Re: State of NS port

[Jan Djärv]

Hello.

12 jan 2013 kl. 04:49 skrev Chris Zheng <address@hidden>:

> I suffered this problem too, and it's because of two bug fixes after I dig it 
> awhile.
> 
> bug#11484: 23.4; Scrolling leaves traces of old text behind
> 
> http://lists.gnu.org/archive/html/bug-gnu-emacs/2012-05/msg00383.html
> 
> LCD-smoothing was turned off to fix this bug,
> 
> and 
> 
> bug#11541: - Another reproduction - Emacs 24.2;       Null pointer on OSX with
> 
> http://lists.gnu.org/archive/html/bug-gnu-emacs/2012-09/msg01293.html
> 
> I simply revert these two fixes, and problem you mentioned is gone. 
> 
> So, maybe there are more deeper things around of these two bugs.

Yes there are.  The first one is due to the fact that the font code 
miscalculates the font metrics when lcd-smoothing is on. It may be related to 
some premature optimizations such as caching of font metrics in the font code.

The second one is because the memory handling in the font code is incorrect and 
leads to crashes for some people (may depend on font and/or OS version and/or 
compiler version/settings).  The second one does not happen when run in gdb.  
But when it does happen, as it does for me right now, Emacs crashes.

        Jan D.