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<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>Test for bug 1562757: "scroll into view" in iframe 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>
#iframe {
width: 100px;
height: 100px;
margin-left: 50%;
margin-right: 50%;
background: cyan;
display: block;
<iframe id="iframe" scrolling="no" frameborder="no" srcdoc="<div id='target' style='width:100px;height:100px;'></div>"></iframe>
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 = iframe.contentDocument.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 });
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 = iframe.getBoundingClientRect();
assertRectContainment(vvRect, "visual viewport", targetBounds, "iframe having the target element bounding rect");
.then(subtestDone, subtestFailed);