| <!DOCTYPE html> |
| <title> |
| Updating the snap alignment of a snap container's content should make the snap |
| container resnap accordingly. |
| </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: absolute; |
| margin: 0; |
| } |
| |
| #scroller { |
| height: 200px; |
| width: 200px; |
| overflow: hidden; |
| scroll-snap-type: both mandatory; |
| } |
| |
| #initial-target { |
| width: 300px; |
| height: 300px; |
| top: 100px; |
| left: 100px; |
| background-color: green; |
| scroll-snap-align: start; |
| } |
| |
| #other-target { |
| width: 300px; |
| height: 300px; |
| top: 300px; |
| left: 300px; |
| background-color: red; |
| scroll-snap-align: start; |
| } |
| |
| .area { |
| width: 2000px; |
| height: 2000px; |
| } |
| |
| .snap-area { |
| scroll-snap-align: start !important; |
| } |
| </style> |
| |
| <div id="scroller"> |
| <div class="area"></div> |
| <div id="initial-target"></div> |
| <div id="other-target"></div> |
| </div> |
| |
| <script> |
| const initial_target = document.getElementById("initial-target"); |
| const other_target = document.getElementById("other-target"); |
| const scroller = document.getElementById("scroller"); |
| |
| function cleanup() { |
| initial_target.style.setProperty("scroll-snap-align", "start"); |
| other_target.style.setProperty("scroll-snap-align", "start"); |
| initial_target.removeAttribute("class"); |
| } |
| |
| test(t => { |
| t.add_cleanup(cleanup); |
| scroller.scrollTo(0,0); |
| assert_equals(scroller.scrollTop, 100); |
| assert_equals(scroller.scrollLeft, 100); |
| |
| initial_target.style.setProperty("scroll-snap-align", "end"); |
| // scroller maintains scroll position which is still valid as the target's |
| // snap area covers the snap port. |
| assert_equals(scroller.scrollTop, 100); |
| assert_equals(scroller.scrollLeft, 100); |
| }, "Changing a large target's snap alignment shouldn't make the scroller" + |
| " resnap if the scroller is already in a valid snap position."); |
| |
| // Similar to above test case except targets are too small to cover snap port, |
| // so scroller must snap in response to change in scroll-snap-align. |
| test(t => { |
| t.add_cleanup(cleanup); |
| const initial_target_height = initial_target.offsetHeight; |
| const initial_target_width = initial_target.offsetWidth; |
| const other_target_height = initial_target.offsetHeight; |
| const other_target_width = initial_target.offsetWidth; |
| t.add_cleanup(() => { |
| initial_target.style.setProperty("height", `${initial_target_height}px`); |
| initial_target.style.setProperty("width", `${initial_target_width}px`); |
| other_target.style.setProperty("height", `${other_target_height}px`); |
| other_target.style.setProperty("width", `${other_target_width}px`); |
| }) |
| scroller.scrollTo(0,0); |
| assert_equals(scroller.scrollTop, 100); |
| assert_equals(scroller.scrollLeft, 100); |
| |
| initial_target.style.setProperty("height", `${scroller.clientHeight * 2/3 }px`); |
| initial_target.style.setProperty("width", `${scroller.clientWidth * 2/3 }px`); |
| other_target.style.setProperty("height", `${scroller.clientHeight * 2/3 }px`); |
| other_target.style.setProperty("width", `${scroller.clientWidth * 2/3 }px`); |
| |
| // scroll (and snap) to top left of other target. |
| scroller.scrollTo(other_target.offsetTop, |
| other_target.offsetLeft); |
| assert_equals(scroller.scrollTop, other_target.offsetTop,); |
| assert_equals(scroller.scrollLeft, other_target.offsetLeft); |
| |
| other_target.style.setProperty("scroll-snap-align", "end"); |
| // should be scrolled so as to align scroller's bottom-right with |
| // other_target's bottom-right. |
| assert_equals(scroller.scrollTop, |
| other_target.offsetTop + other_target.offsetHeight - scroller.clientHeight); |
| assert_equals(scroller.scrollLeft, |
| other_target.offsetLeft + other_target.offsetWidth - scroller.clientWidth); |
| }, "Changing the current (non-covering) target's snap alignment should make " + |
| "the scroller snap according to the new alignment."); |
| |
| test(t => { |
| t.add_cleanup(cleanup); |
| scroller.scrollTo(0,0); |
| assert_equals(scroller.scrollTop, 100); |
| assert_equals(scroller.scrollLeft, 100); |
| |
| initial_target.style.setProperty("scroll-snap-align", "none"); |
| assert_equals(scroller.scrollTop, 300); |
| assert_equals(scroller.scrollLeft, 300); |
| }, "Removing the current target's snap alignment should make the scroller" |
| + " resnap to a new snap area."); |
| |
| test(t => { |
| t.add_cleanup(cleanup); |
| initial_target.style.setProperty("scroll-snap-align", "none"); |
| other_target.style.setProperty("scroll-snap-align", "none"); |
| |
| scroller.scrollTo(0,0); |
| assert_equals(scroller.scrollTop, 0); |
| assert_equals(scroller.scrollLeft, 0); |
| |
| initial_target.style.setProperty("scroll-snap-align", "start"); |
| assert_equals(scroller.scrollTop, 100); |
| assert_equals(scroller.scrollLeft, 100); |
| }, "Changing an element snap alignment from none to start should make the" |
| + "scroller resnap."); |
| |
| test(t => { |
| t.add_cleanup(cleanup); |
| initial_target.style.setProperty("scroll-snap-align", "none"); |
| other_target.style.setProperty("scroll-snap-align", "none"); |
| |
| scroller.scrollTo(0,0); |
| assert_equals(scroller.scrollTop, 0); |
| assert_equals(scroller.scrollLeft, 0); |
| |
| initial_target.classList.add("snap-area"); |
| assert_equals(scroller.scrollTop, 100); |
| assert_equals(scroller.scrollLeft, 100); |
| }, "Changing an element snap alignment from none to start by adding a class" |
| + " should make the scroller resnap."); |
| </script> |