Intent to Remove: overflow: -webkit-paged-x , overflow: -webkit-paged-y

Ian Kilpatrick

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Mar 11, 2019, 5:54:40 PM3/11/19

to blink-dev

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Summary

This is an old webkit specific feature that allowed developers to fragment content over columns, inside a scrollable region.

See: https://bl.ocks.org/grorg/99eb053b432070b05d1e29759d81458f

Practically speaking this isn't used for this. Most developers use it accidentally, typically when to force a new formatting context. Similar to setting "overflow: hidden".

Motivation

For developers who wish to have fragmented content, a more standardized way to do this is with multi-column: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Columns

See the previous example using this technique: https://jsbin.com/vovelabewe/edit?html,output

For developers wishing to establish a new formatting context (to prevent margin-collapsing or similar), display: flow-root, or overflow: hidden both work. This feature isn't widely used, and maintaining it indefinitely will likely result it a maintenance burden.

Interoperability and Compatibility Risks:

The compat risk here is small. I placed a UseCounter for this feature in our codebase a while ago:

https://www.chromestatus.com/metrics/feature/timeline/popularity/1867

I sampled 50 of the websites which used this feature based on the above use-counter:

https://docs.google.com/spreadsheets/d/14w1IoSzW-ZU86U-o6j4VkCugnj_fNxQKNO_x5TEwvPk/edit?usp=sharing

The majority of sites didn't have any effect when I removed the rule. Of those that did have changes they were:

- Positioning changes of <1em was the primary difference (due to different margin-collapsing logic typically), no content ended up overlapping.

- One had a somewhat bad visual change due to height (due to margins) being calculated differently.

I found no sites that were using this feature for what it was intended for.

I believe if we leave this feature in Blink, it will create compatibility issues for other renderers in the future.

Firefox: No public signals

Edge: No public signals

Safari: Shipped

Is this feature fully tested by web-platform-tests?

No

Link to entry on the Chrome Platform Status

https://www.chromestatus.com/features/5731653806718976

flo...@rivoal.net

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Mar 11, 2019, 7:58:54 PM3/11/19

to blink-dev

+1

We should do this cleanly at some point (and I hope to introduce something along these lines sometimes later this year). Until then, this is a bit of a hack, and removing it makes sense.

—Florian

PS: I follow these intents in twitter. It'd be nice if there was a way to respond to the tweets and have the comments made there come back into this thread https://twitter.com/frivoal/status/1105241405704724480 :)

Chris Harrelson

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Mar 11, 2019, 8:35:11 PM3/11/19

to flo...@rivoal.net, blink-dev

LGTM1

Please also file a WebKit bug asking for removal, w/data.

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Morten Stenshorne

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Mar 12, 2019, 5:37:33 AM3/12/19

to Ian Kilpatrick, blink-dev

It would be great to have a more primitive way of doing fragmentation
than being forced to use columns. Paged overflow provides this in a way,
but it's not standardized, and this has been the situation for
years. The implementation also does strange things, such as honoring
column-gap. Getting rid of the whole thing solves that problem. :)

Code-owner (but otherwise non-owner) LGTM for removal.

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Morten Stenshorne, Software developer,
Blink/Layout, Google, Oslo, Norway

Ojan Vafai

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Mar 12, 2019, 2:12:07 PM3/12/19

to Morten Stenshorne, Ian Kilpatrick, blink-dev

lgtm2

Morten Stenshorne wrote:

It would be great to have a more primitive way of doing fragmentation than being forced to use columns. Paged overflow provides this in a way, but it's not standardized, and this has been the situation for years. The implementation also does strange things, such as honoring column-gap. Getting rid of the whole thing solves that problem. :) Code-owner (but otherwise non-owner) LGTM for removal. Ian Kilpatrick writes: > Contact emails > ikilp...@chromium.org > > Summary > This is an old webkit specific feature that allowed developers to fragment content over columns, inside a scrollable > region. > > See: https://bl.ocks.org/grorg/99eb053b432070b05d1e29759d81458f > > Practically speaking this isn't used for this. Most developers use it accidentally, typically when to force a new > formatting context. Similar to setting "overflow: hidden". > > Motivation > For developers who wish to have fragmented content, a more standardized way to do this is with multi-column: > https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Columns > > See the previous example using this technique: https://jsbin.com/vovelabewe/edit?html,output > > For developers wishing to establish a new formatting context (to prevent margin-collapsing or similar), display: > flow-root, or overflow: hidden both work. This feature isn't widely used, and maintaining it indefinitely will likely result > it a maintenance burden. > > Interoperability and Compatibility Risks: > The compat risk here is small. I placed a UseCounter for this feature in our codebase a while ago: > https://www.chromestatus.com/metrics/feature/timeline/popularity/1867 > > I sampled 50 of the websites which used this feature based on the above use-counter: > https://docs.google.com/spreadsheets/d/14w1IoSzW-ZU86U-o6j4VkCugnj_fNxQKNO_x5TEwvPk/edit?usp=sharing > > The majority of sites didn't have any effect when I removed the rule. Of those that did have changes they were: > - Positioning changes of <1em was the primary difference (due to different margin-collapsing logic typically), no > content ended up overlapping. > - One had a somewhat bad visual change due to height (due to margins) being calculated differently. > > I found no sites that were using this feature for what it was intended for. > > I believe if we leave this feature in Blink, it will create compatibility issues for other renderers in the future. > > Firefox: No public signals > Edge: No public signals > Safari: Shipped > > Is this feature fully tested by web-platform-tests? > No > > Link to entry on the Chrome Platform Status > https://www.chromestatus.com/features/5731653806718976 -- Morten Stenshorne, Software developer, Blink/Layout, Google, Oslo, Norway -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/ozziy35k4ene.fsf%40aeneas.osl.corp.google.com.

Daniel Bratell

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Mar 13, 2019, 1:05:15 PM3/13/19

to Morten Stenshorne, Ian Kilpatrick, Ojan Vafai, blink-dev

LGTM3

/Daniel

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