Q40350: _getimage Buffer May Be Huge (Larger than 64K)

Article: Q40350
Product(s): See article
Version(s): 5.00 5.10
Operating System(s): MS-DOS
Keyword(s): ENDUSER | S_QuickC | mspl13_c
Last Modified: 16-JAN-1989

The graphics functions _getimage and _putimage may be used to store
and display graphic images that require a buffer size larger than 64K.
Even though these functions specify that the storage buffer is a far
pointer, _getimage and _putimage internally treat the buffer as huge
and do 32-bit address arithmetic.

The following program demonstrates using the image functions on a huge
image.

/********************************************************************
 * Example program to demonstrate using the functions _getimage and *
 * _putimage on a huge image.                                       *
 ********************************************************************/

#include <stddef.h>
#include <malloc.h>
#include <process.h>
#include <graph.h>

void main (void)
 { long size;
   char far *image;

   /* Put the display in a VGA mode and allocate a huge buffer. */
   if (_setvideomode(_VRES16COLOR)==0)
       { _outtext ("Video mode not supported!\n");
         exit (0);
       }

   /* In _VRES16COLOR, size is 153604. */
   size = _imagesize(0,0,639,479);

   if ( (image=halloc(size,1)) == NULL)
       { _outtext ("Not enough memory for buffer!\n");
         exit (0);
       }

   /* Draw a couple shapes and capture the screen. */
   _ellipse (_GBORDER,0,0,639,479);
   _rectangle (_GBORDER,0,0,639,479);
   _getimage (0,0,639,479,image);

   /* Clear the screen and redraw the image. */
   _clearscreen (_GCLEARSCREEN);
   _putimage (0,0,image,_GOR);

   hfree (image);
 }

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