helper_scrollby_zoomed_bug1965670.html

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<!DOCTYPE HTML>

<html>

<head>

  <meta charset="utf-8">

  <meta name="viewport" content="width=device-width; initial-scale=1.0">

  <title>Test that scrollBy() works correctly when zoomed in</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">

    let utils = SpecialPowers.getDOMWindowUtils(window);

    async function test() {

      // Scroll the visual viewport within the layout viewport.

      utils.scrollToVisual(0, 100, utils.UPDATE_TYPE_MAIN_THREAD,

        utils.SCROLL_MODE_INSTANT);

      await promiseApzFlushedRepaints();

      is(window.scrollX, 0, "Layout viewport should be at (0, 0)");

      is(window.scrollY, 0, "Layout viewport should be at (0, 0)");

      is(visualViewport.pageLeft, 0, "Visual viewport should be at (0, 100)");

      is(visualViewport.pageTop, 100, "Visual viewport should be at (0, 100)");

      // Do a smooth scrollBy() in this state and wait for it

      // to complete.

      let scrollendPromise = promiseScrollend();

      window.scrollBy({ top: 40, left: 0, behavior: 'smooth' });

      await scrollendPromise;

      // Check that it's the layout viewport that scrolled.

      // The relative offset between the layout and visual viewports

      // should be preserved.

      is(window.scrollX, 0, "Layout viewport should be at (0, 0)");

      is(window.scrollY, 40, "Layout viewport should be at (0, 40)");

      is(visualViewport.pageLeft, 0, "Visual viewport should be at (0, 100)");

      is(visualViewport.pageTop, 140, "Visual viewport should be at (0, 140)");

    // Zoom in to create room to scroll the visual viewport within the

    // layout viewport.

    utils.setResolutionAndScaleTo(2.0);

    waitUntilApzStable()

      .then(test)

      .then(subtestDone, subtestFailed);

  </script>

  <style>

    body {

      height: 500vh;

      background: linear-gradient(red, black);

  </style>

</head>

<body>

</body>

</html>