Re: form_driver and wide-char

[Brian Tan]

Thomas Dickey wrote:
> On Thu, Dec 07, 2006 at 11:24:41AM -0500, Brian Tan wrote:
>   
> > limited success with form_driver() and mbs using getch. Some chars went 
> > through correctly into field buffer, while others get clobbered.  
> > However, screen update is always garbled. Attached sample program and 
> > test data.
> >     
>
> I can see two problems.
>
> One is a known limitation (something that could be improved but make it
> slower).  ncurses's addch only handles wide characters properly if it's
> continuing to update the same cell in a given window.
>
> That's usually not a problem, since most applications complete a wide
> character before moving the current position.
>
> Printing the bytes individually in the window as they're read will
> cause it to be confused, since the current position changes.
>
>   
> Your test program doesn't happen to be affected, since the form is
> in one window, and you're printing bytes to stdscr - but it's something
> to watch out for.
>
>   

> The other is something that can be fixed in the test program - moving the
> setlocale call before initscr.  Just doing that makes your program work -
> for me.
>
>   
I thought the problem was locale problem. I had setlocale() before 
initscr() in another test program and it worked. Too much messing around 
to test out scenarios. :( My bad.
> > # export LANG=en_US.UTF-8
> > # gcc -O2 -g testform.c -o testform -lncursesw -lformw
> > # testform <testform.txt
> >
> > Char that went through: ??? e5a5bd
> > Char went bad: ??? e99988
> >
> > Also field buffer advanced incorrectly after widechar. (gap between '???' 
> > and 'a')
> >
> > Thomas Dickey wrote:
> >     
> > > > 1. field_buffer(); it does not return mbs correctly. For example, 
> > > > wchar 0x597d -> mbs e5a5bd written with set_field_buffer(), screen 
> > > > form updates and shows ?????? " (with trailing space due to strlen=3, I 
> > > > think) but field_buffer() returns c3a5c2a5c2bd, making further wchar 
> > > > entry not possible, unless I keep track of field buffer independently.
> > > >         
> > > This is probably the best place to focus on right now.
> > > The two (I think) are independent
> > >       
> > > > 2. form_driver; for not accepting wchar or mbs :)
> > > >         
> > > It's supposed to do the latter - but it's likely that you're better 
> > > able to see problems.  I tested it by select/paste from the UTF-8 
> > > scripts in
> > > the dialog package, combined with editing from the keyboard.  At the same
> > > time, my test program would set/get from the field buffer, so I could 
> > > see mismatches.
> > >
> > > So - going back to testing this area, along with some sample data (and 
> > > locale information from you) would help to reproduce the problem and 
> > > focus on what's going wrong.
> > >
> > > thanks
> > >
> > >       
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> >     
>
>
>
>   


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