1763647 - content-visibility: hidden and content-visibility: auto should enable containment

Status: RESOLVED FIXED

(Core :: Layout, enhancement)

Description

[Martin Robinson (email:[e-mail])]

The specification (https://drafts.csswg.org/css-contain/#content-visibility) says:

If an element has a value other than content-visibility: visible, then the following properties hold:

• layout containment ensures that the user-agent is able to omit layout work in skipped subtrees, since the results of such layouts will not affect elements outside of the container element.
• style containment ensures that counters do not have to be processed in skipped subtrees, since they do not affect counters outside of the container element.
• paint containment ensures that ink overflow of painted contents is clipped; this, in turn, means that user-agent can reliably determine when the visible portion of the element approaches the viewport (and, for content-visibility: auto, start painting it).
• size containment ensures that the user-agent is able to omit layout in skipped subtrees, since the results of such layouts will not affect the container element’s size.

Note that in the content-visibility: auto case, layout containment, style containment, and paint containment persist even if the element is not skipped. This is done to prevent layout changes that would be incurred by containment changes as a result of an element entering and exiting the skipped state.

This bug tracks turning on containment based on the content-visibility property.

Comment 1

[Martin Robinson (email:[e-mail])]

Attachment: Bug 1763647 - content-visibility: hidden and content-visibility: auto should enable containment r=emilio,dholbert

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/177edcaff970
content-visibility: hidden and content-visibility: auto should enable containment r=emilio

Comment 3

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/177edcaff970