- (void) drawTime : (float) hour  min : (float) min {
	CGContextRef context = UIGraphicsGetCurrentContext();
	CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);


	// min hand
	float mAngle = (90 - 6*min)*PI / 180;
	float mX = XC + M_LEN * cos(mAngle);
	float mY =  MARGIN + RADIUS  - M_LEN * sin(mAngle);

	MOVE_TO_CTR();
   CGContextAddLineToPoint(context,mX, mY);
	CGContextStrokePath(context);
	CGContextAddEllipseInRect(context,  CGRectMake(mX-5,mY-5, 10, 10));
	CGContextDrawPath(context, kCGPathFillStroke);

	// Hour hand
	float hAngle = (90 - 30*hour)*PI / 180;
	float hX = XC + H_LEN * cos(hAngle);
	float hY =  MARGIN + RADIUS  - H_LEN * sin(hAngle);

	MOVE_TO_CTR();
	CGContextAddLineToPoint(context,hX, hY);
	CGContextStrokePath(context);
	CGContextAddEllipseInRect(context,  CGRectMake(hX-5,hY-5, 10, 10));
	CGContextDrawPath(context, kCGPathFillStroke);

}