chrome/browser/resources/chromeos/keyboard/keyboard_utils.js

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * Namespace for keyboard utility functions.
   7  */
   8 var keyboard = {};
   9
  10 /**
  11  * Swallows keypress and keyup events of arrow keys.
  12  * @param {KeyboardEvent} event Raised event.
  13  * @private
  14  */
  15 keyboard.onKeyIgnore_ = function(event) {
  16   if (event.ctrlKey || event.shiftKey || event.altKey || event.metaKey)
  17     return;
  18
  19   if (event.keyIdentifier == 'Left' ||
  20       event.keyIdentifier == 'Right' ||
  21       event.keyIdentifier == 'Up' ||
  22       event.keyIdentifier == 'Down') {
  23     event.stopPropagation();
  24     event.preventDefault();
  25   }
  26 };
  27
  28 /**
  29  * Converts arrow keys into tab/shift-tab key events.
  30  * @param {KeyboardEvent} event Raised event.
  31  * @private
  32  */
  33 keyboard.onKeyDown_ = function(event) {
  34    if (event.ctrlKey || event.shiftKey || event.altKey || event.metaKey)
  35      return;
  36
  37    var needsUpDownKeys = event.target.classList.contains('needs-up-down-keys');
  38
  39    if (event.keyIdentifier == 'Left' ||
  40        (!needsUpDownKeys && event.keyIdentifier == 'Up')) {
  41      keyboard.raiseKeyFocusPrevious(document.activeElement);
  42      event.stopPropagation();
  43      event.preventDefault();
  44    } else if (event.keyIdentifier == 'Right' ||
  45               (!needsUpDownKeys && event.keyIdentifier == 'Down')) {
  46      keyboard.raiseKeyFocusNext(document.activeElement);
  47      event.stopPropagation();
  48      event.preventDefault();
  49    }
  50 };
  51
  52 /**
  53  * Raises tab/shift-tab keyboard events.
  54  * @param {HTMLElement} element Element that should receive the event.
  55  * @param {string} eventType Keyboard event type.
  56  * @param {boolean} shift True if shift should be on.
  57  * @private
  58  */
  59 keyboard.raiseTabKeyEvent_ = function(element, eventType, shift) {
  60   var event = document.createEvent('KeyboardEvent');
  61   event.initKeyboardEvent(
  62       eventType,
  63       true,  // canBubble
  64       true,  // cancelable
  65       window,
  66       'U+0009',
  67       0,  // keyLocation
  68       false,  // ctrl
  69       false,  // alt
  70       shift,  // shift
  71       false);  // meta
  72   element.dispatchEvent(event);
  73 };
  74
  75 /**
  76  * Raises shift+tab keyboard events to focus previous element.
  77  * @param {HTMLElement} element Element that should receive the event.
  78  */
  79 keyboard.raiseKeyFocusPrevious = function(element) {
  80   keyboard.raiseTabKeyEvent_(element, 'keydown', true);
  81   keyboard.raiseTabKeyEvent_(element, 'keypress', true);
  82   keyboard.raiseTabKeyEvent_(element, 'keyup', true);
  83 };
  84
  85 /**
  86  * Raises tab keyboard events to focus next element.
  87  * @param {HTMLElement} element Element that should receive the event.
  88  */
  89 keyboard.raiseKeyFocusNext = function(element) {
  90   keyboard.raiseTabKeyEvent_(element, 'keydown', false);
  91   keyboard.raiseTabKeyEvent_(element, 'keypress', false);
  92   keyboard.raiseTabKeyEvent_(element, 'keyup', false);
  93 };
  94
  95 /**
  96  * Initializes event handling for arrow keys driven focus flow.
  97  */
  98 keyboard.initializeKeyboardFlow = function() {
  99   document.addEventListener('keydown',
 100       keyboard.onKeyDown_, true);
 101   document.addEventListener('keypress',
 102       keyboard.onKeyIgnore_, true);
 103   document.addEventListener('keyup',
 104       keyboard.onKeyIgnore_, true);
 105 };