Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!tut.cis.ohio-state.edu!ucbvax!hplabs!hpfcdc!stroyan
From: stroyan@hpfcdc.HP.COM (Mike Stroyan)
Newsgroups: comp.sys.hp
Subject: Re: HP GKS GESC_FILDES question?
Message-ID: <5570179@hpfcdc.HP.COM>
Date: 13 May 89 02:01:05 GMT
References: <47500008@uxe.cso.uiuc.edu>
Organization: HP Ft. Collins, Co.
Lines: 65

> To do this you have to have a file descriptor
> for the open workstation you are using.  To get
> this file descriptor you need to call a special
> "escape" function: gescape.

You need to use the GKS "escape" function, gesc(), rather than the
Starbase "escape" function, gescape().  The program below demonstrates
the use of GESC_FILDES for a workstation display device.

Mike Stroyan, stroyan@hpfcla.hp.com

/*
 * test hpgks GESC_FILDES ESCAPE
 */
#include <stdio.h>
#include <fgks.c.h>
#define NBYTES 0
#define ERROUT stderr
#define CONID  5
#define WSTYP  5
main()
{
	int i, fildes;
	int ia[3], oa[3], il, lidr, lodr, dummy, errind;
	char idr[80], odr[80];

	/*
	 *  Open the workstation and GKS
	 */
	gopks( ERROUT, NBYTES );
	gopwk( 1, CONID, WSTYP );
	gacwk( 1 );

	/*
	 * Pack data record
	 */
	ia[0] = 1; /* Workstation id */
	gprec(1, ia, 0, 0, 0, 0, 0, 1, &errind, &lidr, idr);
	if ( errind )
		fprintf(stderr, "GKS error %d in function %s\n", errind, "gprec");

	/*
	 * Call gesc to determine active file descriptor
	 */
	gesc(GESC_FILDES, lidr, idr, 1, &lodr, odr);

	/*
	 * Unpack data record
	 */
	gurec(lodr, odr, 1, 0, 0, &errind, &il, oa, &dummy, 0, &dummy, 0, 0 );
	if ( errind )
		fprintf(stderr, "GKS error %d in function %s\n", errind, "gurec");

	if ( il > 0 ) {
		fildes = oa[0];
		printf("fildes = %d\n", fildes);
	}

	/*
	 *   Close the workstation and shut down GKS.
	 */
	gdawk ( 1 );
	gclwk ( 1 );
	gclks();
}