| <!DOCTYPE html> |
| <html> |
| |
| <head> |
| <link rel="help" href="https://drafts.csswg.org/css-scroll-snap-1/#scroll-snap-type" /> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <script src="/resources/testdriver.js"></script> |
| <script src="/resources/testdriver-actions.js"></script> |
| <script src="/resources/testdriver-vendor.js"></script> |
| <script src="/dom/events/scrolling/scroll_support.js"></script> |
| </head> |
| <body> |
| <style> |
| #scroller { |
| overflow: scroll; |
| scroll-snap-type: y mandatory; |
| height: 200px; |
| width: 200px; |
| border: solid 1px; |
| position:absolute; |
| } |
| .snap_area { |
| position: absolute; |
| width: 100px; |
| left: calc(50% - 50px); |
| } |
| #outer_snap_area { |
| scroll-snap-align: start; |
| height: 1000px; |
| background-color: blue; |
| } |
| #inner_snap_area { |
| scroll-snap-align: start; |
| height: 100px; |
| top: 100px; |
| background-color: yellow; |
| } |
| </style> |
| <div id="scroller"> |
| <div id="outer_snap_area" class="snap_area"></div> |
| <div id="inner_snap_area" class="snap_area"></div> |
| </div> |
| <script> |
| async function reset() { |
| inner_snap_area.style.height = "100px"; |
| await waitForCompositorCommit(); |
| } |
| |
| let scroller = document.getElementById("scroller"); |
| promise_test(async (t) => { |
| await reset(); |
| await resetTargetScrollState(t, scroller); |
| assert_equals(scroller.scrollTop, 0, "test precondition: scroller is " + |
| "not scrolled"); |
| let scrollend_promise = waitForScrollendEventNoTimeout(scroller); |
| let target_snap_position = inner_snap_area.offsetTop + |
| inner_snap_area.offsetHeight; |
| // Scroll to an offset close to the bottom of the inner snap area and |
| // expect to snap to an offset just below this snap area. |
| scroller.scrollTo(0, target_snap_position - 10); |
| await scrollend_promise; |
| assert_equals(scroller.scrollTop, target_snap_position, |
| "scroller snaps to just below the inner snap area."); |
| // We are just below the inner snap area. Increase its height so that it |
| // is larger than the snapport and straddled by the snapport. Verify |
| // that we snap to its bottom. |
| inner_snap_area.style.height = |
| `${scroller.clientHeight + inner_snap_area.clientHeight - 10}px`; |
| await waitForCompositorCommit(); |
| target_snap_position = inner_snap_area.offsetTop + |
| inner_snap_area.offsetHeight - scroller.clientHeight; |
| assert_equals(scroller.scrollTop, target_snap_position, |
| "scroller snaps to the bottom of the smaller snap area (which is now " + |
| "covering)."); |
| }, "newly larger-than-snapport area is snapped to when straddled close " + |
| "to bottom."); |
| |
| promise_test(async (t) => { |
| await reset(); |
| await resetTargetScrollState(t, scroller); |
| assert_equals(scroller.scrollTop, 0, "test precondition: scroller is " + |
| "not scrolled"); |
| let scrollend_promise = waitForScrollendEventNoTimeout(scroller); |
| let target_snap_position = inner_snap_area.offsetTop + |
| inner_snap_area.offsetHeight; |
| // Scroll to an offset close to the bottom of the inner snap area and |
| // expect to snap to an offset just below this snap area. |
| scroller.scrollTo(0, target_snap_position - 10); |
| await scrollend_promise; |
| assert_equals(scroller.scrollTop, target_snap_position, |
| "scroller snaps to just below the inner snap area."); |
| // We are just below the inner snap area. Increase its height so that it |
| // is larger than the snapport and covers the snapport. Verify that we |
| // remain in the covering position. |
| inner_snap_area.style.height = |
| `${scroller.clientHeight + inner_snap_area.clientHeight + 10}px`; |
| await waitForCompositorCommit(); |
| assert_equals(scroller.scrollTop, target_snap_position, |
| "scroller snaps to the bottom of the smaller snap area (which is now " + |
| "covering)."); |
| }, "snapport remains within newly covering snap area when already in " + |
| "covering position."); |
| </script> |
| </body> |
