helper_zoom_restore_position_tabswitch.html

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<!DOCTYPE HTML>

<html>

<head>

  <meta charset="utf-8">

  <meta name="viewport" content="width=device-width">

  <title>Switching tabs back to a zoomed page should restore visual offset</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 src="/tests/SimpleTest/EventUtils.js"></script>

  <script type="application/javascript">

async function test() {

  let visResEvt = new EventCounter(window.visualViewport, "resize");

  // Do a pinch-zoom in, wait for everything to settle on the APZ side.

  await pinchZoomInWithTouch(400, 300);

  await promiseApzFlushedRepaints();

  // Force a new layer tree to the compositor, because otherwise tab-switching

  // away and back can end up reusing the last layer tree sent to the compositor,

  // and that may not have the latest visual viewport offset sent from APZ

  // to the main thread. This should be removed once bug 1640730 is fixed.

  await forceLayerTreeToCompositor();

  // Wait until we get a visual viewport resized event, if we haven't yet gotten

  // one.

  if (visResEvt.count == 0) {

    await promiseOneEvent(window.visualViewport, "resize", null);

  let resizeCount = visResEvt.count;

  ok(resizeCount > 0, `Visual viewport got resized ${resizeCount} times`);

  // Record the current visual viewport and ensure it reflects a zoomed state.

  let zoomedViewport = visualViewportAsZoomedRect();

  ok(visualViewport.offsetLeft > 0, "Visual viewport should not be same as layout viewport (left)");

  ok(visualViewport.offsetTop > 0, "Visual viewport should not be same as layout viewport (top)");

  ok(zoomedViewport.x > 0, "Sanity check to ensure visual viewport is not at 0,0 (left)");

  ok(zoomedViewport.y > 0, "Sanity check to ensure visual viewport is not at 0,0 (top)");

  ok(zoomedViewport.z > 1, "Sanity check to ensure visual viewport scale is > 1");

  // Open a new foreground tab and wait until it closes itself. The tab itself

  // waits for APZ stability before closing, so we know that the APZ state

  // was updated to the other document and back to this window.

  let focusPromise = promiseOneEvent(window, "focus", null);

  window.open("helper_self_closer.html", "_blank");

  await focusPromise;

  ok(true, "Got focus back after self-closer closed");

  // Wait for the dust to settle.

  await promiseApzFlushedRepaints();

  // Ensure the visual viewport is just as we left it.

  let restoredViewport = visualViewportAsZoomedRect();

  for (field in zoomedViewport) {

    is(restoredViewport[field], zoomedViewport[field], `Field ${field} of the zoomed viewport restored`);

  // Just for good measure. This might help with debugging unexpected failures.

  is(visResEvt.count, resizeCount, "No more VV resizes should have occurred");

waitUntilApzStable()

.then(test)

.then(subtestDone, subtestFailed);

  </script>

</head>

<body>

  Here is some text to stare at as the test runs. It serves no functional

  purpose, but gives you an idea of the zoom level. It's harder to tell what

  the zoom level is when the page is just solid white.

</body>

</html>