1 需求说明与实现思路
1.1 需求说明
要素超出图廓错误是不允许的，作业过程需要将这些要素提示出来，供人工检查改正
注：本文设计方法思路，仅适用于矩形图廓的检查，对于不规则图廓，则不适用
1.2 需求实现思路
对于点要素，直接根据图廓坐标确定的矩形范围的角点坐标，判断其是否在图廓范围内
对于线要素，我们将线要素拆解为一组有序的点集，判断点集中的每一个点是否在图廓范围内
对于面要素，获取构成面的所有节点集合，判断点集中的每一个点是否在图廓范围内
基于上述分析，我们判断的关键就是点是否在图廓点确定的范围内的问题
2 源码实现
2.1 点是否在图廓范围内
图廓点集：
源码实现：
- 给定一个点pt，判断其是否在ranges围成的范围内
/// <summary> /// 检查点是否在图廓点确定的数据范围内 /// </summary> /// <param name="pt"></param> /// <param name="ranges"></param> /// <returns></returns> public bool checkPointIsInner(PointF pt, List<PointF> ranges) { if (pt.X < ranges[0].X || pt.X > ranges[2].X) { return false; } if (pt.Y < ranges[0].Y || pt.Y > ranges[2].Y) { return false; } return true; }
2.2 获取点面要素的集合
/// <summary> /// 获取线面要素节点集 /// </summary> /// <param name="fea">要素</param> /// <returns>返回要素节点集合</returns> public List<PointF> getFeatureVerticePts(IFeature fea) { IPointCollection feaPtsColl = fea.Shape as IPointCollection; List<PointF> feaPts = new List<PointF>(); for (int i = 0; i < feaPtsColl.PointCount; i++) { feaPts.Add(new PointF((float)(feaPtsColl.Point[i].X), (float)(feaPtsColl.Point[i].Y))); } return feaPts; }
2.3 获取要素 - IFeatureClass
/// <summary> /// mdb数据库中提取指定名称的要素 /// </summary> /// <param name="wsPath">mdb数据库</param> /// <param name="layerName">要素层名称</param> /// <returns>返回的要素</returns> public IFeatureClass getIFeatureClass(string wsPath, string layerName) { IWorkspaceFactory workspaceFactory = new AccessWorkspaceFactory(); IWorkspace workspace = workspaceFactory.OpenFromFile(wsPath, 0); IFeatureWorkspace featureWorkspace = (IFeatureWorkspace)workspace; //2. 打开要素层 return featureWorkspace.OpenFeatureClass(layerName); }
2.4 判断某个要素是否在节点范围内
此函数的思路是：判断给定IFeature对象是否在outline对象规定的范围内
/// <summary> /// 检查线(面)要素是否超出图廓线范围 /// </summary> /// <param name="outline">图廓线要素</param> /// <param name="feaLine">线(面)要素</param> /// <returns>false表示在图廓内部，true表示在图廓外边</returns> public bool lineIsBeyondOutline(IFeature outline, IFeature feaLine) { List<PointF> outlinePts = getFeatureVerticePts(outline); List<PointF> feaLinePts = getFeatureVerticePts(feaLine); for (int i = 0; i < feaLinePts.Count; i++) { if (!checkPointIsInner(feaLinePts[i], outlinePts)) { return true; } } return false; }
2.5 对图层进行检查
/// <summary> /// 检查点图层 /// </summary> /// <param name="wsPath">数据库名称</param> /// <param name="layerName">图层名称</param> public void checkPointsLayer(string wsPath, string layerName) { IFeatureClass pFeaterClass = getIFeatureClass(wsPath, layerName) IFeature outline = getOutlineFromCPTL(wsPath); //3. 获取投影信息 IGeoDataset geoDatabase = pFeaterClass as IGeoDataset; //4. 查询所有要素 string where = ""; IQueryFilter filter = new QueryFilterClass(); filter.WhereClause = where; //5.定义查询游标并循环迭代 IFeatureCursor pFeatcursor = pFeaterClass.Search(filter, false); IFeature pFeature = pFeatcursor.NextFeature(); //6. 运算结果存储 List<IFeature> errLists = new List<IFeature>(); while (pFeature != null) { if (lineIsBeyondOutline(outline, pFeature)) { errLists.Add(pFeature); } pFeature = pFeatcursor.NextFeature(); } ExportPtsToShapefile(wsPath, errLists, layerName, esriGeometryType.esriGeometryPoint); }
