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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