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 left and right keypress and keyup events.
  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' || event.keyIdentifier == 'Right') {
  20     event.stopPropagation();
  21     event.preventDefault();
  22   }
  23 };
  24
  25 /**
  26  * Converts right/left into tab/shift-tab key events.
  27  * @param {KeyboardEvent} event Raised event.
  28  * @private
  29  */
  30 keyboard.onKeyDown_ = function(event) {
  31    if (event.ctrlKey || event.shiftKey || event.altKey || event.metaKey)
  32      return;
  33
  34    if (event.keyIdentifier == 'Left') {
  35      keyboard.raiseKeyFocusPrevious(document.activeElement);
  36      event.stopPropagation();
  37      event.preventDefault();
  38    } else if (event.keyIdentifier == 'Right') {
  39      keyboard.raiseKeyFocusNext(document.activeElement);
  40      event.stopPropagation();
  41      event.preventDefault();
  42    }
  43 };
  44
  45 /**
  46  * Raises tab/shift-tab keyboard events.
  47  * @param {HTMLElement} element Element that should receive the event.
  48  * @param {string} eventType Keyboard event type.
  49  * @param {boolean} shift True if shift should be on.
  50  * @private
  51  */
  52 keyboard.raiseTabKeyEvent_ = function(element, eventType, shift) {
  53   var event = document.createEvent('KeyboardEvent');
  54   event.initKeyboardEvent(
  55       eventType,
  56       true,  // canBubble
  57       true,  // cancelable
  58       window,
  59       'U+0009',
  60       0,  // keyLocation
  61       false,  // ctrl
  62       false,  // alt
  63       shift,  // shift
  64       false);  // meta
  65   element.dispatchEvent(event);
  66 };
  67
  68 /**
  69  * Raises shift+tab keyboard events to focus previous element.
  70  * @param {HTMLElement} element Element that should receive the event.
  71  */
  72 keyboard.raiseKeyFocusPrevious = function(element) {
  73   keyboard.raiseTabKeyEvent_(element, 'keydown', true);
  74   keyboard.raiseTabKeyEvent_(element, 'keypress', true);
  75   keyboard.raiseTabKeyEvent_(element, 'keyup', true);
  76 };
  77
  78 /**
  79  * Raises tab keyboard events to focus next element.
  80  * @param {HTMLElement} element Element that should receive the event.
  81  */
  82 keyboard.raiseKeyFocusNext = function(element) {
  83   keyboard.raiseTabKeyEvent_(element, 'keydown', false);
  84   keyboard.raiseTabKeyEvent_(element, 'keypress', false);
  85   keyboard.raiseTabKeyEvent_(element, 'keyup', false);
  86 };
  87
  88 /**
  89  * Initializes event handling for arrow keys driven focus flow.
  90  */
  91 keyboard.initializeKeyboardFlow = function() {
  92   document.addEventListener('keydown',
  93       keyboard.onKeyDown_, true);
  94   document.addEventListener('keypress',
  95       keyboard.onKeyIgnore_, true);
  96   document.addEventListener('keyup',
  97       keyboard.onKeyIgnore_, true);
  98 };