Bug 269818 – REGRESSION(IFC multicol): Satisfying `widows` can cause a floating image to overlap text

• Status: RESOLVED
• Resolution: FIXED
• Component: Layout and Rendering

[Brad Andalman]

Created attachment 469992 [details]
HTML exhibiting the bug (text overlaps square)

In the attached HTML, I have a multi-column layout with a floating “image” that must be positioned at the top of the second column. (The image is partially transparent so it’s easy to see when it overlaps text.)

When `widows` is not set on the paragraph that spans these two columns, the text correctly wraps around the image. This results in two lines in the second column. However, when `widows` is set to 3, the entire last line in the first column now appears at the top of the second column, and intersects the floating image.

I’ll also attach screenshots that shows this HTML in Safari (incorrect), Chrome (correct), and Firefox (correct). I also tested in Safari 16.6, where it renders correctly.

Lastly, I checked in the latest WebKit build ([e-mail]) to see if it was fixed there already but, sadly, it was not.

[Brad Andalman]

Created attachment 469993 [details]
Rendered HTML showing the bug (text overlaps square)

[Brad Andalman]

Created attachment 469994 [details]
Screenshots of Chrome and Firefox correctly rendering this HTML (no text in the square)

[Radar WebKit Bug Importer]

<rdar://problem/123343009>

[zalan]

Created attachment 469995 [details]
Test reduction

[Brad Andalman]

Oh. That’s a much better test. Thanks!

And thanks, as always, for looking at this!

[zalan]

(In reply to Brad Andalman from comment #5)
> Oh. That’s a much better test. Thanks!
> 
> And thanks, as always, for looking at this!
np, your test reduction was pretty good already (I just prefer the least amount of inline content possible -to make debugging easier)

[zalan]

apparently when we move lines across columns due to widow/orphan constraints, we happily ignore intrusive floats (floats sticking out from previous block containers). I have to defer to @antti here (will talk to him about this)

[Antti Koivisto]

Pull request: https://github.com/WebKit/WebKit/pull/25285

[Brad Andalman]

Thanks so much for this fix, @antti!

[EWS]

Committed 275629@main (65ee365616b1): <https://commits.webkit.org/275629@main>

Reviewed commits have been landed. Closing PR #25285 and removing active labels.