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 楼主|
发表于 2004-5-10 16:42:13
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| <  >函数名: setvisualpage 功  能: 设置可见图形页号
 用  法: void far setvisualpage(int pagenum);
 程序例: <
  >#include <graphics.h> #include <stdlib.h>
 #include <stdio.h>
 #include <conio.h> <
  >int main(void) {
 /* select a driver and mode that supports */
 /* multiple pages.                        */
 int gdriver = EGA, gmode = EGAHI, errorcode;
 int x, y, ht; <P>   /* initialize graphics and local variables */
 initgraph(&gdriver, &gmode, ""); <P>   /* 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 */
 } <P>   x = getmaxx() / 2;
 y = getmaxy() / 2;
 ht = textheight("W"); <P>   /*  select the off screen page for drawing */
 setactivepage(1); <P>   /* draw a line on page #1 */
 line(0, 0, getmaxx(), getmaxy()); <P>   /* 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:"); <P>   /* select drawing to page #0 */
 setactivepage(0); <P>   /* 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(); <P>   /* select page #1 as the visible page */
 setvisualpage(1); <P>   /* clean up */
 getch();
 closegraph();
 return 0;
 }
 
 </P>
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