chrome/browser/resources/chromeos/chromevox/common/focuser.js

   1 // Copyright 2014 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  * @fileoverview Implements the setFocus function.
   7  */
   8
   9 goog.provide('cvox.Focuser');
  10
  11 goog.require('cvox.ChromeVoxEventSuspender');
  12 goog.require('cvox.DomUtil');
  13
  14
  15 /**
  16  * Sets the browser focus to the targetNode or its closest ancestor that is
  17  * focusable.
  18  *
  19  * @param {Node} targetNode The node to move the browser focus to.
  20  * @param {boolean=} opt_focusDescendants Whether or not we check descendants
  21  * of the target node to see if they are focusable. If true, sets focus on the
  22  * first focusable descendant. If false, only sets focus on the targetNode or
  23  * its closest ancestor. Default is false.
  24  */
  25 cvox.Focuser.setFocus = function(targetNode, opt_focusDescendants) {
  26   // Save the selection because Chrome will lose it if there's a focus or blur.
  27   var sel = window.getSelection();
  28   var range;
  29   if (sel.rangeCount > 0) {
  30     range = sel.getRangeAt(0);
  31   }
  32   // Blur the currently-focused element if the target node is not a descendant.
  33   if (document.activeElement &&
  34       !cvox.DomUtil.isDescendantOfNode(targetNode, document.activeElement)) {
  35     document.activeElement.blur();
  36   }
  37
  38   // Video elements should always be focusable.
  39   if (targetNode && (targetNode.constructor == HTMLVideoElement)) {
  40     if (!cvox.DomUtil.isFocusable(targetNode)) {
  41       targetNode.setAttribute('tabIndex', 0);
  42     }
  43   }
  44
  45   if (opt_focusDescendants && !cvox.DomUtil.isFocusable(targetNode)) {
  46     var focusableDescendant = cvox.DomUtil.findFocusableDescendant(targetNode);
  47     if (focusableDescendant) {
  48       targetNode = focusableDescendant;
  49     }
  50   } else {
  51     // Search up the parent chain until a focusable node is found.
  52     while (targetNode && !cvox.DomUtil.isFocusable(targetNode)) {
  53       targetNode = targetNode.parentNode;
  54     }
  55   }
  56
  57   // If we found something focusable, focus it - otherwise, blur it.
  58   if (cvox.DomUtil.isFocusable(targetNode)) {
  59     // Don't let the instance of ChromeVox in the parent focus iframe children
  60     // - instead, let the instance of ChromeVox in the iframe focus itself to
  61     // avoid getting trapped in iframes that have no ChromeVox in them.
  62     // This self focusing is performed by calling window.focus() in
  63     // cvox.NavigationManager.prototype.addInterframeListener_
  64     if (targetNode.tagName != 'IFRAME') {
  65       // setTimeout must be used because there's a bug (in Chrome, I think)
  66       // with .focus() which causes the page to be redrawn incorrectly if
  67       // not in setTimeout.
  68       if (cvox.ChromeVoxEventSuspender.areEventsSuspended()) {
  69         if (cvox.Focuser.shouldEnterSuspendEvents_(targetNode)) {
  70           cvox.ChromeVoxEventSuspender.enterSuspendEvents();
  71         }
  72         window.setTimeout(function() {
  73           targetNode.focus();
  74           cvox.ChromeVoxEventSuspender.exitSuspendEvents();
  75         }, 0);
  76       }
  77       else {
  78         window.setTimeout(function() {
  79             targetNode.focus();
  80         }, 0);
  81       }
  82     }
  83   } else if (document.activeElement &&
  84              document.activeElement.tagName != 'BODY') {
  85     document.activeElement.blur();
  86   }
  87
  88   // Restore the selection, unless the focused item is a text box.
  89   if (cvox.DomUtil.isInputTypeText(targetNode)) {
  90     targetNode.select();
  91   } else if (range) {
  92     sel.removeAllRanges();
  93     sel.addRange(range);
  94   }
  95 };
  96
  97 /**
  98  * Rules for whether or not enterSuspendEvents should be called.
  99  * In general, we should not enterSuspendEvents if the targetNode will get some
 100  * special handlers attached when a focus event is received for it; otherwise,
 101  * the special handlers will not get attached.
 102  *
 103  * @param {Node} targetNode The node that is being focused.
 104  * @return {boolean} True if enterSuspendEvents should be called.
 105  */
 106 cvox.Focuser.shouldEnterSuspendEvents_ = function(targetNode){
 107   if (targetNode.constructor && targetNode.constructor == HTMLVideoElement) {
 108     return false;
 109   }
 110   if (targetNode.hasAttribute) {
 111     switch (targetNode.getAttribute('type')) {
 112       case 'time':
 113       case 'date':
 114       case 'week':
 115       case 'month':
 116         return false;
 117     }
 118   }
 119   return true;
 120 };