清除图形视区

[c]代码库

#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;
	int 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 */
	}

	setcolor ( getmaxcolor() );
	ht = textheight ( "W" );

	/* 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 messages */
	outtextxy ( 0, 0, "* <-- (0, 0) in smaller viewport" );
	outtextxy ( 0, 2*ht, "Press any key to clear viewport:" );

	/* wait for a key */
	getch();

	/* clear the viewport */
	clearviewport();

	/* output another message */
	outtextxy ( 0, 0, "Press any key to quit:" );

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