chrome/browser/resources/chromeos/chromevox/common/media_widget.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 goog.provide('cvox.ChromeVoxHTMLMediaWidget');
   6
   7 /**
   8  * @fileoverview Gives the user spoken feedback as they interact with the HTML5
   9  * media widgets (<video> and <audio>) + makes the widget keyboard accessible.
  10  *
  11  */
  12
  13 /**
  14  * A class containing the information needed to speak
  15  * a media element to the user.
  16  *
  17  * @constructor
  18  * @param {Element} mediaElem The media widget element.
  19  * @param {cvox.TtsInterface} tts The TTS object from ChromeVox.
  20  */
  21 cvox.ChromeVoxHTMLMediaWidget = function(mediaElem, tts){
  22   var self = this;
  23   this.mediaElem_ = mediaElem;
  24   this.mediaTts_ = tts;
  25
  26   this.keyListener_ = function(evt) {
  27     self.eventHandler_(evt);
  28   }
  29   this.blurListener_ = function(evt) {
  30     self.shutdown();
  31   }
  32
  33   this.mediaElem_.addEventListener('keydown', this.keyListener_, false);
  34   this.mediaElem_.addEventListener('keyup', this.keyListener_, false);
  35   this.mediaElem_.addEventListener('blur', this.blurListener_, false);
  36 };
  37
  38 /**
  39  * Removes the key listeners for the media widget.
  40  */
  41 cvox.ChromeVoxHTMLMediaWidget.prototype.shutdown = function() {
  42   this.mediaElem_.removeEventListener('blur', this.blurListener_, false);
  43   this.mediaElem_.removeEventListener('keydown', this.keyListener_, false);
  44   this.mediaElem_.removeEventListener('keyup', this.keyListener_, false);
  45 };
  46
  47 cvox.ChromeVoxHTMLMediaWidget.prototype.jumpToTime_ = function(targetTime) {
  48   if (targetTime < 0) {
  49     targetTime = 0;
  50   }
  51   if (targetTime > this.mediaElem_.duration) {
  52     targetTime = this.mediaElem_.duration;
  53   }
  54   this.mediaElem_.currentTime = targetTime;
  55 };
  56
  57 cvox.ChromeVoxHTMLMediaWidget.prototype.setVolume_ = function(targetVolume) {
  58   if (targetVolume < 0) {
  59     targetVolume = 0;
  60   }
  61   if (targetVolume > 1.0) {
  62     targetVolume = 1.0;
  63   }
  64   this.mediaElem_.volume = targetVolume;
  65 };
  66
  67 /**
  68  * Adds basic keyboard handlers to the media widget.
  69  */
  70 cvox.ChromeVoxHTMLMediaWidget.prototype.eventHandler_ = function(evt) {
  71   if (evt.type == 'keydown') {
  72     // Space/Enter for play/pause toggle.
  73     if ((evt.keyCode == 13) || (evt.keyCode == 32)) {
  74       if (this.mediaElem_.paused){
  75         this.mediaElem_.play();
  76       } else {
  77         this.mediaElem_.pause();
  78       }
  79     } else if (evt.keyCode == 39) { // Right - FF
  80       this.jumpToTime_(
  81           this.mediaElem_.currentTime + (this.mediaElem_.duration/10));
  82     } else if (evt.keyCode == 37) { // Left - REW
  83       this.jumpToTime_(
  84           this.mediaElem_.currentTime - (this.mediaElem_.duration/10));
  85     } else if (evt.keyCode == 38) { // Up - Vol. Up
  86       this.setVolume_(this.mediaElem_.volume + .1);
  87     } else if (evt.keyCode == 40) { // Down - Vol. Down
  88       this.setVolume_(this.mediaElem_.volume - .1);
  89     }
  90   }
  91 };