//由三点计算圆弧的参数：
	//const QRect & rectangle, int startAngle, int spanAngle
	//圆弧的包围框（左上角坐标、宽、高），起始角度、旋转角度
	double radius, x0, y0, startAngle, spanAngle;
	double x1 = dataList.at(0)->x, x2 = dataList.at(1)->x, x3 = dataList.at(2)->x;
	double y1 = dataList.at(0)->y, y2 = dataList.at(1)->y, y3 = dataList.at(2)->y;
	double a = x1 - x2;
	double b = y1 - y2;
	double c = x1 - x3;
	double d = y1 - y3;
	double e = ((x1 * x1 - x2 * x2) + (y1 * y1 - y2 * y2)) / 2.0;
	double f = ((x1 * x1 - x3 * x3) + (y1 * y1 - y3 * y3)) / 2.0;
	double det = b * c - a * d;
	if ((x1 == x2 && x1 == x3) || (y1 == y2 && y1 == y3))
	{
		return;      //三点一线
	}

	x0 = (b * f - d * e) / det;
	y0 = (c * e - a * f) / det;
	radius = hypot(x1 - x0, y1 - y0);

	//计算三点的对应的角度
	double angle1 = acos((x1 - x0) / (hypot((x1 - x0), (y1 - y0))));
	double angle2 = acos((x2 - x0) / (hypot((x2 - x0), (y2 - y0))));
	double angle3 = acos((x3 - x0) / (hypot((x3 - x0), (y3 - y0))));
	if (y1 - y0 < 0)
		angle1 = 2 * PI - angle1;  //点1在第三、四象限

	if (y2 - y0 < 0)
		angle2 = 2 * PI - angle2; //点2在第三、四象限

	if (y3 - y0 < 0)
		angle3 = 2 * PI - angle3; //点3在第三、四象限


	//上面计算的角度是基于QGraphicsView中的坐标，需要进行转换为数学坐标中的角度
	angle1 = 360 - angle1 * 180 / PI;
	angle2 = 360 - angle2 * 180 / PI;
	angle3 = 360 - angle3 * 180 / PI;

	//设置绘制方向
	startAngle = angle1;
	spanAngle = angle3 - angle1;
	if (!data->m_arcDirection)       //顺时针(负值）
	{
		if (spanAngle > 0)
			spanAngle = spanAngle - 360;
	}
	else                           //逆时针(正值）
	{
		if (spanAngle < 0)
			spanAngle = spanAngle + 360;
	}

	//m_angle圆弧在圆上的起点角度，m_spanAngle圆弧的角度
	double arcRecX = x0 - radius;
	double arcRecY = y0 - radius;
	double arcRecW = 2 * radius;
	double arcRecH = 2 * radius;
	double arcStartPhi = startAngle;
	double arcSpanPhi = spanAngle;

	QRect rec;
	rec.setX(arcRecX );
	rec.setY(arcRecY );
	rec.setWidth(arcRecW );
	rec.setHeight(arcRecH );
	painters.drawArc(rec, 16 * arcStartPhi, 16 * arcSpanPhi);  //QT绘制单位就是1/16度，需进行换算