420 lines
12 KiB
JavaScript
420 lines
12 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* global PrefCache, Roles, Prefilters, States, Filters, Utils,
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TraversalRules, Components, XPCOMUtils */
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/* exported TraversalRules, TraversalHelper */
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'use strict';
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const Ci = Components.interfaces;
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const Cu = Components.utils;
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this.EXPORTED_SYMBOLS = ['TraversalRules', 'TraversalHelper']; // jshint ignore:line
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Cu.import('resource://gre/modules/accessibility/Utils.jsm');
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Cu.import('resource://gre/modules/XPCOMUtils.jsm');
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XPCOMUtils.defineLazyModuleGetter(this, 'Roles', // jshint ignore:line
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'resource://gre/modules/accessibility/Constants.jsm');
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XPCOMUtils.defineLazyModuleGetter(this, 'Filters', // jshint ignore:line
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'resource://gre/modules/accessibility/Constants.jsm');
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XPCOMUtils.defineLazyModuleGetter(this, 'States', // jshint ignore:line
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'resource://gre/modules/accessibility/Constants.jsm');
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XPCOMUtils.defineLazyModuleGetter(this, 'Prefilters', // jshint ignore:line
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'resource://gre/modules/accessibility/Constants.jsm');
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var gSkipEmptyImages = new PrefCache('accessibility.accessfu.skip_empty_images');
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function BaseTraversalRule(aRoles, aMatchFunc, aPreFilter, aContainerRule) {
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this._explicitMatchRoles = new Set(aRoles);
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this._matchRoles = aRoles;
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if (aRoles.length) {
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if (aRoles.indexOf(Roles.LABEL) < 0) {
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this._matchRoles.push(Roles.LABEL);
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}
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if (aRoles.indexOf(Roles.INTERNAL_FRAME) < 0) {
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// Used for traversing in to child OOP frames.
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this._matchRoles.push(Roles.INTERNAL_FRAME);
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}
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}
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this._matchFunc = aMatchFunc || function() { return Filters.MATCH; };
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this.preFilter = aPreFilter || gSimplePreFilter;
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this.containerRule = aContainerRule;
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}
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BaseTraversalRule.prototype = {
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getMatchRoles: function BaseTraversalRule_getmatchRoles(aRoles) {
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aRoles.value = this._matchRoles;
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return aRoles.value.length;
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},
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match: function BaseTraversalRule_match(aAccessible)
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{
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let role = aAccessible.role;
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if (role == Roles.INTERNAL_FRAME) {
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return (Utils.getMessageManager(aAccessible.DOMNode)) ?
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Filters.MATCH | Filters.IGNORE_SUBTREE : Filters.IGNORE;
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}
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let matchResult =
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(this._explicitMatchRoles.has(role) || !this._explicitMatchRoles.size) ?
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this._matchFunc(aAccessible) : Filters.IGNORE;
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// If we are on a label that nests a checkbox/radio we should land on it.
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// It is a bigger touch target, and it reduces clutter.
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if (role == Roles.LABEL && !(matchResult & Filters.IGNORE_SUBTREE)) {
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let control = Utils.getEmbeddedControl(aAccessible);
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if (control && this._explicitMatchRoles.has(control.role)) {
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matchResult = this._matchFunc(control) | Filters.IGNORE_SUBTREE;
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}
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}
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return matchResult;
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},
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QueryInterface: XPCOMUtils.generateQI([Ci.nsIAccessibleTraversalRule])
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};
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var gSimpleTraversalRoles =
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[Roles.MENUITEM,
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Roles.LINK,
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Roles.PAGETAB,
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Roles.GRAPHIC,
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Roles.STATICTEXT,
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Roles.TEXT_LEAF,
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Roles.PUSHBUTTON,
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Roles.CHECKBUTTON,
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Roles.RADIOBUTTON,
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Roles.COMBOBOX,
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Roles.PROGRESSBAR,
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Roles.BUTTONDROPDOWN,
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Roles.BUTTONMENU,
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Roles.CHECK_MENU_ITEM,
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Roles.PASSWORD_TEXT,
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Roles.RADIO_MENU_ITEM,
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Roles.TOGGLE_BUTTON,
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Roles.ENTRY,
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Roles.KEY,
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Roles.HEADER,
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Roles.HEADING,
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Roles.SLIDER,
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Roles.SPINBUTTON,
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Roles.OPTION,
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Roles.LISTITEM,
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Roles.GRID_CELL,
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Roles.COLUMNHEADER,
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Roles.ROWHEADER,
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Roles.STATUSBAR,
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Roles.SWITCH,
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Roles.MATHML_MATH];
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var gSimpleMatchFunc = function gSimpleMatchFunc(aAccessible) {
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// An object is simple, if it either has a single child lineage,
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// or has a flat subtree.
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function isSingleLineage(acc) {
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for (let child = acc; child; child = child.firstChild) {
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if (Utils.visibleChildCount(child) > 1) {
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return false;
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}
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}
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return true;
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}
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function isFlatSubtree(acc) {
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for (let child = acc.firstChild; child; child = child.nextSibling) {
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// text leafs inherit the actionCount of any ancestor that has a click
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// listener.
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if ([Roles.TEXT_LEAF, Roles.STATICTEXT].indexOf(child.role) >= 0) {
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continue;
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}
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if (Utils.visibleChildCount(child) > 0 || child.actionCount > 0) {
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return false;
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}
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}
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return true;
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}
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switch (aAccessible.role) {
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case Roles.COMBOBOX:
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// We don't want to ignore the subtree because this is often
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// where the list box hangs out.
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return Filters.MATCH;
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case Roles.TEXT_LEAF:
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{
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// Nameless text leaves are boring, skip them.
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let name = aAccessible.name;
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return (name && name.trim()) ? Filters.MATCH : Filters.IGNORE;
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}
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case Roles.STATICTEXT:
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// Ignore prefix static text in list items. They are typically bullets or numbers.
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return Utils.isListItemDecorator(aAccessible) ?
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Filters.IGNORE : Filters.MATCH;
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case Roles.GRAPHIC:
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return TraversalRules._shouldSkipImage(aAccessible);
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case Roles.HEADER:
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case Roles.HEADING:
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case Roles.COLUMNHEADER:
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case Roles.ROWHEADER:
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case Roles.STATUSBAR:
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if ((aAccessible.childCount > 0 || aAccessible.name) &&
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(isSingleLineage(aAccessible) || isFlatSubtree(aAccessible))) {
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return Filters.MATCH | Filters.IGNORE_SUBTREE;
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}
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return Filters.IGNORE;
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case Roles.GRID_CELL:
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return isSingleLineage(aAccessible) || isFlatSubtree(aAccessible) ?
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Filters.MATCH | Filters.IGNORE_SUBTREE : Filters.IGNORE;
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case Roles.LISTITEM:
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{
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let item = aAccessible.childCount === 2 &&
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aAccessible.firstChild.role === Roles.STATICTEXT ?
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aAccessible.lastChild : aAccessible;
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return isSingleLineage(item) || isFlatSubtree(item) ?
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Filters.MATCH | Filters.IGNORE_SUBTREE : Filters.IGNORE;
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}
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default:
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// Ignore the subtree, if there is one. So that we don't land on
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// the same content that was already presented by its parent.
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return Filters.MATCH |
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Filters.IGNORE_SUBTREE;
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}
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};
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var gSimplePreFilter = Prefilters.DEFUNCT |
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Prefilters.INVISIBLE |
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Prefilters.ARIA_HIDDEN |
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Prefilters.TRANSPARENT;
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this.TraversalRules = { // jshint ignore:line
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Simple: new BaseTraversalRule(gSimpleTraversalRoles, gSimpleMatchFunc),
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SimpleOnScreen: new BaseTraversalRule(
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gSimpleTraversalRoles, gSimpleMatchFunc,
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Prefilters.DEFUNCT | Prefilters.INVISIBLE | Prefilters.ARIA_HIDDEN |
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Prefilters.TRANSPARENT | Prefilters.OFFSCREEN),
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Anchor: new BaseTraversalRule(
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[Roles.LINK],
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function Anchor_match(aAccessible)
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{
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// We want to ignore links, only focus named anchors.
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if (Utils.getState(aAccessible).contains(States.LINKED)) {
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return Filters.IGNORE;
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} else {
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return Filters.MATCH;
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}
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}),
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Button: new BaseTraversalRule(
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[Roles.PUSHBUTTON,
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Roles.SPINBUTTON,
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Roles.TOGGLE_BUTTON,
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Roles.BUTTONDROPDOWN,
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Roles.BUTTONDROPDOWNGRID]),
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Combobox: new BaseTraversalRule(
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[Roles.COMBOBOX,
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Roles.LISTBOX]),
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Landmark: new BaseTraversalRule(
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[],
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function Landmark_match(aAccessible) {
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return Utils.getLandmarkName(aAccessible) ? Filters.MATCH :
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Filters.IGNORE;
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}, null, true),
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/* A rule for Android's section navigation, lands on landmarks, regions, and
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on headings to aid navigation of traditionally structured documents */
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Section: new BaseTraversalRule(
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[],
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function Section_match(aAccessible) {
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if (aAccessible.role === Roles.HEADING) {
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return Filters.MATCH;
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}
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let matchedRole = Utils.matchRoles(aAccessible, [
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'banner',
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'complementary',
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'contentinfo',
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'main',
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'navigation',
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'search',
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'region'
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]);
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return matchedRole ? Filters.MATCH : Filters.IGNORE;
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}, null, true),
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Entry: new BaseTraversalRule(
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[Roles.ENTRY,
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Roles.PASSWORD_TEXT]),
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FormElement: new BaseTraversalRule(
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[Roles.PUSHBUTTON,
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Roles.SPINBUTTON,
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Roles.TOGGLE_BUTTON,
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Roles.BUTTONDROPDOWN,
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Roles.BUTTONDROPDOWNGRID,
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Roles.COMBOBOX,
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Roles.LISTBOX,
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Roles.ENTRY,
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Roles.PASSWORD_TEXT,
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Roles.PAGETAB,
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Roles.RADIOBUTTON,
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Roles.RADIO_MENU_ITEM,
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Roles.SLIDER,
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Roles.CHECKBUTTON,
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Roles.CHECK_MENU_ITEM,
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Roles.SWITCH]),
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Graphic: new BaseTraversalRule(
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[Roles.GRAPHIC],
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function Graphic_match(aAccessible) {
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return TraversalRules._shouldSkipImage(aAccessible);
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}),
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Heading: new BaseTraversalRule(
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[Roles.HEADING],
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function Heading_match(aAccessible) {
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return aAccessible.childCount > 0 ? Filters.MATCH : Filters.IGNORE;
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}),
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ListItem: new BaseTraversalRule(
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[Roles.LISTITEM,
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Roles.TERM]),
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Link: new BaseTraversalRule(
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[Roles.LINK],
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function Link_match(aAccessible)
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{
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// We want to ignore anchors, only focus real links.
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if (Utils.getState(aAccessible).contains(States.LINKED)) {
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return Filters.MATCH;
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} else {
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return Filters.IGNORE;
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}
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}),
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/* For TalkBack's "Control" granularity. Form conrols and links */
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Control: new BaseTraversalRule(
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[Roles.PUSHBUTTON,
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Roles.SPINBUTTON,
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Roles.TOGGLE_BUTTON,
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Roles.BUTTONDROPDOWN,
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Roles.BUTTONDROPDOWNGRID,
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Roles.COMBOBOX,
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Roles.LISTBOX,
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Roles.ENTRY,
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Roles.PASSWORD_TEXT,
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Roles.PAGETAB,
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Roles.RADIOBUTTON,
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Roles.RADIO_MENU_ITEM,
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Roles.SLIDER,
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Roles.CHECKBUTTON,
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Roles.CHECK_MENU_ITEM,
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Roles.SWITCH,
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Roles.LINK,
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Roles.MENUITEM],
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function Control_match(aAccessible)
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{
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// We want to ignore anchors, only focus real links.
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if (aAccessible.role == Roles.LINK &&
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!Utils.getState(aAccessible).contains(States.LINKED)) {
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return Filters.IGNORE;
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}
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return Filters.MATCH;
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}),
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List: new BaseTraversalRule(
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[Roles.LIST,
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Roles.DEFINITION_LIST],
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null, null, true),
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PageTab: new BaseTraversalRule(
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[Roles.PAGETAB]),
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Paragraph: new BaseTraversalRule(
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[Roles.PARAGRAPH,
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Roles.SECTION],
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function Paragraph_match(aAccessible) {
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for (let child = aAccessible.firstChild; child; child = child.nextSibling) {
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if (child.role === Roles.TEXT_LEAF) {
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return Filters.MATCH | Filters.IGNORE_SUBTREE;
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}
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}
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return Filters.IGNORE;
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}),
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RadioButton: new BaseTraversalRule(
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[Roles.RADIOBUTTON,
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Roles.RADIO_MENU_ITEM]),
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Separator: new BaseTraversalRule(
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[Roles.SEPARATOR]),
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Table: new BaseTraversalRule(
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[Roles.TABLE]),
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Checkbox: new BaseTraversalRule(
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[Roles.CHECKBUTTON,
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Roles.CHECK_MENU_ITEM,
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Roles.SWITCH /* A type of checkbox that represents on/off values */]),
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_shouldSkipImage: function _shouldSkipImage(aAccessible) {
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if (gSkipEmptyImages.value && aAccessible.name === '') {
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return Filters.IGNORE;
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}
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return Filters.MATCH;
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}
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};
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this.TraversalHelper = {
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_helperPivotCache: null,
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get helperPivotCache() {
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delete this.helperPivotCache;
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this.helperPivotCache = new WeakMap();
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return this.helperPivotCache;
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},
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getHelperPivot: function TraversalHelper_getHelperPivot(aRoot) {
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let pivot = this.helperPivotCache.get(aRoot.DOMNode);
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if (!pivot) {
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pivot = Utils.AccRetrieval.createAccessiblePivot(aRoot);
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this.helperPivotCache.set(aRoot.DOMNode, pivot);
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}
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return pivot;
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},
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move: function TraversalHelper_move(aVirtualCursor, aMethod, aRule) {
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let rule = TraversalRules[aRule];
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if (rule.containerRule) {
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let moved = false;
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let helperPivot = this.getHelperPivot(aVirtualCursor.root);
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helperPivot.position = aVirtualCursor.position;
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// We continue to step through containers until there is one with an
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// atomic child (via 'Simple') on which we could land.
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while (!moved) {
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if (helperPivot[aMethod](rule)) {
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aVirtualCursor.modalRoot = helperPivot.position;
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moved = aVirtualCursor.moveFirst(TraversalRules.Simple);
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aVirtualCursor.modalRoot = null;
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} else {
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// If we failed to step to another container, break and return false.
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break;
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}
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}
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return moved;
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} else {
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return aVirtualCursor[aMethod](rule);
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}
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}
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};
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