#include <stdio.h>
#include <dos.h>
#include <graphics.h>
 
#define TIME_BUF_LEN 6
#define DATE_BUF_LEN 10
 
#define TIME_TEXT_TEMPLATE "00:00"
#define DATE_TEXT_TEMPLATE "00.00.0000"
 
#define NOTE_TEXT "Press any key to exit..."
 
#define BGI_LOCATION "C:\\TC\\bgi"
 
int gl_nMaxX = 0;
int gl_nMaxY = 0;
 
int gl_nCenterX = 0;
int gl_nCenterY = 0;
 
char gl_szTimeBuff[TIME_BUF_LEN];
char gl_szDateBuff[DATE_BUF_LEN];
 
int initGraphics( void )
{
	int nGraphicDriver = DETECT; 
	int nGraphMode;
	int nErrorCode;
 
	/* Initialize graphics system */
	initgraph(&nGraphicDriver, &nGraphMode, BGI_LOCATION);
	nErrorCode = graphresult();
 
	if (nErrorCode != grOk)
	{
	   return -1;
	}        
 
	/* Graphics OK, so return "true" */
	return 1; 
}
 
void drawNote()
{
	int textWidth, textHeight;
 
	settextstyle(DEFAULT_FONT, HORIZ_DIR, 0);
 
	textWidth = textwidth(NOTE_TEXT);
	textHeight = textheight(NOTE_TEXT);
 
	outtextxy(gl_nMaxX - textWidth,
			  gl_nMaxY - textHeight,
			  NOTE_TEXT);
}
 
void drawTime(struct time *pTime)
{
	int textWidth, textHeight;
 
	settextstyle(SANS_SERIF_FONT, HORIZ_DIR, 8);
 
	textWidth = textwidth(TIME_TEXT_TEMPLATE);
	textHeight = textheight(TIME_TEXT_TEMPLATE);
 
	sprintf(gl_szTimeBuff, "%02d:%02d", pTime->ti_hour, pTime->ti_min);
 
	outtextxy(gl_nCenterX - (textWidth / 2), 
			  gl_nCenterY - textHeight, 
			  gl_szTimeBuff);
}
 
void drawDate(struct date *pDate)
{
	int textWidth;
 
	settextstyle(SANS_SERIF_FONT, HORIZ_DIR, 6);
 
	textWidth = textwidth(DATE_TEXT_TEMPLATE);
 
	sprintf(gl_szDateBuff, 
			"%02d.%02d.%d", 
			pDate->da_day, 
			pDate->da_mon, 
			pDate->da_year);
 
	outtextxy(gl_nCenterX - (textWidth / 2), gl_nCenterY, gl_szDateBuff);
}
 
int main(void)
{
	struct time sysTime, startTime;
	struct date sysDate, startDate;	
 
	if(initGraphics() == -1)
	{
		printf("Error initializing BGI!\n");
		return 0;
	}
 
	gl_nMaxX = getmaxx();
	gl_nMaxY = getmaxy();
 
	gl_nCenterX = (getmaxx() / 2);
	gl_nCenterY = (getmaxy() / 2);		
 
	drawNote();
 
	gettime(&startTime);
	drawTime(&startTime);
 
	getdate(&sysDate);
	drawDate(&sysDate);
 
	while(!kbhit())
	{										
		gettime(&sysTime);
 
		/*
		 * To avoid flickering, redraw the screen only if there are 
		 * changes in the hour or minute values. Only some VGA and EGA
		 * drivers support 'setactivepage()' and 'setvisualpage()'.
		 */
		if(sysTime.ti_hour > startTime.ti_hour || 
		   sysTime.ti_min > startTime.ti_min)
		{
			cleardevice();
			getdate(&sysDate);
 
			drawNote();
			drawTime(&sysTime);
			drawDate(&sysDate);
 
			gettime(&startTime);
		}
	}
 
	closegraph();
 
	return 0;
}