gecko-dev/accessible/jsat/AccessFu.jsm

/* 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/. */

/* global AccessFu, Components, Utils, PrefCache, Logger, Services,
          PointerAdapter, dump, Presentation, Rect */
/* exported AccessFu */

'use strict';

const {utils: Cu, interfaces: Ci} = Components;

this.EXPORTED_SYMBOLS = ['AccessFu']; // jshint ignore:line

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

const ACCESSFU_DISABLE = 0; // jshint ignore:line
const ACCESSFU_ENABLE = 1;
const ACCESSFU_AUTO = 2;

const SCREENREADER_SETTING = 'accessibility.screenreader';
const QUICKNAV_MODES_PREF = 'accessibility.accessfu.quicknav_modes';
const QUICKNAV_INDEX_PREF = 'accessibility.accessfu.quicknav_index';

this.AccessFu = { // jshint ignore:line
  /**
   * Initialize chrome-layer accessibility functionality.
   * If accessibility is enabled on the platform, then a special accessibility
   * mode is started.
   */
  attach: function attach(aWindow) {
    Utils.init(aWindow);

    try {
      Services.androidBridge.dispatch('Accessibility:Ready');
      Services.obs.addObserver(this, 'Accessibility:Settings', false);
    } catch (x) {
      // Not on Android
      if (aWindow.navigator.mozSettings) {
        let lock = aWindow.navigator.mozSettings.createLock();
        let req = lock.get(SCREENREADER_SETTING);
        req.addEventListener('success', () => {
          this._systemPref = req.result[SCREENREADER_SETTING];
          this._enableOrDisable();
        });
        aWindow.navigator.mozSettings.addObserver(
          SCREENREADER_SETTING, this.handleEvent);
      }
    }

    this._activatePref = new PrefCache(
      'accessibility.accessfu.activate', this._enableOrDisable.bind(this));

    this._enableOrDisable();
  },

  /**
   * Shut down chrome-layer accessibility functionality from the outside.
   */
  detach: function detach() {
    // Avoid disabling twice.
    if (this._enabled) {
      this._disable();
    }
    if (Utils.MozBuildApp === 'mobile/android') {
      Services.obs.removeObserver(this, 'Accessibility:Settings');
    } else if (Utils.win.navigator.mozSettings) {
      Utils.win.navigator.mozSettings.removeObserver(
        SCREENREADER_SETTING, this.handleEvent);
    }
    delete this._activatePref;
    Utils.uninit();
  },

  /**
   * A lazy getter for event handler that binds the scope to AccessFu object.
   */
  get handleEvent() {
    delete this.handleEvent;
    this.handleEvent = this._handleEvent.bind(this);
    return this.handleEvent;
  },

  /**
   * Start AccessFu mode, this primarily means controlling the virtual cursor
   * with arrow keys.
   */
  _enable: function _enable() {
    if (this._enabled) {
      return;
    }
    this._enabled = true;

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

    for (let mm of Utils.AllMessageManagers) {
      this._addMessageListeners(mm);
      this._loadFrameScript(mm);
    }

    // Add stylesheet
    let stylesheetURL = 'chrome://global/content/accessibility/AccessFu.css';
    let stylesheet = Utils.win.document.createProcessingInstruction(
      'xml-stylesheet', 'href="' + stylesheetURL + '" type="text/css"');
    Utils.win.document.insertBefore(stylesheet, Utils.win.document.firstChild);
    this.stylesheet = Cu.getWeakReference(stylesheet);


    // Populate quicknav modes
    this._quicknavModesPref =
      new PrefCache(QUICKNAV_MODES_PREF, (aName, aValue, aFirstRun) => {
        this.Input.quickNavMode.updateModes(aValue);
        if (!aFirstRun) {
          // If the modes change, reset the current mode index to 0.
          Services.prefs.setIntPref(QUICKNAV_INDEX_PREF, 0);
        }
      }, true);

    this._quicknavCurrentModePref =
      new PrefCache(QUICKNAV_INDEX_PREF, (aName, aValue) => {
        this.Input.quickNavMode.updateCurrentMode(Number(aValue));
      }, true);

    // Check for output notification
    this._notifyOutputPref =
      new PrefCache('accessibility.accessfu.notify_output');


    this.Input.start();
    Output.start();
    PointerAdapter.start();

    Services.obs.addObserver(this, 'remote-browser-shown', false);
    Services.obs.addObserver(this, 'inprocess-browser-shown', false);
    Services.obs.addObserver(this, 'Accessibility:NextObject', false);
    Services.obs.addObserver(this, 'Accessibility:PreviousObject', false);
    Services.obs.addObserver(this, 'Accessibility:Focus', false);
    Services.obs.addObserver(this, 'Accessibility:ActivateObject', false);
    Services.obs.addObserver(this, 'Accessibility:LongPress', false);
    Services.obs.addObserver(this, 'Accessibility:ScrollForward', false);
    Services.obs.addObserver(this, 'Accessibility:ScrollBackward', false);
    Services.obs.addObserver(this, 'Accessibility:MoveByGranularity', false);
    Utils.win.addEventListener('TabOpen', this);
    Utils.win.addEventListener('TabClose', this);
    Utils.win.addEventListener('TabSelect', this);

    if (this.readyCallback) {
      this.readyCallback();
      delete this.readyCallback;
    }

    Logger.info('AccessFu:Enabled');
  },

  /**
   * Disable AccessFu and return to default interaction mode.
   */
  _disable: function _disable() {
    if (!this._enabled) {
      return;
    }

    this._enabled = false;

    Utils.win.document.removeChild(this.stylesheet.get());

    for (let mm of Utils.AllMessageManagers) {
      mm.sendAsyncMessage('AccessFu:Stop');
      this._removeMessageListeners(mm);
    }

    this.Input.stop();
    Output.stop();
    PointerAdapter.stop();

    Utils.win.removeEventListener('TabOpen', this);
    Utils.win.removeEventListener('TabClose', this);
    Utils.win.removeEventListener('TabSelect', this);

    Services.obs.removeObserver(this, 'remote-browser-shown');
    Services.obs.removeObserver(this, 'inprocess-browser-shown');
    Services.obs.removeObserver(this, 'Accessibility:NextObject');
    Services.obs.removeObserver(this, 'Accessibility:PreviousObject');
    Services.obs.removeObserver(this, 'Accessibility:Focus');
    Services.obs.removeObserver(this, 'Accessibility:ActivateObject');
    Services.obs.removeObserver(this, 'Accessibility:LongPress');
    Services.obs.removeObserver(this, 'Accessibility:ScrollForward');
    Services.obs.removeObserver(this, 'Accessibility:ScrollBackward');
    Services.obs.removeObserver(this, 'Accessibility:MoveByGranularity');

    delete this._quicknavModesPref;
    delete this._notifyOutputPref;

    if (this.doneCallback) {
      this.doneCallback();
      delete this.doneCallback;
    }

    Logger.info('AccessFu:Disabled');
  },

  _enableOrDisable: function _enableOrDisable() {
    try {
      if (!this._activatePref) {
        return;
      }
      let activatePref = this._activatePref.value;
      if (activatePref == ACCESSFU_ENABLE ||
          this._systemPref && activatePref == ACCESSFU_AUTO) {
        this._enable();
      } else {
        this._disable();
      }
    } catch (x) {
      dump('Error ' + x.message + ' ' + x.fileName + ':' + x.lineNumber);
    }
  },

  receiveMessage: function receiveMessage(aMessage) {
    Logger.debug(() => {
      return ['Recieved', aMessage.name, JSON.stringify(aMessage.json)];
    });

    switch (aMessage.name) {
      case 'AccessFu:Ready':
        let mm = Utils.getMessageManager(aMessage.target);
        if (this._enabled) {
          mm.sendAsyncMessage('AccessFu:Start',
                              {method: 'start', buildApp: Utils.MozBuildApp});
        }
        break;
      case 'AccessFu:Present':
        this._output(aMessage.json, aMessage.target);
        break;
      case 'AccessFu:Input':
        this.Input.setEditState(aMessage.json);
        break;
      case 'AccessFu:DoScroll':
        this.Input.doScroll(aMessage.json);
        break;
    }
  },

  _output: function _output(aPresentationData, aBrowser) {
    if (!Utils.isAliveAndVisible(
      Utils.AccService.getAccessibleFor(aBrowser))) {
      return;
    }
    for (let presenter of aPresentationData) {
      if (!presenter) {
        continue;
      }

      try {
        Output[presenter.type](presenter.details, aBrowser);
      } catch (x) {
        Logger.logException(x);
      }
    }

    if (this._notifyOutputPref.value) {
      Services.obs.notifyObservers(null, 'accessibility-output',
                                   JSON.stringify(aPresentationData));
    }
  },

  _loadFrameScript: function _loadFrameScript(aMessageManager) {
    if (this._processedMessageManagers.indexOf(aMessageManager) < 0) {
      aMessageManager.loadFrameScript(
        'chrome://global/content/accessibility/content-script.js', true);
      this._processedMessageManagers.push(aMessageManager);
    } else if (this._enabled) {
      // If the content-script is already loaded and AccessFu is enabled,
      // send an AccessFu:Start message.
      aMessageManager.sendAsyncMessage('AccessFu:Start',
        {method: 'start', buildApp: Utils.MozBuildApp});
    }
  },

  _addMessageListeners: function _addMessageListeners(aMessageManager) {
    aMessageManager.addMessageListener('AccessFu:Present', this);
    aMessageManager.addMessageListener('AccessFu:Input', this);
    aMessageManager.addMessageListener('AccessFu:Ready', this);
    aMessageManager.addMessageListener('AccessFu:DoScroll', this);
  },

  _removeMessageListeners: function _removeMessageListeners(aMessageManager) {
    aMessageManager.removeMessageListener('AccessFu:Present', this);
    aMessageManager.removeMessageListener('AccessFu:Input', this);
    aMessageManager.removeMessageListener('AccessFu:Ready', this);
    aMessageManager.removeMessageListener('AccessFu:DoScroll', this);
  },

  _handleMessageManager: function _handleMessageManager(aMessageManager) {
    if (this._enabled) {
      this._addMessageListeners(aMessageManager);
    }
    this._loadFrameScript(aMessageManager);
  },

  observe: function observe(aSubject, aTopic, aData) {
    switch (aTopic) {
      case 'Accessibility:Settings':
        this._systemPref = JSON.parse(aData).enabled;
        this._enableOrDisable();
        break;
      case 'Accessibility:NextObject':
      case 'Accessibility:PreviousObject':
      {
        let rule = aData ?
          aData.substr(0, 1).toUpperCase() + aData.substr(1).toLowerCase() :
          'Simple';
        let method = aTopic.replace(/Accessibility:(\w+)Object/, 'move$1');
        this.Input.moveCursor(method, rule, 'gesture');
        break;
      }
      case 'Accessibility:ActivateObject':
        this.Input.activateCurrent(JSON.parse(aData));
        break;
      case 'Accessibility:LongPress':
        this.Input.sendContextMenuMessage();
        break;
      case 'Accessibility:ScrollForward':
        this.Input.androidScroll('forward');
        break;
      case 'Accessibility:ScrollBackward':
        this.Input.androidScroll('backward');
        break;
      case 'Accessibility:Focus':
        this._focused = JSON.parse(aData);
        if (this._focused) {
          this.autoMove({ forcePresent: true, noOpIfOnScreen: true });
        }
        break;
      case 'Accessibility:MoveByGranularity':
        this.Input.moveByGranularity(JSON.parse(aData));
        break;
      case 'remote-browser-shown':
      case 'inprocess-browser-shown':
      {
        // Ignore notifications that aren't from a Browser
        let frameLoader = aSubject.QueryInterface(Ci.nsIFrameLoader);
        if (!frameLoader.ownerIsMozBrowserFrame) {
          return;
        }
        this._handleMessageManager(frameLoader.messageManager);
        break;
      }
    }
  },

  _handleEvent: function _handleEvent(aEvent) {
    switch (aEvent.type) {
      case 'TabOpen':
      {
        let mm = Utils.getMessageManager(aEvent.target);
        this._handleMessageManager(mm);
        break;
      }
      case 'TabClose':
      {
        let mm = Utils.getMessageManager(aEvent.target);
        let mmIndex = this._processedMessageManagers.indexOf(mm);
        if (mmIndex > -1) {
          this._removeMessageListeners(mm);
          this._processedMessageManagers.splice(mmIndex, 1);
        }
        break;
      }
      case 'TabSelect':
      {
        if (this._focused) {
          // We delay this for half a second so the awesomebar could close,
          // and we could use the current coordinates for the content item.
          // XXX TODO figure out how to avoid magic wait here.
	  this.autoMove({
	    delay: 500,
	    forcePresent: true,
	    noOpIfOnScreen: true,
	    moveMethod: 'moveFirst' });
        }
        break;
      }
      default:
      {
        // A settings change, it does not have an event type
        if (aEvent.settingName == SCREENREADER_SETTING) {
          this._systemPref = aEvent.settingValue;
          this._enableOrDisable();
        }
        break;
      }
    }
  },

  autoMove: function autoMove(aOptions) {
    let mm = Utils.getMessageManager(Utils.CurrentBrowser);
    mm.sendAsyncMessage('AccessFu:AutoMove', aOptions);
  },

  announce: function announce(aAnnouncement) {
    this._output(Presentation.announce(aAnnouncement), Utils.CurrentBrowser);
  },

  // So we don't enable/disable twice
  _enabled: false,

  // Layerview is focused
  _focused: false,

  // Keep track of message managers tha already have a 'content-script.js'
  // injected.
  _processedMessageManagers: [],

  /**
   * Adjusts the given bounds relative to the given browser.
   * @param {Rect} aJsonBounds the bounds to adjust
   * @param {browser} aBrowser the browser we want the bounds relative to
   * @param {bool} aToCSSPixels whether to convert to CSS pixels (as opposed to
   *               device pixels)
   */
  adjustContentBounds:
    function(aJsonBounds, aBrowser, aToCSSPixels) {
      let bounds = new Rect(aJsonBounds.left, aJsonBounds.top,
                            aJsonBounds.right - aJsonBounds.left,
                            aJsonBounds.bottom - aJsonBounds.top);
      let win = Utils.win;
      let dpr = win.devicePixelRatio;
      let offset = { left: -win.mozInnerScreenX, top: -win.mozInnerScreenY };

      // Add the offset; the offset is in CSS pixels, so multiply the
      // devicePixelRatio back in before adding to preserve unit consistency.
      bounds = bounds.translate(offset.left * dpr, offset.top * dpr);

      // If we want to get to CSS pixels from device pixels, this needs to be
      // further divided by the devicePixelRatio due to widget scaling.
      if (aToCSSPixels) {
        bounds = bounds.scale(1 / dpr, 1 / dpr);
      }

      return bounds.expandToIntegers();
    }
};

var Output = {
  brailleState: {
    startOffset: 0,
    endOffset: 0,
    text: '',
    selectionStart: 0,
    selectionEnd: 0,

    init: function init(aOutput) {
      if (aOutput && 'output' in aOutput) {
        this.startOffset = aOutput.startOffset;
        this.endOffset = aOutput.endOffset;
        // We need to append a space at the end so that the routing key
        // corresponding to the end of the output (i.e. the space) can be hit to
        // move the caret there.
        this.text = aOutput.output + ' ';
        this.selectionStart = typeof aOutput.selectionStart === 'number' ?
                              aOutput.selectionStart : this.selectionStart;
        this.selectionEnd = typeof aOutput.selectionEnd === 'number' ?
                            aOutput.selectionEnd : this.selectionEnd;

        return { text: this.text,
                 selectionStart: this.selectionStart,
                 selectionEnd: this.selectionEnd };
      }

      return null;
    },

    adjustText: function adjustText(aText) {
      let newBraille = [];
      let braille = {};

      let prefix = this.text.substring(0, this.startOffset).trim();
      if (prefix) {
        prefix += ' ';
        newBraille.push(prefix);
      }

      newBraille.push(aText);

      let suffix = this.text.substring(this.endOffset).trim();
      if (suffix) {
        suffix = ' ' + suffix;
        newBraille.push(suffix);
      }

      this.startOffset = braille.startOffset = prefix.length;
      this.text = braille.text = newBraille.join('') + ' ';
      this.endOffset = braille.endOffset = braille.text.length - suffix.length;
      braille.selectionStart = this.selectionStart;
      braille.selectionEnd = this.selectionEnd;

      return braille;
    },

    adjustSelection: function adjustSelection(aSelection) {
      let braille = {};

      braille.startOffset = this.startOffset;
      braille.endOffset = this.endOffset;
      braille.text = this.text;
      this.selectionStart = braille.selectionStart =
        aSelection.selectionStart + this.startOffset;
      this.selectionEnd = braille.selectionEnd =
        aSelection.selectionEnd + this.startOffset;

      return braille;
    }
  },

  start: function start() {
    Cu.import('resource://gre/modules/Geometry.jsm');
  },

  stop: function stop() {
    if (this.highlightBox) {
      let highlightBox = this.highlightBox.get();
      if (highlightBox) {
        highlightBox.remove();
      }
      delete this.highlightBox;
    }
  },

  B2G: function B2G(aDetails) {
    Utils.dispatchChromeEvent('accessibility-output', aDetails);
  },

  Visual: function Visual(aDetail, aBrowser) {
    switch (aDetail.eventType) {
      case 'viewport-change':
      case 'vc-change':
      {
        let highlightBox = null;
        if (!this.highlightBox) {
          let doc = Utils.win.document;
          // Add highlight box
          highlightBox = Utils.win.document.
            createElementNS('http://www.w3.org/1999/xhtml', 'div');
          let parent = doc.body || doc.documentElement;
          parent.appendChild(highlightBox);
          highlightBox.id = 'virtual-cursor-box';

          // Add highlight inset for inner shadow
          highlightBox.appendChild(
            doc.createElementNS('http://www.w3.org/1999/xhtml', 'div'));

          this.highlightBox = Cu.getWeakReference(highlightBox);
        } else {
          highlightBox = this.highlightBox.get();
        }

        let padding = aDetail.padding;
        let r = AccessFu.adjustContentBounds(aDetail.bounds, aBrowser, true);

        // First hide it to avoid flickering when changing the style.
        highlightBox.classList.remove('show');
        highlightBox.style.top = (r.top - padding) + 'px';
        highlightBox.style.left = (r.left - padding) + 'px';
        highlightBox.style.width = (r.width + padding*2) + 'px';
        highlightBox.style.height = (r.height + padding*2) + 'px';
        highlightBox.classList.add('show');

        break;
      }
      case 'tabstate-change':
      {
        let highlightBox = this.highlightBox ? this.highlightBox.get() : null;
        if (highlightBox) {
          highlightBox.classList.remove('show');
        }
        break;
      }
    }
  },

  get androidBridge() {
    delete this.androidBridge;
    if (Utils.MozBuildApp === 'mobile/android') {
      this.androidBridge = Services.androidBridge;
    } else {
      this.androidBridge = null;
    }
    return this.androidBridge;
  },

  Android: function Android(aDetails, aBrowser) {
    const ANDROID_VIEW_TEXT_CHANGED = 0x10;
    const ANDROID_VIEW_TEXT_SELECTION_CHANGED = 0x2000;

    if (!this.androidBridge) {
      return;
    }

    for (let androidEvent of aDetails) {
      if (androidEvent.bounds) {
        androidEvent.bounds = AccessFu.adjustContentBounds(
          androidEvent.bounds, aBrowser);
      }

      switch(androidEvent.eventType) {
        case ANDROID_VIEW_TEXT_CHANGED:
          androidEvent.brailleOutput = this.brailleState.adjustText(
            androidEvent.text);
          break;
        case ANDROID_VIEW_TEXT_SELECTION_CHANGED:
          androidEvent.brailleOutput = this.brailleState.adjustSelection(
            androidEvent.brailleOutput);
          break;
        default:
          androidEvent.brailleOutput = this.brailleState.init(
            androidEvent.brailleOutput);
          break;
      }
      let win = Utils.win;
      let view = win && win.QueryInterface(Ci.nsIAndroidView);
      view.dispatch('Accessibility:Event', androidEvent);
    }
  },

  Braille: function Braille(aDetails) {
    Logger.debug('Braille output: ' + aDetails.output);
  }
};

var Input = {
  editState: {},

  start: function start() {
    // XXX: This is too disruptive on desktop for now.
    // Might need to add special modifiers.
    if (Utils.MozBuildApp != 'browser') {
      Utils.win.document.addEventListener('keypress', this, true);
    }
    Utils.win.addEventListener('mozAccessFuGesture', this, true);
  },

  stop: function stop() {
    if (Utils.MozBuildApp != 'browser') {
      Utils.win.document.removeEventListener('keypress', this, true);
    }
    Utils.win.removeEventListener('mozAccessFuGesture', this, true);
  },

  handleEvent: function Input_handleEvent(aEvent) {
    try {
      switch (aEvent.type) {
      case 'keypress':
        this._handleKeypress(aEvent);
        break;
      case 'mozAccessFuGesture':
        this._handleGesture(aEvent.detail);
        break;
      }
    } catch (x) {
      Logger.logException(x);
    }
  },

  _handleGesture: function _handleGesture(aGesture) {
    let gestureName = aGesture.type + aGesture.touches.length;
    Logger.debug('Gesture', aGesture.type,
                 '(fingers: ' + aGesture.touches.length + ')');

    switch (gestureName) {
      case 'dwell1':
      case 'explore1':
        this.moveToPoint('Simple', aGesture.touches[0].x,
          aGesture.touches[0].y);
        break;
      case 'doubletap1':
        this.activateCurrent();
        break;
      case 'doubletaphold1':
        Utils.dispatchChromeEvent('accessibility-control', 'quicknav-menu');
        break;
      case 'swiperight1':
        this.moveCursor('moveNext', 'Simple', 'gestures');
        break;
      case 'swipeleft1':
        this.moveCursor('movePrevious', 'Simple', 'gesture');
        break;
      case 'swipeup1':
        this.moveCursor(
          'movePrevious', this.quickNavMode.current, 'gesture', true);
        break;
      case 'swipedown1':
        this.moveCursor('moveNext', this.quickNavMode.current, 'gesture', true);
        break;
      case 'exploreend1':
      case 'dwellend1':
        this.activateCurrent(null, true);
        break;
      case 'swiperight2':
        if (aGesture.edge) {
          Utils.dispatchChromeEvent('accessibility-control',
            'edge-swipe-right');
          break;
        }
        this.sendScrollMessage(-1, true);
        break;
      case 'swipedown2':
        if (aGesture.edge) {
          Utils.dispatchChromeEvent('accessibility-control', 'edge-swipe-down');
          break;
        }
        this.sendScrollMessage(-1);
        break;
      case 'swipeleft2':
        if (aGesture.edge) {
          Utils.dispatchChromeEvent('accessibility-control', 'edge-swipe-left');
          break;
        }
        this.sendScrollMessage(1, true);
        break;
      case 'swipeup2':
        if (aGesture.edge) {
          Utils.dispatchChromeEvent('accessibility-control', 'edge-swipe-up');
          break;
        }
        this.sendScrollMessage(1);
        break;
      case 'explore2':
        Utils.CurrentBrowser.contentWindow.scrollBy(
          -aGesture.deltaX, -aGesture.deltaY);
        break;
      case 'swiperight3':
        this.moveCursor('moveNext', this.quickNavMode.current, 'gesture');
        break;
      case 'swipeleft3':
        this.moveCursor('movePrevious', this.quickNavMode.current, 'gesture');
        break;
      case 'swipedown3':
        this.quickNavMode.next();
        AccessFu.announce('quicknav_' + this.quickNavMode.current);
        break;
      case 'swipeup3':
        this.quickNavMode.previous();
        AccessFu.announce('quicknav_' + this.quickNavMode.current);
        break;
      case 'tripletap3':
        Utils.dispatchChromeEvent('accessibility-control', 'toggle-shade');
        break;
      case 'tap2':
        Utils.dispatchChromeEvent('accessibility-control', 'toggle-pause');
        break;
    }
  },

  _handleKeypress: function _handleKeypress(aEvent) {
    let target = aEvent.target;

    // Ignore keys with modifiers so the content could take advantage of them.
    if (aEvent.ctrlKey || aEvent.altKey || aEvent.metaKey) {
      return;
    }

    switch (aEvent.keyCode) {
      case 0:
        // an alphanumeric key was pressed, handle it separately.
        // If it was pressed with either alt or ctrl, just pass through.
        // If it was pressed with meta, pass the key on without the meta.
        if (this.editState.editing) {
          return;
        }

        let key = String.fromCharCode(aEvent.charCode);
        try {
          let [methodName, rule] = this.keyMap[key];
          this.moveCursor(methodName, rule, 'keyboard');
        } catch (x) {
          return;
        }
        break;
      case aEvent.DOM_VK_RIGHT:
        if (this.editState.editing) {
          if (!this.editState.atEnd) {
            // Don't move forward if caret is not at end of entry.
            // XXX: Fix for rtl
            return;
          } else {
            target.blur();
          }
        }
        this.moveCursor(aEvent.shiftKey ?
          'moveLast' : 'moveNext', 'Simple', 'keyboard');
        break;
      case aEvent.DOM_VK_LEFT:
        if (this.editState.editing) {
          if (!this.editState.atStart) {
            // Don't move backward if caret is not at start of entry.
            // XXX: Fix for rtl
            return;
          } else {
            target.blur();
          }
        }
        this.moveCursor(aEvent.shiftKey ?
          'moveFirst' : 'movePrevious', 'Simple', 'keyboard');
        break;
      case aEvent.DOM_VK_UP:
        if (this.editState.multiline) {
          if (!this.editState.atStart) {
            // Don't blur content if caret is not at start of text area.
            return;
          } else {
            target.blur();
          }
        }

        if (Utils.MozBuildApp == 'mobile/android') {
          // Return focus to native Android browser chrome.
          let win = Utils.win;
          let view = win && win.QueryInterface(Ci.nsIAndroidView);
          view.dispatch('ToggleChrome:Focus');
        }
        break;
      case aEvent.DOM_VK_RETURN:
        if (this.editState.editing) {
          return;
        }
        this.activateCurrent();
        break;
    default:
      return;
    }

    aEvent.preventDefault();
    aEvent.stopPropagation();
  },

  moveToPoint: function moveToPoint(aRule, aX, aY) {
    // XXX: Bug 1013408 - There is no alignment between the chrome window's
    // viewport size and the content viewport size in Android. This makes
    // sending mouse events beyond its bounds impossible.
    if (Utils.MozBuildApp === 'mobile/android') {
      let mm = Utils.getMessageManager(Utils.CurrentBrowser);
      mm.sendAsyncMessage('AccessFu:MoveToPoint',
        {rule: aRule, x: aX, y: aY, origin: 'top'});
    } else {
      let win = Utils.win;
      Utils.winUtils.sendMouseEvent('mousemove',
        aX - win.mozInnerScreenX, aY - win.mozInnerScreenY, 0, 0, 0);
    }
  },

  moveCursor: function moveCursor(aAction, aRule, aInputType, aAdjustRange) {
    let mm = Utils.getMessageManager(Utils.CurrentBrowser);
    mm.sendAsyncMessage('AccessFu:MoveCursor',
                        { action: aAction, rule: aRule,
                          origin: 'top', inputType: aInputType,
                          adjustRange: aAdjustRange });
  },

  androidScroll: function androidScroll(aDirection) {
    let mm = Utils.getMessageManager(Utils.CurrentBrowser);
    mm.sendAsyncMessage('AccessFu:AndroidScroll',
                        { direction: aDirection, origin: 'top' });
  },

  moveByGranularity: function moveByGranularity(aDetails) {
    const GRANULARITY_PARAGRAPH = 8;
    const GRANULARITY_LINE = 4;

    if (!this.editState.editing) {
      if (aDetails.granularity & (GRANULARITY_PARAGRAPH | GRANULARITY_LINE)) {
        this.moveCursor('move' + aDetails.direction, 'Simple', 'gesture');
        return;
      }
    } else {
      aDetails.atStart = this.editState.atStart;
      aDetails.atEnd = this.editState.atEnd;
    }

    let mm = Utils.getMessageManager(Utils.CurrentBrowser);
    let type = this.editState.editing ? 'AccessFu:MoveCaret' :
                                        'AccessFu:MoveByGranularity';
    mm.sendAsyncMessage(type, aDetails);
  },

  activateCurrent: function activateCurrent(aData, aActivateIfKey = false) {
    let mm = Utils.getMessageManager(Utils.CurrentBrowser);
    let offset = aData && typeof aData.keyIndex === 'number' ?
                 aData.keyIndex - Output.brailleState.startOffset : -1;

    mm.sendAsyncMessage('AccessFu:Activate',
                        {offset: offset, activateIfKey: aActivateIfKey});
  },

  sendContextMenuMessage: function sendContextMenuMessage() {
    let mm = Utils.getMessageManager(Utils.CurrentBrowser);
    mm.sendAsyncMessage('AccessFu:ContextMenu', {});
  },

  setEditState: function setEditState(aEditState) {
    Logger.debug(() => { return ['setEditState', JSON.stringify(aEditState)] });
    this.editState = aEditState;
  },

  // XXX: This is here for backwards compatability with screen reader simulator
  // it should be removed when the extension is updated on amo.
  scroll: function scroll(aPage, aHorizontal) {
    this.sendScrollMessage(aPage, aHorizontal);
  },

  sendScrollMessage: function sendScrollMessage(aPage, aHorizontal) {
    let mm = Utils.getMessageManager(Utils.CurrentBrowser);
    mm.sendAsyncMessage('AccessFu:Scroll',
      {page: aPage, horizontal: aHorizontal, origin: 'top'});
  },

  doScroll: function doScroll(aDetails) {
    let horizontal = aDetails.horizontal;
    let page = aDetails.page;
    let p = AccessFu.adjustContentBounds(
      aDetails.bounds, Utils.CurrentBrowser, true).center();
    Utils.winUtils.sendWheelEvent(p.x, p.y,
      horizontal ? page : 0, horizontal ? 0 : page, 0,
      Utils.win.WheelEvent.DOM_DELTA_PAGE, 0, 0, 0, 0);
  },

  get keyMap() {
    delete this.keyMap;
    this.keyMap = {
      a: ['moveNext', 'Anchor'],
      A: ['movePrevious', 'Anchor'],
      b: ['moveNext', 'Button'],
      B: ['movePrevious', 'Button'],
      c: ['moveNext', 'Combobox'],
      C: ['movePrevious', 'Combobox'],
      d: ['moveNext', 'Landmark'],
      D: ['movePrevious', 'Landmark'],
      e: ['moveNext', 'Entry'],
      E: ['movePrevious', 'Entry'],
      f: ['moveNext', 'FormElement'],
      F: ['movePrevious', 'FormElement'],
      g: ['moveNext', 'Graphic'],
      G: ['movePrevious', 'Graphic'],
      h: ['moveNext', 'Heading'],
      H: ['movePrevious', 'Heading'],
      i: ['moveNext', 'ListItem'],
      I: ['movePrevious', 'ListItem'],
      k: ['moveNext', 'Link'],
      K: ['movePrevious', 'Link'],
      l: ['moveNext', 'List'],
      L: ['movePrevious', 'List'],
      p: ['moveNext', 'PageTab'],
      P: ['movePrevious', 'PageTab'],
      r: ['moveNext', 'RadioButton'],
      R: ['movePrevious', 'RadioButton'],
      s: ['moveNext', 'Separator'],
      S: ['movePrevious', 'Separator'],
      t: ['moveNext', 'Table'],
      T: ['movePrevious', 'Table'],
      x: ['moveNext', 'Checkbox'],
      X: ['movePrevious', 'Checkbox']
    };

    return this.keyMap;
  },

  quickNavMode: {
    get current() {
      return this.modes[this._currentIndex];
    },

    previous: function quickNavMode_previous() {
      Services.prefs.setIntPref(QUICKNAV_INDEX_PREF,
        this._currentIndex > 0 ?
          this._currentIndex - 1 : this.modes.length - 1);
    },

    next: function quickNavMode_next() {
      Services.prefs.setIntPref(QUICKNAV_INDEX_PREF,
        this._currentIndex + 1 >= this.modes.length ?
          0 : this._currentIndex + 1);
    },

    updateModes: function updateModes(aModes) {
      if (aModes) {
        this.modes = aModes.split(',');
      } else {
        this.modes = [];
      }
    },

    updateCurrentMode: function updateCurrentMode(aModeIndex) {
      Logger.debug('Quicknav mode:', this.modes[aModeIndex]);
      this._currentIndex = aModeIndex;
    }
  }
};
AccessFu.Input = Input;