helper_doubletap_zoom_horizontal_center.html

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<!DOCTYPE HTML>

<html>

<head>

  <meta charset="utf-8">

  <meta name="viewport" content="width=2100"/>

  <title>Check that double tapping an element that doesn't fill the width of the viewport as maximum zoom centers it</title>

  <script type="application/javascript" src="apz_test_native_event_utils.js"></script>

  <script type="application/javascript" src="apz_test_utils.js"></script>

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

  <script type="application/javascript">

async function test() {

  let useTouchpad = (location.search == "?touchpad");

  var resolution = await getResolution();

  ok(resolution > 0,

     "The initial_resolution is " + resolution + ", which is some sane value");

  // Check that double-tapping once zooms in

  await doubleTapOn(document.getElementById("target"), 10, 10, useTouchpad);

  var prev_resolution = resolution;

  resolution = await getResolution();

  ok(resolution > 2*prev_resolution, "The first double-tap has increased the resolution to " + resolution);

  info("window.innerWidth " + window.innerWidth); // value when writing this test: 1280

  info("visualViewport.offsetLeft " + visualViewport.offsetLeft); //value when writing this test: 625 with bug, 537 with fix

  info("visualViewport.width " + visualViewport.width); // value when writing this test: 253

  // the left hand edge of the div is at window.innerWidth/2

  // we want approximately half of the visual viewport width to be to the left of that point.

  // we have to remove the 50 pixels for the width of the div from that first though.

  // we multiply that by 80% to factor in the 15 pixel margin we give the zoomed-to element

  // (we don't hard code 15 though since we might want to tweak that)

  ok(visualViewport.offsetLeft < window.innerWidth/2 - 0.8*(visualViewport.width-50)/2, "moved over far enough");

  // and then have a sanity check that it's not too small.

  // using the same 20% factor as before but in the other direction.

  ok(visualViewport.offsetLeft > window.innerWidth/2 - 1.2*(visualViewport.width-50)/2, "but not too far");

waitUntilApzStable()

.then(test)

.then(subtestDone, subtestFailed);

  </script>

</head>

<body>

<div id="target" style="background: blue; width: 50px; height: 50px; position: absolute; left: 50vw;"></div>

</body>

</html>