判断多边形是否为平行四边形

深藏阁楼爱情的钟 2022-08-07 01:33 208阅读 0赞

/// <summary>
            /// 判断多边形是否为平行四边形
            /// </summary>
            /// <param name="pPolygon">多边形</param>
            /// <returns></returns>
            public bool IsParallelogram(IPolygon pPolygon)
            {
                bool bResult = false;
    
                if (pPolygon == null)
                {
                    return false;
                }
    
                try
                {
                    IPointCollection pPointCol = pPolygon as IPointCollection;
                     这里判断5个点，是因为AE中绘制多边形是从起点开始，再绘制到起点结束，为一个封闭的图形
                    if (pPointCol.PointCount != 5)
                    {
                        return false;
                    }
    
                    IPoint pFstPt = null;
                    IPoint pSecPt = null;
                    IPoint pTrdPt = null;
                    IPoint pForPt = null;
                     这些点是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);
    
                    ILine pFstLine = new LineClass();
                    ILine pSecLine = new LineClass();
                    ILine pTrdLine = new LineClass();
                    ILine pForLine = new LineClass();
                     获得四边形的四条边
                    pFstLine.PutCoords(pFstPt, pSecPt);
                    pSecLine.PutCoords(pSecPt, pTrdPt);
                    pTrdLine.PutCoords(pTrdPt, pForPt);
                    pForLine.PutCoords(pForPt, pFstPt);
    
                     对边相等则是平行四边形
                    if (pFstLine.Length == pTrdLine.Length && pSecLine.Length == pForLine.Length)
                    {
                        bResult = true;
                    }
    
                }
                catch (Exception ex)
                {
                    bResult = false;
                }
                return bResult;
            }