函数名: setviewport

功 能: 为图形输出设置当前视口

用 法: void far setviewport(int left, int top, int right, int bottom, int clipflag);

程序例:

#include <graphics.h>

#include <stdlib.h>

#include <stdio.h>

#include <conio.h>

#define CLIP_ON 1 /* activates clipping in viewport */

int main(void)

{

/* request auto detection */

int gdriver = DETECT, gmode, errorcode;

/* initialize graphics and local variables */

initgraph(&gdriver, &gmode, "");

/* read result of initialization */

errorcode = graphresult();

if (errorcode != grOk) /* an error occurred */

{

printf("Graphics error: %s\", grapherrormsg(errorcode));

printf("Press any key to halt:");

getch();

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

}

setcolor(getmaxcolor());

/* message in default full-screen viewport */

outtextxy(0, 0, "* <-- (0, 0) in default viewport");

/* create a smaller viewport */

setviewport(50, 50, getmaxx()-50, getmaxy()-50, CLIP_ON);

/* display some text */

outtextxy(0, 0, "* <-- (0, 0) in smaller viewport");

/* clean up */

getch();

closegraph();

return 0;

}