nanogui: Thread: question about GrOpen()..

When we port oms (a dvd player) to naon-X, we find
ourselves in trouble with GrOpen function. It returns
success when first called but failed in second. The problem
is our UserInterface call it first time to connect nano-X
graphics server, which is ok. But when UI calls play
function, it in turn calls open_display which calls GrOpen
to open display and return fail. If we don't use GrOpen
here, we will not be able to get output. Does anybody know
how to do this? or other method to check whether nano-X
server is already running?

thanks in advance,

L.C. Chang

On Wed, 28 Feb 2001, LC. Chang wrote:
> When we port oms (a dvd player) to naon-X, we find
> ourselves in trouble with GrOpen function. It returns
> success when first called but failed in second. The problem

It is not possible (or necessary) for an application to open more than
one connection to the server at a time.

> to open display and return fail. If we don't use GrOpen
> here, we will not be able to get output. Does anybody know

Why not?

-- 
------- Alex Holden -------
http://www.linuxhacker.org/
 http://www.robogeeks.org/

:it in turn calls open_display which calls GrOpen
: to open display and return fail. If we don't use GrOpen
: here, we will not be able to get output. Does anybody know
: how to do this? or other method to check whether nano-X
: server is already running?

I've had this problem before when porting certain
programs to Nano-X that support talking to multiple
windowing systems, and want to know whether the
Nano-X server is running or not.

The solution I've used is to use GrOpen() check the
return value, and if OK, then call GrClose().  Afterwards,
you can then call GrOpen() again and it should work.
We made need to add a different open call sometime if
this doesn't work for you.

Regards,

Greg

Sorry I have not made myself clear.

The application is a dvd player and the UI made by FLTK
will call oms library to play dvd title. The oms library
will start several threads to process the audio, video... data.
And the video data is output by GrXXX function, which
needs to open nano-X graphic. I had tried GrClose before
GrOpen but still failed. The UI simply exit when GrClose
being called.

Regards,
L.C. Chang

> On Wed, 28 Feb 2001, LC. Chang wrote:
> > When we port oms (a dvd player) to naon-X, we find
> > ourselves in trouble with GrOpen function. It returns
> > success when first called but failed in second. The problem
>
> It is not possible (or necessary) for an application to open more than
> one connection to the server at a time.
>
> > to open display and return fail. If we don't use GrOpen
> > here, we will not be able to get output. Does anybody know
>
> Why not?
>
> --
> ------- Alex Holden -------
> http://www.linuxhacker.org/
>  http://www.robogeeks.org/
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: ####@####.####
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> The solution I've used is to use GrOpen() check the
> return value, and if OK, then call GrClose().  Afterwards,
> you can then call GrOpen() again and it should work.
> We made need to add a different open call sometime if
> this doesn't work for you.

I have tried to write a simple test. I use GrOpen () to connect to
nano-X server, and then call GrClose () to disconnect. When I want to
use GrOpen () to connect to server again, it will fail. My platform is
microwin under X11.

Regards,
Niky

On Thu, 01 Mar 2001 10:30:35 niky wrote:
> > The solution I've used is to use GrOpen() check the
> > return value, and if OK, then call GrClose().  Afterwards,
> > you can then call GrOpen() again and it should work.
> > We made need to add a different open call sometime if
> > this doesn't work for you.
> 
> I have tried to write a simple test. I use GrOpen () to connect to
> nano-X server, and then call GrClose () to disconnect. When I want to
> use GrOpen () to connect to server again, it will fail. My platform is
> microwin under X11.
> 


The problem is in GrClose() in the client. Edit the file
".../microwin/src/nanox/client.c". Look for GrClose(), add the line
"nxSocket = -1;" to the end of the function. Then all will work well. ie:

CHANGE THIS:

  void 
  GrClose(void)
  {
  #if GR_CLOSE_FIX
      /* allow 1 second to flush*/
      void * oldSignalHandler = signal(SIGALRM, mySignalhandler);
      alarm(1);
  #endif
      AllocReq(Close);
      GrFlush();
  #if GR_CLOSE_FIX
      alarm(0);
      signal(SIGALRM, oldSignalHandler);
  #endif
     close(nxSocket);
  }

TO THIS:

  void 
  GrClose(void)
  {
  #if GR_CLOSE_FIX
      /* allow 1 second to flush*/
      void * oldSignalHandler = signal(SIGALRM, mySignalhandler);
      alarm(1);
  #endif
      AllocReq(Close);
      GrFlush();
  #if GR_CLOSE_FIX
      alarm(0);
      signal(SIGALRM, oldSignalHandler);
  #endif
      close(nxSocket);
      nxSocket = -1;
  }


Gary James

: I have tried to write a simple test. I use GrOpen () to connect to
: nano-X server, and then call GrClose () to disconnect. When I want to
: use GrOpen () to connect to server again, it will fail. My platform is
: microwin under X11.

This is a bug then.  I thought I'd used this method under framebuffer,
but maybe there's a difference.  I'll look at this soon.  Thanks for the
response.

Regards,

Greg

: The problem is in GrClose() in the client. Edit the file
: ".../microwin/src/nanox/client.c". Look for GrClose(), add the line
: "nxSocket = -1;" to the end of the function. Then all will work well. ie:

Gary: you're the man!!  I'll add this to the tree, thanks.

Regards,

Greg