helper_reset_zoom_bug1818967.html

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<!DOCTYPE html>

<html lang="en"><head>

<meta http-equiv="content-type" content="text/html; charset=UTF-8">

<meta charset="utf-8">

<title>Test that we do not checkerboard after resetting the pinch-zoom scale</title>

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

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

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

<style>

.scrolled {

  width: 10000px;

  height: 10000px;

  background: linear-gradient(lime, cyan);

</style>

</head><body>

  <div class="scrolled"></div>

</body>

<script type="application/javascript">

async function test() {

  var utils = SpecialPowers.getDOMWindowUtils(window);

  var scrollerId = utils.getViewId(document.documentElement);

  // Zoom in to the maximum level

  utils.setResolutionAndScaleTo(10.0);

  await promiseApzFlushedRepaints();

  // Scroll the layout viewport to around middle of the page

  window.scrollTo(window.scrollMaxX / 2, window.scrollMaxY / 2);

  await promiseApzFlushedRepaints();

  // Scroll the visual viewport to the bottom of the layout viewport.

  // This creates an offset between the visual and layout viewport

  // offsets which is needed to trigger the bug.

  utils.scrollToVisual(window.scrollX,

                       window.scrollY + (0.9 * document.documentElement.clientHeight),

                       utils.UPDATE_TYPE_MAIN_THREAD,

                       utils.SCROLL_MODE_INSTANT);

  await promiseApzFlushedRepaints();

  // Reset the zoom level to 1.0x

  utils.setResolutionAndScaleTo(1.0);

  await promiseApzFlushedRepaints();

  // Assert that we're not checkerboarded

  assertNotCheckerboarded(utils, scrollerId, "After resetting zoom level");

waitUntilApzStable()

.then(test)

.then(subtestDone, subtestFailed);

</script>

</html>