helper_scroll_into_view_bug1516056.html

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<!DOCTYPE HTML>

<html>

<head>

  <meta charset="utf-8">

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

  <title>Test for bug 1516056: "scroll into view" respects bounds on layout scroll position</title>

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

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

  <style>

    #target {

      width: 100px;

      height: 100px;

      margin-left: 50%;

      margin-right: 50%;

      background: cyan;

  </style>

</head>

<body>

  <div id="target"></div>

  <script>

    let vv = window.visualViewport;

    function getVisualScrollRange() {

      let rootScroller = document.scrollingElement;

      return {

        width: rootScroller.scrollWidth - vv.width,

        height: rootScroller.scrollHeight - vv.height,

};

    async function test() {

      is(window.scrollMaxX, 0, "page should have a zero horizontal layout scroll range");

      is(window.scrollMaxY, 0, "page should have a zero vertical layout scroll range");

      let visualScrollRange = getVisualScrollRange();

      ok(visualScrollRange.width > 0, "page should have a nonzero horizontal visual scroll range");

      ok(visualScrollRange.height > 0, "page should have a nonzero vertical visual scroll range");

      let target = document.getElementById("target");

      // Scroll target element into view. Wait until any visual scrolling is done before doing checks.

      let scrollPromise = new Promise(resolve => {

        vv.addEventListener("scroll", resolve, { once: true });

});

      target.scrollIntoView();

      await scrollPromise; // wait for visual viewport "scroll" event

      await promiseApzFlushedRepaints();

      // Test that scrollIntoView() respected the layout scroll range.

      is(window.scrollX, 0, "page should not layout-scroll with a zero layout scroll range");

      is(window.scrollY, 0, "page should not layout-scroll with a zero layout scroll range");

      // Test that scrollIntoView() did perform visual scrolling.

      let vvRect = getVisualViewportRect(vv);

      let targetBounds = target.getBoundingClientRect();

      assertRectContainment(vvRect, "visual viewport", targetBounds, "target element bounding rect");

    SpecialPowers.getDOMWindowUtils(window).setResolutionAndScaleTo(2.0);

    waitUntilApzStable()

    .then(test)

    .then(subtestDone, subtestFailed);

  </script>

</body>

</html>