No subject

   /* We are free to run now.  No one is using our socket/FIFOs.
*/
    /* If we are to run in background, we will have foreground == 0 from
*/
    /* the syntax check above. */

    if (!foreground)
    {
#ifndef __NoX__
        if (pid = fork())
#else
	if (pid = 1)
#endif
        {
            if (pid > 0)        /* parent exits */
            {
                fprintf(stderr,"Graphics driver [%s] started\n", me);
#ifndef __NoX__
                exit(0);
#endif
            }

Messy, but it worked.  I used __NoX__ rather than __W98__ to seperate those
set of changes. I recommend following Glynn's much simpler solution.  I
believe that I was just being careful in case someone added additional uses
for the foreground and pid variables in later versions of the code.

The other major change was in XDRIVER/XDRIVER24/Graph_Set.c

    /* Open the display using the $DISPLAY environment variable to
     * locate the X server. Return 0 if cannot open. */
#ifndef __NoX__
    if (!(dpy = XOpenDisplay(NULL))) {
        fprintf(stderr, "Graph_Set: can't open Display %s\n",
XDisplayName(NULL));
#else
    if (!(dpy = XOpenDisplay(""))) {
        fprintf(stderr, "Graph_Set: can't open Display \n");
#endif
        return -1;
    }


This fixes the Null String vs NULL difference that I mentioned earlier.

As I think I identified in April or May, I was successful in getting the
Vector display commands to work, but did not get Raster working.  I haven't
had time to go back to this.

Mike:  Add the defines in my earlier message to xlib.h or some other header,
and you should be able to get vector graphics to work.  There are still a
couple of X function calls that I had excluded (using #ifndef) dealing with
the color map (wonder why the Raster graphics didn't work?), plus the
XNoOp(dpy) in Work.c  (you probably already found that one).

Good Luck,

Malcolm

-----Original Message-----
From: wingrass-admin at grass.itc.it [mailto:wingrass-admin at grass.itc.it]On
Behalf Of Glynn Clements
Sent: Thursday, September 20, 2001 11:34 AM
To: Mike Thomas
Cc: wingrass at grass.itc.it; Roberto Flor
Subject: Re: [winGRASS] Re: generic Windows GRASS driver



Mike Thomas wrote:

> Debugging the libW11 version of the XDriver - the exposition of my logic
may
> be a little laborious, but I am coming to grips with the differences
between
> X11 and Windows from behind the pole position.
>
> OK - further to the report below, it seems that the libW11 display window
> closes down as soon as the parent XDRIVER exits - that is, when the
message:
>
>     Graphics driver [x0] started - exiting
>
> appears.
>
> My interpretation of this is that the new window is not running as a
> separate process and therefore is doomed to die with the process that
> launches it (ie the parent XDriver).
>
> I assume that this is not the case with X11 - that is, that the window is
> under the control of the XServer rather than the XDriver and is therefore
> preserved.

Yep. The child process inherits the descriptor which is the connection
to the X server, allowing it to continue from where the parent left
off.

> On this basis I used the __W98__ define to stop the parent from exiting.
> This buys a display which waits for a response (looping on do_work(0)).

You would also need to disable the fork(). Not only is the child
process is of no use (as it can't make use of the window which the
parent created), it will interfere with the parent (as it will be
reading from the control socket, "stealing" data which should be read
by the parent).

This simplest way to avoid the fork is to add the following at an
appropriate point in main.c:

	#ifdef __W98__
		foreground = 1;
	#endif

--
Glynn Clements <glynn.clements at virgin.net>
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