third_party/WebKit/LayoutTests/fast/images/rgb-jpeg-endian-pixels.html

   1 <!DOCTYPE html>
   2 JPEG image RGB pixels should render without color corruption and in strict<br>
   3 order, regardless of the underlying machine pixel buffer endianess.<br><br>
   4
   5 <img src="resources/rgb-jpeg-red.jpg"   onload="test(this, [255,0,0,255])">
   6 <img src="resources/rgb-jpeg-green.jpg" onload="test(this, [0,255,0,255])">
   7 <img src="resources/rgb-jpeg-blue.jpg"  onload="test(this, [0,0,255,255])">
   8
   9 <pre id="log">PASS</pre>
  10
  11 <script>
  12 if (window.testRunner) {
  13     window.testRunner.waitUntilDone();
  14     window.testRunner.dumpAsText();
  15 }
  16
  17 function log(message)
  18 {
  19     document.getElementById("log").textContent += '\n' + message;
  20 }
  21
  22 function averagePixelComponents(data, size)
  23 {
  24     var r = 0, g = 0, b = 0, a = 0;
  25     for (var i = 0, total = size * 4; i < total; i += 4) {
  26         r += data[i + 0];
  27         g += data[i + 1];
  28         b += data[i + 2];
  29         a += data[i + 3];
  30     }
  31
  32     return [r / size, g / size, b / size, a / size];
  33 }
  34
  35 function averagePixelShouldBe(pixel, expect, tolerance)
  36 {
  37     var delta = 0;
  38     pixel.forEach(function(component, i) {
  39         delta = Math.max(Math.abs(pixel[i] - expect[i]), delta);
  40     });
  41
  42     if (delta > tolerance)
  43        log('FAIL: [' + pixel + '] expected [' + expect + '] +/- ' + tolerance);
  44 }
  45
  46 function testImage(image, expect)
  47 {
  48     // Create a canvas, load the given image in it.
  49     var canvas = document.createElement("canvas");
  50     canvas.width = canvas.height = 64;
  51     var context = canvas.getContext("2d");
  52     context.drawImage(image, 0, 0);
  53
  54     // Compare the canvas pixel component averages.
  55     var pixels = context.getImageData(0, 0, 64, 64).data;
  56     var result = averagePixelComponents(pixels, 64 * 64);
  57
  58     var pixelTolerance = 3;
  59     averagePixelShouldBe(result, expect, pixelTolerance);
  60 }
  61
  62 function test(image, expect)
  63 {
  64     try {
  65         loadedImages = window.loadedImages || 0;
  66         testImage(image, expect);
  67         if (++loadedImages < 3)
  68             return;
  69     } catch (e) {
  70         log('FAIL: ' + e.message);
  71     }
  72
  73     if (window.testRunner)
  74         window.testRunner.notifyDone();
  75 }
  76 </script>