Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 524261aa11f89debe31be4643e2704016b079c8a
https://github.com/WebKit/WebKit/commit/524261aa11f89debe31be4643e2704016b079c8a
Author: Ahmad Saleem <[email protected]>
Date: 2026-10-05 (Mon, 05 Oct 2026)
Changed paths:
A LayoutTests/fast/multicol/block-axis-columns-after-spanner-expected.html
A LayoutTests/fast/multicol/block-axis-columns-after-spanner.html
M Source/WebCore/rendering/RenderMultiColumnSet.cpp
Log Message:
-----------
[Multicol] Block-axis columns are painted at the wrong offset when the column
set does not start at the top of the multicol container
https://bugs.webkit.org/show_bug.cgi?id=326181
rdar://189067503
Reviewed by Antti Koivisto.
In RenderMultiColumnSet::collectLayerFragments(), the block offset for
forward block-axis progression (e.g. `-webkit-column-axis: vertical`, or
TopToBottom pagination) was assigned `i * colGap`, which discards the base
offset computed just above it (the set's position relative to the flow
thread and the column's flow-thread portion). This only gave the right
result when that base offset happened to be zero, i.e. a single column set
starting at the top of the flow thread.
When a column set follows a `column-span: all` spanner, the columns were
painted shifted up by the spanner's height, on top of the spanner, while
layout and getClientRects() reported the correct position.
Add the column's full block-axis advance instead, mirroring the reversed
progression branch.
Test: fast/multicol/block-axis-columns-after-spanner.html
* LayoutTests/fast/multicol/block-axis-columns-after-spanner-expected.html:
Added.
* LayoutTests/fast/multicol/block-axis-columns-after-spanner.html: Added.
* Source/WebCore/rendering/RenderMultiColumnSet.cpp:
(WebCore::RenderMultiColumnSet::collectLayerFragments const):
Canonical link: https://commits.webkit.org/322687@main
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