969147 - Compute flex line cross-sizes earlier on, so we can split paginated flex containers sooner

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Daniel Holbert [:dholbert]]

Filing this bug on a bit of flexbox-layout refactoring, to help with bug 939897.

Right now, we compute the cross-sizes of all the flex items (potentially reflowing every single one), and then we compute the sizes of their flex lines, and then we're in a position to be able to (eventually) see which flex lines fit & which flex lines don't.

Instead, we should compute the sizes of the flex lines as-we-go, so we can split sooner and avoid needless reflows of flex items that aren't going to fit anyway.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: fix v1

This does two things:
 (a) Computes the size of each flex line as early as possible (right after we finish sizing its flex items).

 (b) Sums the sizes of our flex lines more proactively. (so that in bug 939897, we can compare this running total against the available height or width, and trigger a break when it surpasses it)

Comment 2

[Daniel Holbert [:dholbert]]

Landed: https://hg.mozilla.org/integration/mozilla-inbound/rev/43437cbeca1a

Comment 3

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/43437cbeca1a