setvisualpage


Syntax
#include <graphics.h>
void setvisualpage(int page);
Description
setvisualpage makes page the visual graphics page.

Return Value
None.

See also
graphresult
setactivepage
swapbuffers

Example
/* setvisualpage example */ 

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

int main(void)
{
   /* select driver and mode that supports multiple pages */
   int gdriver = EGA, gmode = EGAHI, errorcode;
   int x, y, ht;

   /* initialize graphics and local variables */
   initgraph(&gdriver, &gmode, "");

   /* read result of initialization */
   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 */
   }

   x = getmaxx() / 2;
   y = getmaxy() / 2;
   ht = textheight("W");

   /*  select the off screen page for drawing */
   setactivepage(1);

   /* draw a line on page #1 */
   line(0, 0, getmaxx(), getmaxy());

   /* output a message on page #1 */
   settextjustify(CENTER_TEXT, CENTER_TEXT);
   outtextxy(x, y, "This is page #1:");
   outtextxy(x, y+ht, "Press any key to halt:");


   /* select drawing to page #0 */
   setactivepage(0);

   /* output a message  on page #0 */
   outtextxy(x, y, "This is page #0.");
   outtextxy(x, y+ht, "Press any key to view page #1:");
   getch();

   /* select page #1 as the visible page */
   setvisualpage(1);

   /* clean up */
   getch();
   closegraph();
   return 0;
}

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