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From: bjoern@drdhh.hanse.de (Bjoern Kriews)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: detecting GDOS and using vst_load_fonts
Message-ID: <3269.11.27@drdhh.hanse.de>
Date: 2 Jun 91 21:50:17 GMT
References: <A1987909308@thelake.mn.org>
Organization: Digital Island
Lines: 114

From article <A1987909308@thelake.mn.org>, by steve@thelake.mn.org (Steve Yelvington):
> 	fonts_loaded =  vst_load_fonts(handle,2);
> /* BOOM! Three big ones and we go no further */

I think you should use 0 instead of 2 because the parameter 'select' is
reserved in Atari-GEM and has to be zero.

I've once written a 'Device Info' program in Turbo-C - you give a device
number from assign.sys - if the devno is equivalent to the value returned 
by graf_handle() it will open a virtual workstation otherwise it'll load
the driver for a physical one. The program checks for GDOS available and
decides whether to open phys_wk/load_fonts or not. It also prints a font-
list. Be aware: Some drivers (printer, plotter...) use different values
for non-existent or default fonts, the tests performed in di.c are not 
taken from any documentation, they ayre just what I figured out.

It uses a Turbo-C library function called vq_gdos() which is official and
implemented as follows:

vq_gdos:
	MOVEQ.L   #-$02,D0
	TRAP      #2
	ADDQ.W    #2,D0
	RTS

I append the source for this little program because I think it is of
general interest:

/*
 *	device info - display information about vdi devices / Turbo-C 2.00
 *	Note: GEM arrays don't hae to be declared when using TC
 *
 *	ANY NOTES, TIPS, HINTS, BUGS, BUGFIXES -> bjoern@drdhh.hanse.de
 *  thanks
 */

#include <vdi.h>
#include <aes.h>
#include <stdio.h>

main(void)
{
	int 	gh,h,i,dev,ret;
  int 	in[11],out[57];
  int		p[10],numfnt;
	char 	fnt[32];

	appl_init();

	gh=h=graf_handle(&i,&i,&i,&i);

	printf("Enter device number: ");
	scanf("%d\n",&dev);

	if(dev!=gh) 
		{
			if(!vq_gdos())
				{
					printf("Can't open physical workstations without GDOS\n");
					appl_exit();
					return 1;
				}
		}

  in[0]=dev;  
  for(i=1;i<10;in[i++]=1);
  	in[10] = 2;

  (dev==gh ? v_opnvwk : v_opnwk)(in,&h,out);

  if(!h)
  	{
    	printf("can't open workstation\n");
      appl_exit(); 
			return 1;
    }

	printf("Handle is %d\n",h);
	printf("Physical Resolution is %u * %u, %d colors\n",
	out[0]+1,out[1]+1,out[13]);
	printf("Pixels are %d um * %d um\n",out[3],out[4]); 	

	if(vq_gdos())
		{
			printf("Loading fonts...\n");
			numfnt=vst_load_fonts(h,0);
			printf("Loaded %d font%s.\n",numfnt,numfnt==1 ? "" : "s");


			printf("Available fonts:\n");
			for(i=1;i<=numfnt+1;++i)
				{
					ret=vqt_name(h,i,fnt);

					if(!(i>1 && (ret==1 || ret==-1)))
						printf("%2d. ID %3d Name: %-32.32s\n",i,ret,fnt);
				}

			vst_unload_fonts(h,0);
		}
	else
		printf("No fonts without GDOS\n");

  (dev==gh ? v_clsvwk : v_clswk)(h);  
  appl_exit();
  return 0;
}
    
Hope that helps, 
	Bjoern   

---
bjoern@drdhh.hanse.de = Bjoern Kriews / Stormsweg 6 / 2000 Hamburg 76 / FRG
"gaaga mahwe Bjoern urgl ufzae Turbo-C bnub"     (J. Willamowius)