| <!DOCTYPE html> |
| <link rel="help" href="https://drafts.csswg.org/css-scroll-snap-1/#scroll-margin" /> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <style> |
| div { |
| position: absolute; |
| margin: 0px; |
| } |
| #scroller { |
| height: 500px; |
| width: 500px; |
| overflow: hidden; |
| scroll-snap-type: both mandatory; |
| } |
| #target { |
| width: 300px; |
| height: 300px; |
| background-color: blue; |
| } |
| #another-target { |
| width: 300px; |
| height: 300px; |
| top: 400px; |
| left: 400px; |
| background-color: blue; |
| scroll-snap-align: start; |
| } |
| </style> |
| |
| <div id="scroller"> |
| <div style="width: 2000px; height: 2000px;"></div> |
| <div id="target"></div> |
| <div id="another-target"></div> |
| </div> |
| |
| <script> |
| test(() => { |
| target.style.scrollSnapAlign = "start"; |
| target.style.scrollMargin = "100px"; |
| target.style.left = "300px"; |
| target.style.top = "300px"; |
| |
| scroller.scrollTo(0, 0); |
| // `target position (300px, 300px)` - `margin (100px, 100px)`. |
| assert_equals(scroller.scrollLeft, 200); |
| assert_equals(scroller.scrollTop, 200); |
| |
| target.style.scrollSnapAlign = "end"; |
| |
| // `target position (300px, 300px)` + `target size (300px, 300px) + |
| // `margin (100px, 100px) - `scroller size (500px, 500px)`. |
| scroller.scrollTo(0, 0); |
| assert_equals(scroller.scrollLeft, 200); |
| assert_equals(scroller.scrollTop, 200); |
| }, "Snaps to the positions adjusted by scroll-margin"); |
| |
| test(() => { |
| target.style.left = "0px"; |
| target.style.top = "0px"; |
| |
| target.style.scrollSnapAlign = "start"; |
| target.style.scrollMargin = "100px"; |
| |
| // Scroll to the position between #target and #another-target elements but |
| // if the scroll-margin 100px contributed to the snap start-aligned snap |
| // position it will be farther than #another-target. |
| scroller.scrollTo(200, 200); |
| assert_equals(scroller.scrollLeft, 0); |
| assert_equals(scroller.scrollTop, 0); |
| }, "scroll-margin doesn't contribute to the snap position of the element " + |
| "if it's outside of the scroll port"); |
| </script> |
