判断多边形是否为平行四边形-蒲公英云

判断多边形是否为平行四边形

/// <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;
        }