chrome/browser/resources/chromeos/chromevox/walkers/math_shifter.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 A class for walking mathml expressions.
   7  */
   8
   9 goog.provide('cvox.MathShifter');
  10
  11 goog.require('cvox.AbstractShifter');
  12 goog.require('cvox.BrailleUtil');
  13 goog.require('cvox.CursorSelection');
  14 goog.require('cvox.DomUtil');
  15 goog.require('cvox.MathmlStore');
  16 goog.require('cvox.MathmlStoreRules');
  17 goog.require('cvox.NavDescription');
  18 goog.require('cvox.SpeechRuleEngine');
  19 goog.require('cvox.TraverseMath');
  20
  21
  22 /**
  23  * @constructor
  24  * @extends {cvox.AbstractShifter}
  25  * @param {cvox.CursorSelection=} sel A cursor selection.
  26  */
  27 cvox.MathShifter = function(sel) {
  28   goog.base(this);
  29
  30   /**
  31    * Indicates the depth of the currently read expression.
  32    * @type {number}
  33    * @private
  34    */
  35   this.level_ = 0;
  36
  37   /**
  38    * Indicates the vertical direction of movement (true for up, false for down).
  39    * @type {boolean}
  40    * @private
  41    */
  42   this.direction_ = false;
  43
  44   /**
  45    * Indicates whether or not we've bumped against an edge in the math
  46    * structure.
  47    * @private
  48    */
  49   this.bumped_ = false;
  50
  51 cvox.TraverseMath.getInstance().initialize(sel.start.node);
  52 };
  53 goog.inherits(cvox.MathShifter, cvox.AbstractShifter);
  54
  55
  56 /**
  57  * @override
  58  */
  59 cvox.MathShifter.prototype.next = function(sel) {
  60   // Delegate to TraverseMath which manages selection inside of the math tree.
  61   var r = sel.isReversed();
  62   this.bumped_ = !cvox.TraverseMath.getInstance().nextSibling(r);
  63   var attachedNode = cvox.TraverseMath.getInstance().getAttachedActiveNode();
  64   return attachedNode ? cvox.CursorSelection.fromNode(attachedNode) : sel;
  65 };
  66
  67
  68 /**
  69  * @override
  70  */
  71 cvox.MathShifter.prototype.sync = function(sel) {
  72   var attachedNode = cvox.TraverseMath.getInstance().getAttachedActiveNode();
  73   return attachedNode ? cvox.CursorSelection.fromNode(attachedNode) : sel;
  74 };
  75
  76
  77 /**
  78  * @override
  79  */
  80 cvox.MathShifter.prototype.getName = function() {
  81   return cvox.ChromeVox.msgs.getMsg('math_shifter');
  82 };
  83
  84
  85 /**
  86  * @override
  87  */
  88 cvox.MathShifter.prototype.getDescription = function(prevSel, sel) {
  89   var descs = cvox.SpeechRuleEngine.getInstance().evaluateNode(
  90       cvox.TraverseMath.getInstance().activeNode);
  91   if (this.bumped_ && descs.length > 0) {
  92     descs[0].pushEarcon(cvox.Earcon.WRAP_EDGE);
  93   }
  94   return descs;
  95 };
  96
  97
  98 /**
  99  * @override
 100  */
 101 cvox.MathShifter.prototype.getBraille = function(prevSel, sel) {
 102   return new cvox.NavBraille({
 103     text: cvox.BrailleUtil.getTemplated(prevSel.start.node, sel.start.node)
 104   });
 105 };
 106
 107
 108 /**
 109  * @override
 110  */
 111 cvox.MathShifter.prototype.getGranularityMsg = function() {
 112   return this.direction_ ? 'up to level ' + this.level_ :
 113       'down to level ' + this.level_;
 114 };
 115
 116
 117 /**
 118  * @override
 119  */
 120 cvox.MathShifter.prototype.makeLessGranular = function() {
 121   this.level_ = this.level_ > 0 ? this.level_ - 1 : 0;
 122   this.direction_ = true;
 123   this.bumped_ = !cvox.TraverseMath.getInstance().nextParentChild(true);
 124 };
 125
 126
 127 /**
 128  * @override
 129  */
 130 cvox.MathShifter.prototype.makeMoreGranular = function() {
 131   this.direction_ = false;
 132   this.bumped_ = !cvox.TraverseMath.getInstance().nextParentChild(false);
 133   if (!this.bumped_) {
 134     this.level_++;
 135   }
 136 };
 137
 138
 139 /**
 140  * @override
 141  */
 142 cvox.MathShifter.create = function(sel) {
 143   if (cvox.DomPredicates.mathPredicate(
 144       cvox.DomUtil.getAncestors(sel.start.node))) {
 145     var mathNode = cvox.DomUtil.getContainingMath(sel.end.node);
 146     cvox.TraverseMath.getInstance().initialize(mathNode);
 147     cvox.SpeechRuleEngine.getInstance().parameterize(
 148         cvox.MathmlStore.getInstance());
 149     // TODO (sorge) Embed these changes into a local context menu/options menu.
 150     var dynamicCstr = cvox.MathStore.createDynamicConstraint(
 151         cvox.TraverseMath.getInstance().domain,
 152         cvox.TraverseMath.getInstance().style);
 153     cvox.SpeechRuleEngine.getInstance().setDynamicConstraint(dynamicCstr);
 154     return new cvox.MathShifter(sel);
 155   }
 156   return null;
 157 };
 158
 159
 160 /**
 161  * The active domain of the MathShifter.
 162  *
 163  * @return {string} The name of the current Math Domain.
 164  */
 165 cvox.MathShifter.prototype.getDomainMsg = function() {
 166   return cvox.TraverseMath.getInstance().domain;
 167 };