detectgraph

Syntax

#include <graphics.h>
void detectgraph(int *graphdriver, int *graphmode);

Description

detectgraph detects your system's graphics adapter and chooses the mode that provides the highest resolution for that adapter. If no graphics hardware is detected, *graphdriver is set to grNotDetected (-2), and graphresult returns grNotDetected (-2).

*graphdriver is an integer that specifies the graphics driver to be used. You can give it a value using a constant of the graphics_drivers enumeration type defined in graphics.h and listed as follows:

graphics_drivers constant	Numeric value
DETECT	0 (requests autodetect)
CGA	1
MCGA	2
EGA	3
EGA64	4
EGAMONO	5
IBM8514	6
HERCMONO	7
ATT400	8
VGA	9
PC3270	10

*graphmode is an integer that specifies the initial graphics mode (unless *graphdriver equals DETECT; in which case, *graphmode is set to the highest resolution available for the detected driver). You can give *graphmode a value using a constant of the graphics_modes enumeration type defined in graphics.h and listed as follows.

Graphics			Columns
Driver	graphics_mode	Value	x Rows	Palette	Pages
CGA	CGAC0	0	320 x 200	C0	1
	CGAC1	1	320 x 200	C1	1
	CGAC2	2	320 x 200	C2	1
	CGAC3	3	320 x 200	C3	1
	CGAHI	4	640 x 200	2 color	1
MCGA	MCGAC0	0	320 x 200	C0	1
	MCGAC1	1	320 x 200	C1	1
	MCGAC2	2	320 x 200	C2	1
	MCGAC3	3	320 x 200	C3	1
	MCGAMED	4	640 x 200	2 color	1
	MCGAHI	5	640 x 480	2 color	1
EGA	EGALO	0	640 x 200	16 color	4
	EGAHI	1	640 x 350	16 color	2
EGA64	EGA64LO	0	640 x 200	16 color	1
	EGA64HI	1	640 x 350	4 color	1
EGA-MONO	EGAMONOHI	3	640 x 350	2 color	1 w/64K
	EGAMONOHI	3	640 x 350	2 color	2 w/256K
HERC	HERCMONOHI	0	720 x 348	2 color	2
ATT400	ATT400C0	0	320 x 200	C0	1
	ATT400C1	1	320 x 200	C1	1
	ATT400C2	2	320 x 200	C2	1
	ATT400C3	3	320 x 200	C3	1
	ATT400MED	4	640 x 200	2 color	1
	ATT400HI	5	640 x 400	2 color	1
VGA	VGALO	0	640 x 200	16 color	2
	VGAMED	1	640 x 350	16 color	2
	VGAHI	2	640 x 480	16 color	1
PC3270	PC3270HI	0	720 x 350	2 color	1
IBM8514	IBM8514HI	0	640 x 480	256 color	?
	IBM8514LO	0	1024 x 768	256 color	?

Note: The main reason to call detectgraph directly is to override the graphics mode that detectgraph recommends to initgraph.

Return Value

None.

Windows Notes

The winbgim version of detectgraph returns VGA for the graphdriver and VGAHI for the graphmode, regardless of the machine's hardware. However, the screen is not necessarily 640 x 480.

See also

graphresult

initgraph

Example

/* detectgraph example */ 

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

/* the names of the various cards supported */
char *dname[] = { "requests detection",
                  "a CGA",
                  "an MCGA",
                  "an EGA",
                  "a 64K EGA",
                  "a monochrome EGA",
                  "an IBM 8514",
                  "a Hercules monochrome",
                  "an AT&T 6300 PC",
                  "a VGA",

                  "an IBM 3270 PC"
                };

int main(void)
{
   /* used to return detected hardware info. */
   int gdriver, gmode, errorcode;

   /* detect the graphics hardware available */
   detectgraph(&gdriver, &gmode);

   /* read result of detectgraph call */
   errorcode = graphresult();
   if (errorcode != grOk) {  /* an error occurred */
      printf("Graphics error: %s\n", grapherrormsg(errorcode));
      printf("Press any key to halt:");

      getch();
      exit(1);               /* terminate with an error code */
   }

   /* display the information detected */
   clrscr();
   printf("You have %s video display card.\n", dname[gdriver]);
   printf("Press any key to halt:");
   getch();
   return 0;
}