chrome/test/data/image_decoding/image_decoding.js

   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 // Run benchmark for at least this many milliseconds.
   6 var minTotalTimeMs = 10 * 1000;
   7 // Run benchmark at least this many times.
   8 var minIterations = 5;
   9 // Discard results for this many milliseconds after startup.
  10 var warmUpTimeMs = 1000;
  11 var benchmarkStartTime;
  12 var loadStartTimeMs;
  13 var loadingTimesMs = [];
  14 var isDone = false;
  15 var img;
  16
  17 var now = (function() {
  18   if (window.performance)
  19     return (window.performance.now ||
  20             window.performance.webkitNow).bind(window.performance);
  21   return Date.now.bind(window);
  22 })();
  23
  24 getImageFormat = function() {
  25   if (document.location.search) {
  26     return document.location.search.substr(1);
  27   }
  28   return "jpg";
  29 }
  30
  31 prepareImageElement = function() {
  32   img = document.createElement('img');
  33   // Scale the image down to the display size to make sure the entire image is
  34   // decoded. If the image is much larger than the display, some browsers might
  35   // only decode the visible portion of the image, which would skew the results
  36   // of this test.
  37   img.setAttribute('width', '100%');
  38   img.setAttribute('height', '100%');
  39   document.body.appendChild(img);
  40   console.log("Running benchmark for at least " + minTotalTimeMs +
  41               " ms and at least " + minIterations + " times.");
  42   document.getElementById('status').innerHTML = "Benchmark running.";
  43   setStatus(getImageFormat().toUpperCase() + " benchmark running.");
  44   benchmarkStartTimeMs = now();
  45 }
  46
  47 setStatus = function(status) {
  48   document.getElementById('status').innerHTML = status;
  49 }
  50
  51 runBenchmark = function() {
  52   setStatus("Preparing benchmark.");
  53   prepareImageElement();
  54   startLoadingImage();
  55 }
  56
  57 var iteration = (new Date).getTime();
  58
  59 startLoadingImage = function() {
  60   img.style.display = 'none';
  61   img.setAttribute('onload', '');
  62   img.setAttribute('src', '');
  63   img.addEventListener('load', onImageLoaded);
  64
  65   // Setting 'src' and 'display' above causes a repaint. Let it finish before
  66   // loading a new image. Ensures loading and painting don't overlap.
  67   requestAnimationFrame(function() {
  68     loadStartTimeMs = now();
  69     // Use a unique URL for each test iteration to work around image caching.
  70     img.setAttribute('src', 'droids.' + getImageFormat() + '?' + iteration);
  71     iteration += 1;
  72   });
  73 }
  74
  75 var requestAnimationFrame = (function() {
  76   return window.requestAnimationFrame       ||
  77          window.webkitRequestAnimationFrame ||
  78          window.mozRequestAnimationFrame    ||
  79          window.oRequestAnimationFrame      ||
  80          window.msRequestAnimationFrame     ||
  81          function(callback) {
  82            window.setTimeout(callback, 1000 / 60);
  83          };
  84 })().bind(window);
  85
  86 onImageLoaded = function() {
  87   var nowMs = now();
  88   var loadingTimeMs = nowMs - loadStartTimeMs;
  89   if (nowMs - benchmarkStartTimeMs >= warmUpTimeMs) {
  90     loadingTimesMs.push(loadingTimeMs);
  91   }
  92   if (nowMs - benchmarkStartTimeMs < minTotalTimeMs ||
  93       loadingTimesMs.length < minIterations) {
  94     // Repaint happens right after the image is loaded. Make sure painting
  95     // is completed before making the image visible. Setting the image to
  96     // visible will start decoding. After decoding and painting are completed
  97     // we'll start next test iteration.
  98     // Double rAF is needed here otherwise the image is barely visible.
  99     requestAnimationFrame(function() {
 100       img.style.display = '';
 101       requestAnimationFrame(startLoadingImage);
 102     });
 103   } else {
 104     isDone = true;
 105     console.log("loadingTimes: " + loadingTimesMs);
 106     setStatus(getImageFormat().toUpperCase() + " benchmark finished: " +
 107               loadingTimesMs);
 108   }
 109 }
 110
 111 averageLoadingTimeMs = function() {
 112   if (!loadingTimesMs.length)
 113     return 0;
 114   var total = 0;
 115   for (var i = 0; i < loadingTimesMs.length; ++i) {
 116     total += loadingTimesMs[i];
 117   }
 118   return total / loadingTimesMs.length;
 119 }