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 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

  * You can obtain one at http://mozilla.org/MPL/2.0/. */

 'use strict';

 const Cc = Components.classes;

 const Ci = Components.interfaces;

 const Cu = Components.utils;

 const Cr = Components.results;

 this.EXPORTED_SYMBOLS = ['TraversalRules'];

 Cu.import('resource://gre/modules/accessibility/Utils.jsm');

 Cu.import('resource://gre/modules/XPCOMUtils.jsm');

 XPCOMUtils.defineLazyModuleGetter(this, 'Roles',

   'resource://gre/modules/accessibility/Constants.jsm');

 XPCOMUtils.defineLazyModuleGetter(this, 'Filters',

   'resource://gre/modules/accessibility/Constants.jsm');

 XPCOMUtils.defineLazyModuleGetter(this, 'States',

   'resource://gre/modules/accessibility/Constants.jsm');

 XPCOMUtils.defineLazyModuleGetter(this, 'Prefilters',

   'resource://gre/modules/accessibility/Constants.jsm');

 let gSkipEmptyImages = new PrefCache('accessibility.accessfu.skip_empty_images');

 function BaseTraversalRule(aRoles, aMatchFunc, aPreFilter) {

   this._explicitMatchRoles = new Set(aRoles);

   this._matchRoles = aRoles;

   if (aRoles.indexOf(Roles.LABEL) < 0) {

     this._matchRoles.push(Roles.LABEL);

   }

   this._matchFunc = aMatchFunc || function (acc) { return Filters.MATCH; };

   this.preFilter = aPreFilter || gSimplePreFilter;

 }

 BaseTraversalRule.prototype = {

     getMatchRoles: function BaseTraversalRule_getmatchRoles(aRules) {

       aRules.value = this._matchRoles;

       return aRules.value.length;

     },

     match: function BaseTraversalRule_match(aAccessible)

     {

       let role = aAccessible.role;

       if (role == Roles.INTERNAL_FRAME) {

         return (Utils.getMessageManager(aAccessible.DOMNode)) ?

           Filters.MATCH  | Filters.IGNORE_SUBTREE : Filters.IGNORE;

       }

       let matchResult = this._explicitMatchRoles.has(role) ?

           this._matchFunc(aAccessible) : Filters.IGNORE;

       // If we are on a label that nests a checkbox/radio we should land on it.

       // It is a bigger touch target, and it reduces clutter.

       if (role == Roles.LABEL && !(matchResult & Filters.IGNORE_SUBTREE)) {

         let control = Utils.getEmbeddedControl(aAccessible);

         if (control && this._explicitMatchRoles.has(control.role)) {

           matchResult = this._matchFunc(control) | Filters.IGNORE_SUBTREE;

         }

       }

       return matchResult;

     },

     QueryInterface: XPCOMUtils.generateQI([Ci.nsIAccessibleTraversalRule])

 };

 var gSimpleTraversalRoles =

   [Roles.MENUITEM,

    Roles.LINK,

    Roles.PAGETAB,

    Roles.GRAPHIC,

    Roles.STATICTEXT,

    Roles.TEXT_LEAF,

    Roles.PUSHBUTTON,

    Roles.CHECKBUTTON,

    Roles.RADIOBUTTON,

    Roles.COMBOBOX,

    Roles.PROGRESSBAR,

    Roles.BUTTONDROPDOWN,

    Roles.BUTTONMENU,

    Roles.CHECK_MENU_ITEM,

    Roles.PASSWORD_TEXT,

    Roles.RADIO_MENU_ITEM,

    Roles.TOGGLE_BUTTON,

    Roles.ENTRY,

    Roles.KEY,

    Roles.HEADER,

    Roles.HEADING,

    Roles.SLIDER,

    Roles.SPINBUTTON,

    Roles.OPTION,

    // Used for traversing in to child OOP frames.

    Roles.INTERNAL_FRAME];

 var gSimpleMatchFunc = function gSimpleMatchFunc(aAccessible) {

   function hasZeroOrSingleChildDescendants () {

     for (let acc = aAccessible; acc.childCount > 0; acc = acc.firstChild) {

       if (acc.childCount > 1) {

         return false;

       }

     }

     return true;

   }

   switch (aAccessible.role) {

   case Roles.COMBOBOX:

     // We don't want to ignore the subtree because this is often

     // where the list box hangs out.

     return Filters.MATCH;

   case Roles.TEXT_LEAF:

     {

       // Nameless text leaves are boring, skip them.

       let name = aAccessible.name;

       if (name && name.trim())

         return Filters.MATCH;

       else

         return Filters.IGNORE;

     }

   case Roles.STATICTEXT:

     {

       let parent = aAccessible.parent;

       // Ignore prefix static text in list items. They are typically bullets or numbers.

       if (parent.childCount > 1 && aAccessible.indexInParent == 0 &&

           parent.role == Roles.LISTITEM)

         return Filters.IGNORE;

       return Filters.MATCH;

     }

   case Roles.GRAPHIC:

     return TraversalRules._shouldSkipImage(aAccessible);

   case Roles.HEADER:

   case Roles.HEADING:

     if ((aAccessible.childCount > 0 || aAccessible.name) &&

         hasZeroOrSingleChildDescendants()) {

       return Filters.MATCH | Filters.IGNORE_SUBTREE;

     } else {

       return Filters.IGNORE;

     }

   default:

     // Ignore the subtree, if there is one. So that we don't land on

     // the same content that was already presented by its parent.

     return Filters.MATCH |

       Filters.IGNORE_SUBTREE;

   }

 };

 var gSimplePreFilter = Prefilters.DEFUNCT |

   Prefilters.INVISIBLE |

   Prefilters.ARIA_HIDDEN |

   Prefilters.TRANSPARENT;

 this.TraversalRules = {

   Simple: new BaseTraversalRule(gSimpleTraversalRoles, gSimpleMatchFunc),

   SimpleOnScreen: new BaseTraversalRule(

     gSimpleTraversalRoles, gSimpleMatchFunc,

     Prefilters.DEFUNCT | Prefilters.INVISIBLE | Prefilters.ARIA_HIDDEN |

     Prefilters.TRANSPARENT | Prefilters.OFFSCREEN),

   Anchor: new BaseTraversalRule(

     [Roles.LINK],

     function Anchor_match(aAccessible)

     {

       // We want to ignore links, only focus named anchors.

       if (Utils.getState(aAccessible).contains(States.LINKED)) {

         return Filters.IGNORE;

       } else {

         return Filters.MATCH;

       }

     }),

   Button: new BaseTraversalRule(

     [Roles.PUSHBUTTON,

      Roles.SPINBUTTON,

      Roles.TOGGLE_BUTTON,

      Roles.BUTTONDROPDOWN,

      Roles.BUTTONDROPDOWNGRID]),

   Combobox: new BaseTraversalRule(

     [Roles.COMBOBOX,

      Roles.LISTBOX]),

   Landmark: new BaseTraversalRule(

     [],

     function Landmark_match(aAccessible) {

       return Utils.getLandmarkName(aAccessible) ? Filters.MATCH :

         Filters.IGNORE;

     }

   ),

   Entry: new BaseTraversalRule(

     [Roles.ENTRY,

      Roles.PASSWORD_TEXT]),

   FormElement: new BaseTraversalRule(

     [Roles.PUSHBUTTON,

      Roles.SPINBUTTON,

      Roles.TOGGLE_BUTTON,

      Roles.BUTTONDROPDOWN,

      Roles.BUTTONDROPDOWNGRID,

      Roles.COMBOBOX,

      Roles.LISTBOX,

      Roles.ENTRY,

      Roles.PASSWORD_TEXT,

      Roles.PAGETAB,

      Roles.RADIOBUTTON,

      Roles.RADIO_MENU_ITEM,

      Roles.SLIDER,

      Roles.CHECKBUTTON,

      Roles.CHECK_MENU_ITEM]),

   Graphic: new BaseTraversalRule(

     [Roles.GRAPHIC],

     function Graphic_match(aAccessible) {

       return TraversalRules._shouldSkipImage(aAccessible);

     }),

   Heading: new BaseTraversalRule(

     [Roles.HEADING],

     function Heading_match(aAccessible) {

       return aAccessible.childCount > 0 ? Filters.MATCH : Filters.IGNORE;

     }),

   ListItem: new BaseTraversalRule(

     [Roles.LISTITEM,

      Roles.TERM]),

   Link: new BaseTraversalRule(

     [Roles.LINK],

     function Link_match(aAccessible)

     {

       // We want to ignore anchors, only focus real links.

       if (Utils.getState(aAccessible).contains(States.LINKED)) {

         return Filters.MATCH;

       } else {

         return Filters.IGNORE;

       }

     }),

   List: new BaseTraversalRule(

     [Roles.LIST,

      Roles.DEFINITION_LIST]),

   PageTab: new BaseTraversalRule(

     [Roles.PAGETAB]),

   Paragraph: new BaseTraversalRule(

     [Roles.PARAGRAPH,

      Roles.SECTION],

     function Paragraph_match(aAccessible) {

       for (let child = aAccessible.firstChild; child; child = child.nextSibling) {

         if (child.role === Roles.TEXT_LEAF) {

           return Filters.MATCH | Filters.IGNORE_SUBTREE;

         }

       }

       return Filters.IGNORE;

     }),

   RadioButton: new BaseTraversalRule(

     [Roles.RADIOBUTTON,

      Roles.RADIO_MENU_ITEM]),

   Separator: new BaseTraversalRule(

     [Roles.SEPARATOR]),

   Table: new BaseTraversalRule(

     [Roles.TABLE]),

   Checkbox: new BaseTraversalRule(

     [Roles.CHECKBUTTON,

      Roles.CHECK_MENU_ITEM]),

   _shouldSkipImage: function _shouldSkipImage(aAccessible) {

     if (gSkipEmptyImages.value && aAccessible.name === '') {

       return Filters.IGNORE;

     }

     return Filters.MATCH;

   }

 };