| <!DOCTYPE html> |
| <meta name="viewport" content="width=device-width"> |
| <title> |
| Snap to points of combinations of two different elements |
| </title> |
| <link rel="help" href="https://drafts.csswg.org/css-scroll-snap-1/"/> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <style> |
| div { |
| position: absolute; |
| margin: 0px; |
| } |
| |
| #scroller { |
| height: 600px; |
| width: 600px; |
| overflow: hidden; |
| scroll-snap-type: both mandatory; |
| } |
| |
| #space { |
| width: 2000px; |
| height: 2000px; |
| } |
| |
| #left-top { |
| /* |
| * the scroll position of this `scroll-snap-align: start start` is (200, 200) |
| */ |
| left: 200px; |
| top: 200px; |
| height: 450px; |
| width: 450px; |
| background-color: rgb(255, 0, 0); |
| opacity: 0.5; |
| scroll-snap-align: start start; |
| } |
| |
| #right-bottom { |
| /* |
| * the scroll position of this `scroll-snap-align: end end` is (50, 250), |
| * i.e, (`left` - scroll container's `width` + this element's `width, |
| `top` - scroll container's `height` + this element's `height) |
| */ |
| left: 600px; |
| top: 800px; |
| width: 50px; |
| height: 50px; |
| background-color: rgb(0, 255, 0); |
| opacity: 0.5; |
| scroll-snap-align: end end; |
| } |
| |
| </style> |
| <div id="scroller"> |
| <div id="space"></div> |
| <div id="left-top"></div> |
| <div id="right-bottom"></div> |
| </div> |
| <script> |
| test(t => { |
| // There are four combinations of snap positions defined by #top-left and |
| // #right-bottom elements. |
| // (200, 200), (50, 250), (200, 250) and (50, 200). |
| // But snapping to (50, 200) leaves the snap area of #right-bottom element |
| // outside of the snapport, thus it won't be a valid snap position. |
| const scroller = document.getElementById("scroller"); |
| |
| // The nearest valid snap position from (0, 0) is (50, 250). |
| assert_equals(scroller.scrollLeft, 50); |
| assert_equals(scroller.scrollTop, 250); |
| |
| // (50, 200) is not valid, thus the nearest one from (100, 150) is (200, 200). |
| scroller.scrollTo(100, 150); |
| assert_equals(scroller.scrollLeft, 200); |
| assert_equals(scroller.scrollTop, 200); |
| |
| scroller.scrollTo(300, 300); |
| assert_equals(scroller.scrollLeft, 200); |
| assert_equals(scroller.scrollTop, 250); |
| |
| scroller.scrollTo(200, 100); |
| assert_equals(scroller.scrollLeft, 200); |
| assert_equals(scroller.scrollTop, 200); |
| }, 'Snap to points of combinations of two different elements'); |
| </script> |
