713856 - Dynamic change of DOM in lists before block element creates blank line

Status: RESOLVED FIXED

(Core :: Layout: Block and Inline, defect, P3)

Description

[Steef]

Attachment: Testcase

If there is a newline in a list before a block element it gets stripped off.

What to do:
Change the textelement containing the newline with javascript to the same content.

Excepted result:
No change in display, newline should not be shown.

Actual result:
Newline is shown in rendered page.


May be relate to Bug 697793 and Bug 690164

Comment 1

[Alice0775 White]

Regression window:
Works;
http://hg.mozilla.org/mozilla-central/rev/c0dbdafa583c
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b8pre) Gecko/20101104 Firefox/4.0b8pre ID:20101104134944
Fails:
http://hg.mozilla.org/mozilla-central/rev/52a6a18eeb61
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b8pre) Gecko/20101104 Firefox/4.0b8pre ID:20101104165457
Pushlog:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=c0dbdafa583c&tochange=52a6a18eeb61

Triggered by:
ed0befc22bb7	Ehsan Akhgari — Bug 389321 - Part 3: Use a centralized algorithm for caret positioning; r=roc a=blocking-betaN+

Comment 2

[Boris Zbarsky [:bzbarsky]]

So presumably the only reason the newline doesn't show up the first time is due to the frame-construction-time whitespace frame suppression?

Comment 3

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

My guess (untested) would be that this is another regression from bug 389321, and likely a duplicate of one of the existing regressions from it.

Comment 4

[Boris Zbarsky [:bzbarsky]]

> My guess (untested) would be that this is another regression from bug 389321,

Comment 1 says so too, based on a bisect.

Comment 5

[(no longer active)]

This seems to be the code responsible for this bug: http://hg.mozilla.org/mozilla-central/rev/ed0befc22bb7#l15.12

Comment 6

[(no longer active)]

(In reply to Boris Zbarsky (:bz) from comment #2)
> So presumably the only reason the newline doesn't show up the first time is
> due to the frame-construction-time whitespace frame suppression?

I think this is the reason, since the code in question doesn't get run the first time that the document is reflown.  Can you please point me to the code responsible for the whitespace frame suppression?  Why don't we do the same thing on the future reflows?

Comment 7

[Robert O'Callahan (:roc) (email my personal email if necessary)]

It's an optimization that happens at frame construction time. When you assign to the node data, we undo the optimization ... it's simpler than trying to keep it optimized through dynamic changes.

Comment 8

[(no longer active)]

Do we undo the optimization only for the textframe that changed?  Note that in this case, the textframe before the <p> element (containing a "\n") triggers this bug.

Comment 9

[Robert O'Callahan (:roc) (email my personal email if necessary)]

(In reply to Ehsan Akhgari [:ehsan] from comment #8)
> Do we undo the optimization only for the textframe that changed?

Yes. The optimization really has nothing to do with this though.

Comment 10

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Attachment: static testcase

Here's a testcase where the empty-textframe optimization never kicks in (because the whitespace-only text node between the <li> and <p> is not adjacent to a block element boundary), which shows the bug.

Comment 11

[(no longer active)]

Attachment: Patch (v1)

Oh, I figured out the problem.  This change had snuck its way into the patch for bug 389321.  It's not needed, and reverting it fixes this bug.

Comment 13

[(no longer active)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/36cd5cc8a909

Comment 14

[Mozilla RelEng Bot]

Try run for 33568bb15cbb is complete.
Detailed breakdown of the results available here:
    https://tbpl.mozilla.org/?tree=Try&rev=33568bb15cbb
Results (out of 222 total builds):
    exception: 5
    success: 187
    warnings: 26
    failure: 4
Builds (or logs if builds failed) available at:
http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/[e-mail]-33568bb15cbb
 Timed out after 06 hours without completing.

Comment 15

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/36cd5cc8a909