思路给下，代码就不写了点的结构体两个，一个点a，一个点b左键按下消息时给a点赋值鼠标坐标在左键按下状态移动鼠标时，给b点赋值鼠标坐标，并且用gdi画线，线段的两点间我用符号->连接(a.x,a.y)->(a.x,b.y)(a.x,a.y)->(b.x,a.y)(a.x,b.y)->(b.x,b.y)(b.x,a.y)->(b.x,b.y)
