gfx/tests/reftest/1972885-ref.html

   1 <!DOCTYPE html>
   2 <html>
   3 <meta charset="utf-8">
   4 <title>Reference for Bug 1972885</title>
   5 <style>
   6 body {
   7   margin: 0;
   8 }
   9 canvas {
  10   /* Rounded up. */
  11   margin-top: 2px;
  12   width: 100px;
  13   /* Subpixel snapped down. */
  14   height: 100px;
  15 }
  16 </style>
  17 <canvas id="canvas"></canvas>
  18 <script>
  19 function draw(canvas, width, height) {
  20   const ctx = canvas.getContext('2d');
  21   canvas.width = width;
  22   canvas.height = height;
  23   const imgData = ctx.createImageData(width, height);
  24   const u32View = new Uint32Array(imgData.data.buffer);
  25   u32View.fill(0xFFFFFFFF);
  26   for (let y = 0; y < height; y += 2) {
  27     for (let x = 0; x < width; x++) {
  28       u32View[y * width + x] = 0xFF000000;
  29     }
  30   }
  31   ctx.putImageData(imgData, 0, 0);
  32 }
  33
  34 draw(canvas, 100, 100);
  35 </script>