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      1 // Copyright (c) 2012 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 // These must match with how the video and canvas tags are declared in html.
      6 const VIDEO_TAG_WIDTH = 320;
      7 const VIDEO_TAG_HEIGHT = 240;
      8 
      9 // Number of test events to occur before the test pass. When the test pass,
     10 // the function gAllEventsOccured is called.
     11 var gNumberOfExpectedEvents = 0;
     12 
     13 // Number of events that currently have occurred.
     14 var gNumberOfEvents = 0;
     15 
     16 var gAllEventsOccured = function () {};
     17 
     18 // Use this function to set a function that will be called once all expected
     19 // events has occurred.
     20 function setAllEventsOccuredHandler(handler) {
     21   gAllEventsOccured = handler;
     22 }
     23 
     24 function detectVideoIn(videoElementName, callback) {
     25   var width = VIDEO_TAG_WIDTH;
     26   var height = VIDEO_TAG_HEIGHT;
     27   var videoElement = $(videoElementName);
     28   var canvas = $(videoElementName + '-canvas');
     29   var waitVideo = setInterval(function() {
     30     var context = canvas.getContext('2d');
     31     context.drawImage(videoElement, 0, 0, width, height);
     32     var pixels = context.getImageData(0, 0, width, height).data;
     33 
     34     if (isVideoPlaying(pixels, width, height)) {
     35       clearInterval(waitVideo);
     36       callback();
     37     }
     38   }, 100);
     39 }
     40 
     41 function waitForVideo(videoElement) {
     42   document.title = 'Waiting for video...';
     43   addExpectedEvent();
     44   detectVideoIn(videoElement, function () { eventOccured(); });
     45 }
     46 
     47 function waitForConnectionToStabilize(peerConnection) {
     48   addExpectedEvent();
     49   var waitForStabilization = setInterval(function() {
     50     if (peerConnection.signalingState == 'stable') {
     51       clearInterval(waitForStabilization);
     52       eventOccured();
     53     }
     54   }, 100);
     55 }
     56 
     57 function addExpectedEvent() {
     58   ++gNumberOfExpectedEvents;
     59 }
     60 
     61 function eventOccured() {
     62   ++gNumberOfEvents;
     63   if (gNumberOfEvents == gNumberOfExpectedEvents) {
     64     gAllEventsOccured();
     65   }
     66 }
     67 
     68 // This very basic video verification algorithm will be satisfied if any
     69 // pixels are nonzero in a small sample area in the middle. It relies on the
     70 // assumption that a video element with null source just presents zeroes.
     71 function isVideoPlaying(pixels, width, height) {
     72   // Sample somewhere near the middle of the image.
     73   var middle = width * height / 2;
     74   for (var i = 0; i < 20; i++) {
     75     if (pixels[middle + i] > 0) {
     76       return true;
     77     }
     78   }
     79   return false;
     80 }
     81 
     82 // This function matches |left| and |right| and throws an exception if the
     83 // values don't match.
     84 function expectEquals(left, right) {
     85   if (left != right) {
     86     var s = "expectEquals failed left: " + left + " right: " + right;
     87     document.title = s;
     88     throw s;
     89   }
     90 }