move-current-target.html | Explore in Territory

<!DOCTYPE html>
<title>
  Moving the current snap target should make the scroller resnap to it.
</title>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap/#re-snap" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
div {
  position: relative;
  margin: 0;
}

#block {
  height: 100px;
  width: 100px;
}

#scroller {
  height: 500px;
  width: 500px;
  overflow: hidden;
  scroll-snap-type: both mandatory;
}

#initial-target {
  width: 300px;
  height: 300px;
  left: 100px;
  top: 0;
  transform: none;
  background-color: green;
  scroll-snap-align: start;
}

#other-target {
  width: 300px;
  height: 300px;
  left: 300px;
  background-color: red;
  scroll-snap-align: start;
}

.area {
  width: 2000px;
  height: 2000px;
}
</style>

<div id="scroller">
  <div id="block"></div>
  <div id="initial-target"></div>
  <div id="other-target"></div>
  <div class="area"></div>
</div>

<script>
const initial_target = document.getElementById("initial-target");
const other_target = document.getElementById("other-target");
const block = document.getElementById("block");
const scroller = document.getElementById("scroller");

function cleanup() {
  initial_target.style.setProperty("transform", "none");
  initial_target.style.setProperty("top", "0");
  block.style.setProperty("height", "100px");
}

test(t => {
  t.add_cleanup(cleanup);
  scroller.scrollTo(0,0);
  assert_equals(scroller.scrollTop, 100);
  assert_equals(scroller.scrollLeft, 100);

  initial_target.style.setProperty("top", "300px");
  assert_equals(scroller.scrollTop, 400);
  assert_equals(scroller.scrollLeft, 100);
}, "Moving the current snap target should make the scroller resnap to it.");

test(t => {
  t.add_cleanup(cleanup);
  scroller.scrollTo(0,0);
  assert_equals(scroller.scrollTop, 100);
  assert_equals(scroller.scrollLeft, 100);

  block.style.setProperty("height", "200px");
  assert_equals(scroller.scrollTop, 200);
  assert_equals(scroller.scrollLeft, 100);
}, "Changing the layout of other elements should be able to cause resnapping to \
the target.");

test(t => {
  t.add_cleanup(cleanup);
  scroller.scrollTo(0,0);
  assert_equals(scroller.scrollTop, 100);
  assert_equals(scroller.scrollLeft, 100);

  initial_target.style.setProperty("transform", "translate(0,100px)");
  assert_equals(scroller.scrollTop, 200);
  assert_equals(scroller.scrollLeft, 100);
}, "Transforming the current snap target should make the scroller resnap to it.");

test(t => {
  t.add_cleanup(cleanup);
  initial_target.style.setProperty("top", "100px");
  scroller.scrollTo(0,0);
  assert_equals(scroller.scrollTop, 200);
  assert_equals(scroller.scrollLeft, 100);

  initial_target.style.setProperty("transform", "translate(0,100px)");
  initial_target.style.setProperty("top", "0");
  assert_equals(scroller.scrollTop, 200);
  assert_equals(scroller.scrollLeft, 100);
}, "Applying two property changes that do not change the visual offset of the \
target should not change the scroll offset.");
</script>
chromium/third_party/blink/web_tests/external/wpt/css/css-scroll-snap/snap-after-relayout/move-current-target.html
