| <!DOCTYPE html> |
| <title>Tests position fallback with bottom-up scroller</title> |
| <link rel="author" href="mailto:xiaochengh@chromium.org"> |
| <link rel="help" href="https://drafts.csswg.org/css-anchor-1/#scroll"> |
| <link rel="help" href="https://drafts.csswg.org/css-anchor-1/#fallback-apply"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <script src="support/test-common.js"></script> |
| |
| <style> |
| #containing-block { |
| width: 400px; |
| height: 400px; |
| transform: scale(1); |
| border: 1px solid black; |
| } |
| |
| #scroller { |
| display: flex; |
| flex-direction: column-reverse; |
| width: 400px; |
| height: 400px; |
| overflow-y: scroll; |
| } |
| |
| .box { |
| min-height: 100px; |
| width: 100px; |
| } |
| |
| #anchor { |
| anchor-name: --a; |
| background: orange; |
| } |
| |
| #anchored { |
| position: absolute; |
| top: anchor(bottom); |
| width: 100px; |
| height: 100px; |
| background: green; |
| position-anchor: --a; |
| position-try-fallbacks: --pf; |
| } |
| |
| @position-try --pf { |
| top: auto; |
| bottom: anchor(top); |
| } |
| </style> |
| |
| <div id="containing-block"> |
| <div id="scroller"> |
| <div class="box"></div> |
| <div class="box" id="anchor"></div> |
| <div class="box"></div> |
| <div class="box"></div> |
| <div class="box"></div> |
| </div> |
| <div id="anchored"></div> |
| </div> |
| |
| <script> |
| promise_test(async () => { |
| await waitUntilNextAnimationFrame(); |
| assert_fallback_position(anchored, anchor, 'bottom'); |
| }, 'Should use the first fallback position at the initial scroll offset'); |
| |
| promise_test(async () => { |
| scroller.scrollTop = -1; |
| await waitUntilNextAnimationFrame(); |
| assert_fallback_position(anchored, anchor, 'top'); |
| }, 'Should use the second fallback position after scrolling up'); |
| </script> |
