test_bug1803209.html

Enable keyboard shortcuts

<!DOCTYPE HTML>

<html>

<head>

  <script src="/tests/SimpleTest/SimpleTest.js"></script>

  <script src="/tests/SimpleTest/EventUtils.js"></script>

  <link rel="stylesheet" href="/tests/SimpleTest/test.css"/>

</head>

<body>

<style>

.box {

    background: linear-gradient(90deg, rgba(256,0,0,1), rgba(256,0,0,1));

    background-attachment: fixed;

    width: 25%;

    height: 450px;

</style>

<div style="height: 1000vh;"></div>

<div class="box"></div>

<script>

SimpleTest.waitForExplicitFinish();

add_task(async function() {

  let utils = SpecialPowers.DOMWindowUtils;

  let sc = document.getElementById("sc");

  let boundingClientRect = document.documentElement.getBoundingClientRect();

  let canvas = document.createElement("canvas");

  canvas.setAttribute("width", boundingClientRect.width);

  canvas.setAttribute("height", boundingClientRect.height);

  let ctx = canvas.getContext("2d");

  let rect = new window.DOMRect(boundingClientRect.x, boundingClientRect.y,

                 boundingClientRect.width,

                 boundingClientRect.height);

  let image = await SpecialPowers.snapshotContext(window, rect, "rgb(255,255,255)");

  SpecialPowers.wrap(ctx).drawImage(image, 0, 0);

  var data = ctx.getImageData(0, 0, boundingClientRect.width, boundingClientRect.height).data;

  var foundRed = false;

  for (var i = 0; i < data.length; i+=4) {

    if (data[i] == 255 && data[i+1] == 0 && data[i+2] == 0 && data[i+3] == 255) {

      foundRed = true;

      break;

  ok(foundRed, "found some red pixels");

});

</script>

</body>

</html>