1712703 - `white-space:pre-wrap` does not interact correctly with `text-align:right` or `center`

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, defect)

Description

[Jonathan Kew [:jfkthame]]

Testcase: https://codepen.io/jfkthame/pen/rNywVMB

When white-space:pre-wrap and text-align:right are in effect, we wrap lines after spaces (correctly), but then the space where the line was wrapped occupies space on the line instead of hanging, and means that the text is not properly flush-right.

This behavior would be correct for white-space:break-spaces, where it is explicitly called out in the spec as a difference from pre-wrap behavior; but for pre-wrap, the end-of-line space should hang.

FTR, Chrome also fails the example in this codepen, whereas Safari handles it correctly.

Comment 1

[Jonathan Kew [:jfkthame]]

The same issue applies with text-align:center, where the preserved end-of-line spaces cause the wrapped lines to appear slightly off-center, though it's less obvious than the flush-right case. Example with centered text: https://codepen.io/jfkthame/pen/KKWqpbP

Again, this renders correctly in Safari but wrong in Chrome.

Comment 2

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1712703 - Add WPT reftests for white-space:pre interaction with text-align. r=#layout-reviewers

Of the 15 cases here (combinations of text-align and directionality), mozilla-central
currently fails 9 and passes only 6.

(FTR, a bunch of these tests also currently fail in Chrome, with similar errors to Firefox;
only Safari seems to handle them consistently/correctly.)

Comment 3

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1712703 - Record the "hangable" advance of trailing whitespace in a textframe property, and use this in nsLineLayout to adjust inline positioning. r=#layout-reviewers

Depends on D174726

Comment 4

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1712703 - Remove annotations for failures related to pre-wrap and hanging spaces. r=#layout-reviewers

With the preceding patch, all the new testcases added here now pass, as do several
pre-existing WPT tests that were failing for similar reasons.

Depends on D174728

Comment 5

[Daniel Holbert [:dholbert]]

only Safari seems to handle them consistently/correctly.

I confirmed this -- though interestingly, WebKit-based Epiphany (aka gnome-web), which I tested before Safari here, doesn't seem to handle the preserved-spaces pieces of your codepens correctly. They render your right-aligned example https://codepen.io/jfkthame/pen/rNywVMB without any visible spaces at the right edge in the bottom section; and they render https://codepen.io/jfkthame/pen/KKWqpbP without the expected leftwards-offsetting at the bottom.

Not sure if this is due to platform-differences on Linux vs. Mac, or gnome-web lacking the WebKit code patch to do this properly, or something else.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/fa98b4c11d52
Add WPT reftests for white-space:pre interaction with text-align. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/e54195c66f87
Record the "hangable" advance of trailing whitespace in a textframe property, and use this in nsLineLayout to adjust inline positioning. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/18c753fda684
Remove annotations for failures related to pre-wrap and hanging spaces. r=dholbert

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/39399 for changes under testing/web-platform/tests

Comment 8

[Noemi Erli[:noemi_erli]]

Backed out 3 changesets (Bug 1712703) for causing nsLineLayout related crashes CLOSED TREE

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&group_state=expanded&collapsedPushes=842382&selectedTaskRun=CvxhJjEIQmC79D6N8i-Grg.0&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=18c753fda6845fb92ca63a36f1b0ad19e97aafca

Log: https://treeherder.mozilla.org/logviewer?job_id=411520709&repo=autoland&lineNumber=9151
https://treeherder.mozilla.org/logviewer?job_id=411521219&repo=autoland&lineNumber=9199

Backout: https://hg.mozilla.org/integration/autoland/rev/049e50697d7c8d63c4ffef301c4cbe0c3c097e12

Comment 9

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

Upstream PR was closed without merging

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0c96eb4bdfd1
Add WPT reftests for white-space:pre interaction with text-align. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/d2bee1af043f
Record the "hangable" advance of trailing whitespace in a textframe property, and use this in nsLineLayout to adjust inline positioning. r=dholbert
https://hg.mozilla.org/integration/autoland/rev/5c2a1049afaa
Remove annotations for failures related to pre-wrap and hanging spaces. r=dholbert

Comment 11

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/0c96eb4bdfd1
https://hg.mozilla.org/mozilla-central/rev/d2bee1af043f
https://hg.mozilla.org/mozilla-central/rev/5c2a1049afaa

Comment 12

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

Upstream PR merged by moz-wptsync-bot