给出两个点的BLH，以这两个点给一条边，以给定长度为宽，求定矩形另外两个点的BLH。 里面应用到了高斯投影的运算，及DLL控件的调用等。-Are given two points BLH, one of these two points, to edge to a given length of wide rectangular order to set the other two points of BLH. Which applied to the Gauss projection op