已知两端点, 画工字线

已知两端点, 画工字线
如图所示
p1, p2

	double dHead = 10;		// 工字头的半长
	double dLen = sqrt(double((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y)));


	int	nX = (int)((p1.y - p2.y) * dHead / dLen + 0.5);
	int nY = (int)((p1.x - p2.x) * dHead / dLen + 0.5);
	
	pDC->MoveTo(p1.x - nX, p1.y + nY);
	pDC->LineTo(p1.x + nX, p1.y - nY);
	pDC->MoveTo(p2.x - nX, p2.y + nY);
	pDC->LineTo(p2.x + nX, p2.y - nY);