CAD交互绘制矩形框（com接口）

主要用到函数说明：

_DMxDrawX::DrawLine

绘制一个直线。详细说明如下：

参数	说明
DOUBLE dX1	直线的开始点x坐标
DOUBLE dY1	直线的开始点y坐标
DOUBLE dX2	直线的结束点x坐标
DOUBLE dY2	直线的结束点y坐标

IMxDrawCustomEntity::Draw

把实体绘制到图上。一般用于动态拖放时，在拖放结束时，绘制到图上。

c#中实现代码说明：

动态拖放时的绘制事件：

private void DrawPathToPolyline()
{
    // 创建一个与用户交互取点的对象。
    MxDrawPoint point1 = (MxDrawPoint)axMxDrawX1.GetPoint(false, 0, 0, "\n 点取开始点:");
    if (point1 == null)
    {
        return;
    }
    MxDrawUiPrPoint getSecondPt = new MxDrawUiPrPoint();
    getSecondPt.message = "第二点";
    getSecondPt.basePoint = point1;
    //不开启皮筋效果
    getSecondPt.setUseBasePt(false);
    //调用
    var spDrawData = getSecondPt.InitUserDraw("TestDynDrawMatrix1");
    // 设置动态绘制参数.
    spDrawData.SetPoint("BasePoint", point1);
    // 开始取第二个点。
    if (getSecondPt.go() != MCAD_McUiPrStatus.mcOk)
        return;
    var ret = spDrawData.Draw();
}

动态绘制矩形框：

private void axMxDrawX1_DynWorldDraw(object sender, AxMxDrawXLib._DMxDrawXEvents_DynWorldDrawEvent e)
{
    MxDrawCustomEntity pCustomEntity = (MxDrawCustomEntity)e.pData;
    MxDrawWorldDraw pWorldDraw = (MxDrawWorldDraw)e.pWorldDraw;
    string sGuid = pCustomEntity.Guid;

    MxDrawPoint curPoint = new MxDrawPoint();

    curPoint.x = e.dX;
curPoint.y = e.dY;
    if(sGuid == "TestDynDrawMatrix1")
    {
        //与用户交互在图面上提取一个点
        var vBasePt = pCustomEntity.GetPoint("BasePoint");
        //绘制一个直线
        //参数一直线的开始点x坐标，参数二直线的开始点y坐标，参数三直线的结束点x坐标，参数四直线的结束点y坐标
        pWorldDraw.DrawLine(vBasePt.x, vBasePt.y, vBasePt.x, curPoint.y);
        pWorldDraw.DrawLine(vBasePt.x, curPoint.y, curPoint.x, curPoint.y);
        pWorldDraw.DrawLine(curPoint.x, curPoint.y, curPoint.x, vBasePt.y);
        pWorldDraw.DrawLine(curPoint.x, vBasePt.y, vBasePt.x, vBasePt.y);
    }
}