1579565 - Fix the margin-bottom falsely applied for a block container if it is split by a column-span

Status: RESOLVED FIXED

(Core :: Layout: Columns, defect, P3)

Description

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: multicol-span-all-children-height-008.html

Load the test case attached.

Some unexpected behavior of margin:

1. div.container's margin-bottom is applied in the second column before column-span.
2. block1's margin-bottom seems missing.
3. block2's margin is missing.

Comment 1

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: screenshot (with bug 1523582 patches applied).png

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

There is related discussion in https://phabricator.services.mozilla.com/D43905

Comment 3

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: Bug 1579565 Part 1 - Skip applying the child block's block-end margin when placing it if it has a later sibling across column-span split.

Comment 4

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

Attachment: Bug 1579565 Part 2 - Skip block-end side if the frame has a column-span sibling.

Also, clean up the wording and variable names when aReflowInput is used.

Depends on D47675

Comment 5

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

The proposed patches fix the obvious unexpected behavior (1) in comment 0 that we incorrectly apply container's block-end margin before the column-span split.

Per spec "Adjoining Margins at Breaks",

When a forced break occurs there, adjoining margins before the break are truncated, but margins after the break are preserved.

For (2), column-span split is a kind of force-break (?) to me, so it seems ok we truncate block1's block-end margin. For (3), Chrome and us both lack the block2's block-start margin, so I don't the rush to fix it before shipping column-span.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/614dba91c0b1
Part 1 - Skip applying the child block's block-end margin when placing it if it has a later sibling across column-span split. r=dbaron
https://hg.mozilla.org/integration/autoland/rev/5921da698109
Part 2 - Skip block-end side if the frame has a column-span sibling. r=dbaron

Comment 7

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/19493 for changes under testing/web-platform/tests

Comment 8

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream web-platform-tests status checks passed, PR will merge once commit reaches central.

Comment 9

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/614dba91c0b1
https://hg.mozilla.org/mozilla-central/rev/5921da698109

Comment 10

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot