third_party/WebKit/LayoutTests/fast/canvas/canvas-resize-after-paint-without-layout.html

   1 <!DOCTYPE html>
   2 <!-- Check that resizing a (potentially accelerated) canvas properly clears its
   3      contents even if the layout size of the canvas does not change. Expected
   4      output is a blank canvas.
   5      https://bugs.webkit.org/show_bug.cgi?id=80871 -->
   6 <html>
   7   <head>
   8     <style>
   9       #canvas {
  10         outline: solid 1px black;
  11         width: 300px;
  12         height: 300px;
  13       }
  14     </style>
  15     <script src="../../resources/run-after-layout-and-paint.js"></script>
  16     <script>
  17       if (window.testRunner) {
  18         testRunner.dumpAsTextWithPixelResults();
  19         testRunner.waitUntilDone();
  20       }
  21
  22       function runTest() {
  23         var canvas = document.getElementById('canvas');
  24         var ctx = canvas.getContext('2d');
  25         ctx.fillStyle = 'red';
  26         ctx.fillRect(0, 0, 300, 300);
  27         runAfterLayoutAndPaint(repaintTest);
  28       }
  29
  30       function repaintTest() {
  31         var canvas = document.getElementById('canvas');
  32         // This changes the resolution of the canvas but keeps its layout size constant.
  33         canvas.width = canvas.width / 2;
  34         if (window.testRunner)
  35           testRunner.notifyDone();
  36       }
  37     </script>
  38   </head>
  39   <body onload="runTest();">
  40     <canvas id="canvas" width="300" height="300"/>
  41   </body>
  42 </html>