Intent to Implement: visibility:collapse for table rows

[David Grogan]

Contact emails joy...@google.com,dgrogan@chromium.org Spec https://drafts.csswg.org/css-tables-3/#visible-track Summary visibility:collapse is supposed to hide table rows while preserving their contribution to column widths. Right now Blink treats visibility:collapse as visibility:hidden, which merely skips painting the rows, leaving blank space instead of allowing the space to be used for other content. Motivation

This property allows developers to hide rows in a non-visually-jarring manner. Without this change developers can use display:none, but switching between display:table-row and display:none can cause column widths to change, causing a jarring effect as column widths change and affected cells are re-laid out. Interoperability risk Firefox: Shipped Edge: Shipped Safari: Mixed public signals (patch posted in 2007 but no movement since) Web developers: Positive

Edge and Firefox are interoperable for the common case but differ when rowspan cells are affected. See https://bugs.chromium.org/p/chromium/issues/detail?id=174167#c35 for examples. Edge implements the CSS2.1 behavior. That's what we'll strive for as well, returning to the csswg if implementation turns out to be too hard. Compatibility risk Some sites may be using visibility:collapse when they really want visibility:hidden, relying on the fact that Blink and WebKit render them the same. But these sites would render differently in Edge and FF, so this would mostly affect WebKit/Blink-only sites. If the new behavior is unwanted, the fix is simple: change "visibility:collapse" to "visibility:hidden", which is what they meant from the start.

Ongoing technical constraints None Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)? Yes or no. Yes OWP launch tracking bug None yet - the technical bug is https://crbug.com/174167 Link to entry on the Chrome Platform Status https://www.chromestatus.com/features/5684392546533376 Requesting approval to ship? No

[PhistucK]

Can you search the internal index (or whatever) for websites that use this where implementing this would affect their rendering?

Is it possible to use-count it in advance?

☆PhistucK

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[Joy Yu]

Hi! I did a basic usage study and it seems like most websites use visibility:collapse on non-table elements, so correctly implementing visibility:collapse for tables shouldn't have much negative effect :)

To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CABc02_K3Hzdi2CpjgFnhp9z36tKX84C-y7%2Bw7s0aOg2noFrKEg%40mail.gmail.com.

[PhistucK]

HTTPArchive only includes homepages of website. Homepages are not likely to have tables, so I would not exactly call it a representative corpus for this feature. :(

☆PhistucK

[Joy Yu]

Hi! I updated the Google doc and updated the results with a Github search. In short, I found some cases of visibility:collapse applied on row/row groups, but they were mostly Firefox tests since Firefox supports visibility:collapse. Please let me know if you have any more questions or a better way to do a usage search! Thanks so much :)