupKeyEventHandlers(this, this.modeElements_[mode],
-        { 'up': sendKeyFunction(this.keyId_) });
-
-    return this.modeElements_[mode];
-  }
-};
-
-/**
- * A shift key.
- * @constructor
- * @param {string} className The class name for the key.
- * @extends {BaseKey}
- */
-function ShiftKey(className) {
-  this.modeElements_ = {};
-  this.cellType_ = 'nc';
-  this.className_ = className;
-}
-
-ShiftKey.prototype = {
-  __proto__: BaseKey.prototype,
-
-  /** @override */
-  makeDOM: function(mode) {
-    this.modeElements_[mode] = document.createElement('div');
-    this.modeElements_[mode].className = 'key shift dark';
-    this.modeElements_[mode].classList.add(this.className_);
-
-    if (mode == KEY_MODE || mode == SHIFT_MODE) {
-      addContent(this.modeElements_[mode]);
-    } else if (mode == NUMBER_MODE) {
-      addContent(this.modeElements_[mode], 'more');
-    } else if (mode == SYMBOL_MODE) {
-      addContent(this.modeElements_[mode], '#123');
-    }
-
-    if (mode == SHIFT_MODE || mode == SYMBOL_MODE) {
-      this.modeElements_[mode].classList.add('moddown');
-    } else {
-      this.modeElements_[mode].classList.remove('moddown');
-    }
-
-    setupKeyEventHandlers(this, this.modeElements_[mode],
-        { 'down': function() {
-          transitionMode(SHIFT_MODE);
-        }});
-
-    return this.modeElements_[mode];
-  },
-};
-
-/**
- * The symbol key: switches the keyboard into symbol mode.
- * @constructor
- * @extends {BaseKey}
- */
-function SymbolKey() {
-  this.modeElements_ = {};
-  this.cellType_ = 'nc';
-}
-
-SymbolKey.prototype = {
-  __proto__: BaseKey.prototype,
-
-  /** @override */
-  makeDOM: function(mode, height) {
-    this.modeElements_[mode] = document.createElement('div');
-    this.modeElements_[mode].className = 'key symbol dark';
-
-    if (mode == KEY_MODE || mode == SHIFT_MODE) {
-      addContent(this.modeElements_[mode], '#123');
-    } else if (mode == NUMBER_MODE || mode == SYMBOL_MODE) {
-      addContent(this.modeElements_[mode], 'abc');
-    }
-
-    if (mode == NUMBER_MODE || mode == SYMBOL_MODE) {
-      this.modeElements_[mode].classList.add('moddown');
-    } else {
-      this.modeElements_[mode].classList.remove('moddown');
-    }
-
-    setupKeyEventHandlers(this, this.modeElements_[mode],
-        { 'down': function() {
-          transitionMode(NUMBER_MODE);
-        }});
-
-    return this.modeElements_[mode];
-  }
-};
-
-/**
- * The ".com" key.
- * @constructor
- * @extends {BaseKey}
- */
-function DotComKey() {
-  this.modeElements_ = {};
-  this.cellType_ = 'nc';
-}
-
-DotComKey.prototype = {
-  __proto__: BaseKey.prototype,
-
-  /** @override */
-  makeDOM: function(mode) {
-    this.modeElements_[mode] = document.createElement('div');
-    this.modeElements_[mode].className = 'key com dark';
-    addContent(this.modeElements_[mode], '.com');
-
-    setupKeyEventHandlers(this, this.modeElements_[mode],
-        { 'up': function() {
-          sendKeyRaw('.');
-          sendKeyRaw('c');
-          sendKeyRaw('o');
-          sendKeyRaw('m');
-        }});
-
-    return this.modeElements_[mode];
-  }
-};
-
-/**
- * The key that hides the keyboard.
- * @constructor
- * @extends {BaseKey}
- */
-function HideKeyboardKey() {
-  this.modeElements_ = {};
-  this.cellType_ = 'nc';
-}
-
-HideKeyboardKey.prototype = {
-  __proto__: BaseKey.prototype,
-
-  /** @override */
-  makeDOM: function(mode) {
-    this.modeElements_[mode] = document.createElement('div');
-    this.modeElements_[mode].className = 'key hide dark';
-    addContent(this.modeElements_[mode]);
-
-    setupKeyEventHandlers(this, this.modeElements_[mode],
-        { 'down': function() { console.log('Hide the keyboard!'); } });
-
-    return this.modeElements_[mode];
-  }
-};
-
-/**
- * The mic key: activate speech input.
- * @constructor
- * @extends {BaseKey}
- */
-function MicKey() {
-  this.modeElements_ = {};
-  this.recognition_ = new webkitSpeechRecognition();
-  this.recognition_.onstart = this.onStartHandler.bind(this);
-  this.recognition_.onresult = this.onResultHandler.bind(this);
-  this.recognition_.onerror = this.onErrorHandler.bind(this);
-  this.recognition_.onend = this.onEndHandler.bind(this);
-  this.finalResult_ = '';
-  this.recognizing_ = false;
-  this.cellType_ = 'nc';
-}
-
-MicKey.prototype = {
-  __proto__: BaseKey.prototype,
-
-  /**
-   * Event handler for mouse/touch down events.
-   */
-  onDown: function() {
-    if (this.recognizing_) {
-      this.recognition_.stop();
-      return;
-    }
-    this.recognition_.start();
-  },
-
-  /**
-   * Speech recognition started. Change mic key's icon.
-   */
-  onStartHandler: function() {
-    this.recognizing_ = true;
-    this.finalResult_ = '';
-    for (var i = 0; i < MODES.length; ++i)
-      this.modeElements_[MODES[i]].classList.add('start');
-  },
-
-  /**
-   * Speech recognizer returns a result.
-   * @param{Event} e The SpeechRecognition event that is raised each time there
-   *     are any changes to interim or final results.
-   */
-  onResultHandler: function(e) {
-    for (var i = e.resultIndex; i < e.results.length; i++) {
-      if (e.results[i].isFinal)
-        this.finalResult_ = e.results[i][0].transcript;
-    }
-    for (var i = 0; i < this.finalResult_.length; i++) {
-      sendKeyRaw(this.finalResult_.charAt(i));
-    }
-  },
-
-  /**
-   * Speech recognizer returns an error.
-   * @param{Event} e The SpeechRecognitionError event that is raised each time
-   *     there is an error.
-   */
-  onErrorHandler: function(e) {
-    console.error('error code = ' + e.error);
-  },
-
-  /**
-   * Speech recognition ended. Reset mic key's icon.
-   */
-  onEndHandler: function() {
-   for (var i = 0; i < MODES.length; ++i)
-     this.modeElements_[MODES[i]].classList.remove('start');
-
-   this.recognizing_ = false;
-  },
-
-  /** @override */
-  makeDOM: function(mode) {
-    this.modeElements_[mode] = document.createElement('div');
-    this.modeElements_[mode].className = 'key mic';
-    addContent(this.modeElements_[mode]);
-
-    setupKeyEventHandlers(this, this.modeElements_[mode],
-        { 'down': this.onDown.bind(this) });
-
-    return this.modeElements_[mode];
-  }
-};
-
-/**
- * A container for keys.
- * @param {number} position The position of the row (0-3).
- * @param {Array.<BaseKey>} keys The keys in the row.
- * @constructor
- */
-function Row(position, keys) {
-  this.position_ = position;
-  this.keys_ = keys;
-  this.element_ = null;
-  this.modeElements_ = {};
-}
-
-Row.prototype = {
-  /**
-   * Create the DOM elements for the row.
-   * @return {Element} The top-level DOM Element for the row.
-   */
-  makeDOM: function() {
-    this.element_ = document.createElement('div');
-    this.element_.className = 'row';
-    for (var i = 0; i < MODES.length; ++i) {
-      var mode = MODES[i];
-      this.modeElements_[mode] = document.createElement('div');
-      this.modeElements_[mode].style.display = 'none';
-      this.element_.appendChild(this.modeElements_[mode]);
-    }
-
-    for (var j = 0; j < this.keys_.length; ++j) {
-      var key = this.keys_[j];
-      for (var i = 0; i < MODES.length; ++i) {
-        var keyDom = key.makeDOM(MODES[i]);
-        if (keyDom) {
-          this.modeElements_[MODES[i]].appendChild(keyDom);
-        }
-      }
-    }
-
-    for (var i = 0; i < MODES.length; ++i) {
-      var clearingDiv = document.createElement('div');
-      clearingDiv.style.clear = 'both';
-      this.modeElements_[MODES[i]].appendChild(clearingDiv);
-    }
-
-    return this.element_;
-  },
-
-  /**
-   * Shows the given mode.
-   * @param {string} mode The mode to show.
-   */
-  showMode: function(mode) {
-    for (var i = 0; i < MODES.length; ++i) {
-      this.modeElements_[MODES[i]].style.display = 'none';
-    }
-    this.modeElements_[mode].style.display = '-webkit-box';
-  },
-
-  /**
-   * Returns the size of keys this row contains.
-   * @return {number} The size of keys.
-   */
-  get length() {
-    return this.keys_.length;
-  }
-};