test_media_queries_with_zoom.html

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<!DOCTYPE HTML>

<html>

<head>

  <title>Media Queries with Zoom</title>

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

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

</head>

<body>

<div>Testing media queries with different zoom levels</div>

<script type="application/javascript">

const originalDPR = window.devicePixelRatio;

const originalZoom = SpecialPowers.getFullZoom(window);

const zoomsToTest = [

300,

240,

200,

170,

150,

133,

120,

110,

100,

90,

80,

67,

50,

30,

];

for (let i = 0; i < zoomsToTest.length; ++i) {

  let zoomPercent = zoomsToTest[i];

  let relativeZoom = originalZoom * zoomPercent / 100;

  SpecialPowers.setFullZoom(window, relativeZoom);

  let actualZoom = SpecialPowers.getDeviceFullZoom(window);

  let targetDPR = (originalDPR * actualZoom);

  let actualDPR = window.devicePixelRatio;

  let mql = window.matchMedia(`(resolution: ${targetDPR}dppx)`);

  ok(mql.matches, `At ${zoomPercent}% zoom, target ${targetDPR}dppx matches ${actualDPR}dppx.`);

// Reset the zoom when the test is done.

SpecialPowers.setFullZoom(window, originalZoom);

</script>

</body>

</html>