Bug 87041 – Ideographic comma and full-stops are mishandled in linebreak

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Jungshik Shin]

Copied from our internal investigation: 

----------

The problem is in shouldBreakAfter() of Source/WebCore/rendering/break_lines.cpp.

 static inline bool shouldBreakAfter(UChar ch, UChar nextCh)
 {
   switch (ch) {
   case ideographicComma:
   case ideographicFullStop:
       // FIXME: cases for ideographicComma and ideographicFullStop are a workaround for an issue in Unicode 5.0
       // which is likely to be resolved in Unicode 5.1 <http://bugs.webkit.org/show_bug.cgi?id=17411>.
       // We may want to remove or conditionalize this workaround at some point.

       return true;
   default:
   ....


shouldBreakAfter() hard coded a line break after ideographicComma and ideographicFullStop regardless any other punctuation right after these 2 characters. 
-----------------

The above issue is not present any more in ICU 4.0 or later. Chrome uses ICU 4.6. The other major port that uses ICU is Safari. I'm sure Safari Windows uses ICU 4.0 or later. The question boils down to the version of ICU on the earliest version of Mac OS X that Safari has to support. If it's ICU 4.0 or alter, we can just remove two hard-coded cases above (ideographicComma and ideographicFullStop). 

Otherwise, either we have to detect the ICU version at run-time and do different things or at least we have to fix Chromium and Safari on Windows with #if-def (build-time check). 


darin or ap, can you tell us the version of ICU on the earliest version of Mac OS X Safari has to support?

[Darin Adler]

ICU 4.0 is there on Snow Leopard, so the only issue is Leopard. The Apple folks are not expecting to support Leopard with the current WebKit TOT, so it would be OK to remove this completely from the Apple Mac port point of view.

[Jungshik Shin]

Thank you, Darin, for the reply. (I was OOO for a while). I'll make a patch to remove it.

<rdar://problem/11215797>

Created attachment 148157 [details]
Remove the unconditional line breaking opportunity after ideographic commas and full stops

Fixed in <http://trac.webkit.org/r120624>.

[Csaba Osztrogonác]

(In reply to comment #5)
> Fixed in <http://trac.webkit.org/r120624>.

It made a test fail on Qt. Could you check it, please? I file a new bug report to track this new regression - https://bugs.webkit.org/show_bug.cgi?id=89426

(In reply to comment #6)
> (In reply to comment #5)
> > Fixed in <http://trac.webkit.org/r120624>.
> 
> It made a test fail on Qt. Could you check it, please? I file a new bug report to track this new regression - https://bugs.webkit.org/show_bug.cgi?id=89426

That’s an odd way to put it. The test was added as part of this change.

[Csaba Osztrogonác]

(In reply to comment #7)
> That’s an odd way to put it. The test was added as part of this change.
Oh, I overlooked it, I fixed the title of the bug.