[webkit-changes] [WebKit/WebKit] caab01: [css-grid] Last baseline aligned grid items should...

[Sammy Gill]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: caab01d5e748531c1ff7fbcdab9b2da36801d73e
      https://github.com/WebKit/WebKit/commit/caab01d5e748531c1ff7fbcdab9b2da36801d73e
  Author: Sammy Gill <sammy.gill at apple.com>
  Date:   2023-09-12 (Tue, 12 Sep 2023)

  Changed paths:
    M LayoutTests/imported/w3c/web-platform-tests/css/css-grid/alignment/grid-align-baseline-001-expected.txt
    M LayoutTests/imported/w3c/web-platform-tests/css/css-grid/alignment/grid-align-baseline-002-expected.txt
    M LayoutTests/imported/w3c/web-platform-tests/css/css-grid/alignment/grid-justify-baseline-002-expected.txt
    M Source/WebCore/rendering/GridTrackSizingAlgorithm.cpp

  Log Message:
  -----------
  [css-grid] Last baseline aligned grid items should use the start of the last track they span for their alignment context
https://bugs.webkit.org/show_bug.cgi?id=261244
rdar://115083708

Reviewed by Matt Woodrow.

Instead of using span.endLine() for a last baseline aligned grid item's
alignment context, we should use span.endLine() - 1. This will allow
them to be in the same alignment context and potentially the same
baseline sharing group as first baseline aligned items in the same
track. For example, both items in the following grid should be in
the same baseline sharing group and should be aligned together as a
result:

<style>
  display: grid;
  grid-auto-flow: column;
  align-items: last baseline;
  width: 200px;
  writing-mode: vertical-lr;
}
  background: lime;
  margin-right: 20px;
  padding-right: 20px;
  font-size: 20px;
  line-height: 20px;
  align-self: first baseline;
  writing-mode: vertical-rl;
}
  background: hotpink;
  font-size: 30px;
  line-height: 30px;
  writing-mode: vertical-lr;
}
</style>
<div id="grid">
  <div>line1<br>line2</div>
  <div>line1<br>line2</div>
<div>

* LayoutTests/imported/w3c/web-platform-tests/css/css-grid/alignment/grid-align-baseline-001-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/css/css-grid/alignment/grid-align-baseline-002-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/css/css-grid/alignment/grid-justify-baseline-002-expected.txt:
* Source/WebCore/rendering/GridTrackSizingAlgorithm.cpp:
(WebCore::alignmentContextForBaselineAlignment):
(WebCore::GridTrackSizingAlgorithm::updateBaselineAlignmentContext):
(WebCore::GridTrackSizingAlgorithm::baselineOffsetForChild const):

Canonical link: https://commits.webkit.org/267922@main