testing/web-platform/tests/imagebitmap-renderingcontext/tranferFromImageBitmap-null-offscreen.html

   1 <!DOCTYPE html>
   2 <meta charset="utf-8">
   3 <title>Canvas's ImageBitmapRenderingContext test</title>
   4 <script src="/resources/testharness.js"></script>
   5 <script src="/resources/testharnessreport.js"></script>
   6 <link rel="help" href="https://html.spec.whatwg.org/multipage/scripting.html#the-imagebitmap-rendering-context">
   7 <script>
   8 var width = 10;
   9 var height = 10;
  10
  11 function testCanvas(bitmapCanvas, r, g, b, a)
  12 {
  13     var myCanvas = document.createElement('canvas');
  14     myCanvas.width = width;
  15     myCanvas.height = height;
  16     var myCtx = myCanvas.getContext('2d');
  17     myCtx.drawImage(bitmapCanvas, 0, 0);
  18     var color = myCtx.getImageData(5, 5, 1, 1).data;
  19     assert_array_equals(color, [r, g, b, a]);
  20 }
  21
  22 promise_test(function() {
  23     function testTransferFromImageBitmapNullability(greenImage, redImage) {
  24         var bitmapCanvas = new OffscreenCanvas(width,height);
  25         var bitmapCtx = bitmapCanvas.getContext('bitmaprenderer');
  26         bitmapCtx.transferFromImageBitmap(greenImage);
  27
  28         // Make sure the bitmap renderer canvas is filled correctly.
  29         testCanvas(bitmapCanvas, 0, 255, 0, 255);
  30
  31         // Test if passing null resets the bitmap renderer canvas.
  32         // Drawing the resetted canvas cannot change the destination canvas.
  33         bitmapCtx.transferFromImageBitmap(null);
  34         testCanvas(bitmapCanvas, 0, 0, 0, 0);
  35
  36         // Test if we can redraw the bitmap canvas correctly after reset.
  37         bitmapCtx.transferFromImageBitmap(redImage);
  38         testCanvas(bitmapCanvas, 255, 0, 0, 255);
  39     }
  40
  41     var greenCanvas = document.createElement('canvas');
  42     greenCanvas.width = width;
  43     greenCanvas.height = height;
  44     var greenCtx = greenCanvas.getContext('2d');
  45     greenCtx.fillStyle = '#0f0';
  46     greenCtx.fillRect(0, 0, width, height);
  47
  48     var redCanvas = document.createElement('canvas');
  49     redCanvas.width = width;
  50     redCanvas.height = height;
  51     var redCtx = redCanvas.getContext('2d');
  52     redCtx.fillStyle = '#f00';
  53     redCtx.fillRect(0, 0, width, height);
  54
  55     return Promise.all([
  56         createImageBitmap(greenCanvas),
  57         createImageBitmap(redCanvas),
  58     ]).then(([greenImage, redImage]) => {
  59         testTransferFromImageBitmapNullability(greenImage, redImage);
  60     });
  61 },'Test that transferFromImageBitmap(null) discards the previously transferred image');
  62
  63 </script>