MFC画带箭头的直线

构造一个函数，是在startPoint,endPoint间画一条带箭头的线段：
void CTry1View::DrawLine(POINT startPoint, POINT endPoint)
{
CClientDC dc(this);
dc.MoveTo(startPoint);
dc.LineTo(endPoint);

double PI = 3.1415926;
double t=PI/4; //箭头与直线夹角
double l=0.2; //箭头边长度占直线长度的百分比

POINT arrowPoint;

arrowPoint.x = (int)(l*((startPoint.x-endPoint.x)*cos(t)-(startPoint.y-endPoint.y)*sin(t))+endPoint.x);
arrowPoint.y = (int)(l*((startPoint.x-endPoint.x)*sin(t)+(startPoint.y-endPoint.y)*cos(t))+endPoint.y);
dc.MoveTo(endPoint);
dc.LineTo(arrowPoint);

arrowPoint.x = (int)(l*((startPoint.x-endPoint.x)*cos(-t)-(startPoint.y-endPoint.y)*sin(-t))+endPoint.x);
arrowPoint.y = (int)(l*((startPoint.x-endPoint.x)*sin(-t)+(startPoint.y-endPoint.y)*cos(-t))+endPoint.y);
dc.MoveTo(endPoint);
dc.LineTo(arrowPoint);
}