获得平行四边形中，那条较长的中心线

我会带着你远行 2022-08-07 01:33 139阅读 0赞

/// <summary>
            /// 创建平行四边形中，较长的一条中心线
            /// </summary>
            public IGeometry CreateLine(IPolygon pPolygon)
            {
                if (pPolygon == null)
                {
                    return null;
                }
    
                try
                {
                     首先判断pPolygon是否为平行四边形
                    if (!IsParallelogram(pPolygon))
                    {
                        return null;
                    }
    
                    IPointCollection pPointCol = pPolygon as IPointCollection;
    
                    IPoint pFstPt = null;
                    IPoint pSecPt = null;
                    IPoint pTrdPt = null;
                    IPoint pForPt = null;
                     这些点事按照绘制顺序来存储的
                    pFstPt = pPointCol.get_Point(0);
                    pSecPt = pPointCol.get_Point(1);
                    pTrdPt = pPointCol.get_Point(2);
                    pForPt = pPointCol.get_Point(3);
    
                    IPoint pFst = new PointClass();
                    IPoint pSec = new PointClass();
                    IPoint pTrd = new PointClass();
                    IPoint pFor = new PointClass();
                     获得线段中点
                    pFst.PutCoords((pFstPt.X + pSecPt.X) / 2, (pFstPt.Y + pSecPt.Y) / 2);
                    pSec.PutCoords((pSecPt.X + pTrdPt.X) / 2, (pSecPt.Y + pTrdPt.Y) / 2);
                    pTrd.PutCoords((pTrdPt.X + pForPt.X) / 2, (pTrdPt.Y + pForPt.Y) / 2);
                    pFor.PutCoords((pForPt.X + pFstPt.X) / 2, (pForPt.Y + pFstPt.Y) / 2);
    
                    object oBefore = Type.Missing;
                    object oAfter = Type.Missing;
                    ILine pLineLR = new LineClass();
                    pLineLR.PutCoords(pFst, pTrd);
                    ILine pLineUL = new LineClass();
                    pLineUL.PutCoords(pSec, pFor);
    
                    IPolyline pPolylineLR = new PolylineClass();
                    IPolyline pPolylineUL = new PolylineClass();
                     转成IPolyline
                    (pPolylineLR as ISegmentCollection).AddSegment(pLineLR as ISegment, ref oBefore, ref oAfter);
                    (pPolylineUL as ISegmentCollection).AddSegment(pLineUL as ISegment, ref oBefore, ref oAfter);
                    (pPolylineLR as ITopologicalOperator).Simplify();
                    (pPolylineUL as ITopologicalOperator).Simplify();
    
                    IGeometry pGeoLine;
    
                     得到较长的一条中心线
                    if (pPolylineLR.Length > pPolylineUL.Length)
                    {
                        pGeoLine = pPolylineLR as IGeometry;
                    }
                    else
                    {
                        pGeoLine = pPolylineUL as IGeometry;
                    }
    
                    return pGeoLine;
                }
                catch (Exception ex)
                {
                    return null;
                }
            }