如何將一個圖層上的一條線的ToPoint和FromPoint添加到另一個圖層/要素類

Question

我有一個道路圖層。 我需要將點添加到其他道路相交的點層。 如何將這些點添加到現有的點層。

在手中，我有線圖層，線要素/來源點和點圖層。 我只需要一個關於如何在點圖層中創建點的指針。

我正在使用C＃

謝謝。

Answer 1

下面的代碼展示了通過使用擴展方法來實現這一點的方法。 ArcObjects API經常被批評爲具有太多可能的接口，導致可讀性較差的代碼。我相信擴展方法可以解決許多這些問題。缺點是閱讀代碼的人無法區分作爲API一部分的擴展方法和方法。

我不確定問題的背景，但是如果您爲街道交叉點創建點，則可以考慮使用不同的點哈希函數。這將允許道路交叉點在多個點交叉的地方由單點表示。這將與地圖拓撲中使用的集羣容差類似。

我還沒有真正掌握一個很好的繼承方法來爲自定義異常調用基礎構造函數。任何建議，將不勝感激。

using System; 
using System.Runtime.InteropServices; 
using ESRI.ArcGIS.ADF.BaseClasses; 
using ESRI.ArcGIS.Framework; 
using System.Windows.Forms; 
using ESRI.ArcGIS.Geometry; 
using ESRI.ArcGIS.ArcMapUI; 
using ESRI.ArcGIS.Geodatabase; 
using ESRI.ArcGIS.Carto; 
using System.Collections.Generic; 
using ESRI.ArcGIS.Editor; 

namespace IGG.SurveyTools 
{ 
    /// <summary> 
    /// Summary description for TestCommand. 
    /// </summary> 
    [ProgId("IGG.SurveyTools.TestCommand")] 
    public sealed class TestCommand : BaseCommand 
    { 
     private IEditor m_Editor; 
     public TestCommand() 
     { 
      // 
      // TODO: Define values for the public properties 
      // 
      base.m_category = ""; //localizable text 
      base.m_caption = "Add End points"; //localizable text 
      base.m_message = ""; //localizable text 
      base.m_toolTip = ""; //localizable text 
      base.m_name = ""; //unique id, non-localizable (e.g. "MyCategory_MyCommand") 
     } 

     #region Overriden Class Methods 

     /// <summary> 
     /// Occurs when this command is created 
     /// </summary> 
     /// <param name="hook">Instance of the application</param> 
     public override void OnCreate(object hook) 
     { 
      IApplication app = hook as IApplication; 
      if (app == null) 
       return; 
      m_Editor = app.FindExtensionByName("ESRI Object Editor") as IEditor; 
     } 
     public override bool Enabled 
     { 
      get 
      { 
       return (m_Editor != null && m_Editor.EditState == esriEditState.esriStateEditing); 
      } 
     } 
     public override void OnClick() 
     { 
      try 
      { 
       string fmt = "{0},{1}"; 

       IMxDocument mxDoc = (IMxDocument)m_Editor.Parent.Document; 

       IFeatureLayer polylineLayer = mxDoc.FocusMap.FindFLayer("My Polylines"); 
       IFeatureLayer pointLayer = mxDoc.FocusMap.FindFLayer("My Points"); 
       if(((IDataset)pointLayer.FeatureClass).Workspace != m_Editor.EditWorkspace) 
       { 
        MessageBox.Show(new Win32Win(m_Editor), "Points layer is not being edited"); 
        return; 
       } 
       Dictionary<string, IPoint> endPoints = polylineLayer.GetEndPoints(fmt); 
       if (endPoints.Count == 0) 
       { 
        MessageBox.Show("no end points found"); 
        return; 
       } 
       Dictionary<string,IPoint> existingPoints = pointLayer.GetPoints(fmt); 
       Dictionary<string,IPoint> newPoints = endPoints.Subtract(existingPoints); 
       if(newPoints.Count == 0) 
       { 
        MessageBox.Show(new Win32Win(m_Editor.Parent),"all endpoints are present in pointslayer"); 
        return; 
       } 

       m_Editor.StartOperation(); 
       try 
       { 
        pointLayer.FeatureClass.PutPoints(newPoints.Values); 
        m_Editor.StopOperation(String.Format("Added {0} new endpoints", newPoints.Count)); 
        ((IActiveView)m_Editor.Map).Refresh(); 
       } 
       catch(Exception ex) 
       { 
        m_Editor.AbortOperation(); 
       } 
      } 
      catch (Exception ex) 
      { 
       MessageBox.Show(new Win32Win(m_Editor), ex.Message + Environment.NewLine + ex.StackTrace); 
      } 
     }   
     #endregion 

    } 

    public class Win32Win : IWin32Window 
    { 
     private IntPtr m_handle; 
     public Win32Win(IApplication app) { m_handle = new IntPtr(app.hWnd); } 
     public IntPtr Handle { get { return m_handle; } } 
     public Win32Win(int hwnd) { m_handle = new IntPtr(hwnd); } 
     public Win32Win(IEditor editor) { m_handle = new IntPtr(editor.Parent.hWnd); } 
    } 

    public class LayerNotFoundException : Exception 
    { 
     public LayerNotFoundException(string lyrName) 
      : base("Layer not found: " + lyrName) 
     { 
     } 
    } 

    public class FeatureLayerNotFoundException : LayerNotFoundException 
    { 
     public FeatureLayerNotFoundException(string lyrName) 
      : base(lyrName) 
     { 
     } 
    } 

    public static class MyExtensions 
    { 
     public static void PutPoints(this IFeatureClass fc, IEnumerable<IPoint> pnts) 
     { 
      IFeatureCursor fCur = fc.Insert(false); 
      IFeatureBuffer buff = fc.CreateFeatureBuffer(); 
      foreach (IPoint pnt in pnts) 
      { 
       buff.Shape = pnt; 
       fCur.InsertFeature(buff); 
      } 
      fCur.Flush(); 
      System.Runtime.InteropServices.Marshal.FinalReleaseComObject(fCur); 
     } 

     /// <summary> 
     /// returns first layer in map with case-insensitive name 
     /// </summary> 
     /// <param name="map"></param> 
     /// <param name="name"></param> 
     /// <returns></returns> 
     public static ILayer FindLayer(this IMap map, string name) 
     { 
      if (map.LayerCount == 0) 
       throw new LayerNotFoundException(name); 
      IEnumLayer enumLayer = map.get_Layers(null, true); 
      ILayer layer; 
      while ((layer = enumLayer.Next()) != null) 
      { 
       if (layer.Name.Trim().ToUpper() == name.Trim().ToUpper()) 
        return layer; 
      } 
      throw new LayerNotFoundException(name); 
     } 

     public static IFeatureLayer FindFLayer(this IMap map, string name) 
     { 
      IFeatureLayer fLayer = map.FindLayer(name) as IFeatureLayer; 
      if (fLayer == null) 
       throw new FeatureLayerNotFoundException(name); 
      return fLayer; 
     } 

     public static Dictionary<string, IPoint> GetPoints(this IFeatureLayer fLayer, string fmt) 
     { 
      if (fLayer.FeatureClass == null 
       || fLayer.FeatureClass.ShapeType != esriGeometryType.esriGeometryPoint) 
       throw new Exception("bad point layer: " + fLayer.Name); 

      Dictionary<string, IPoint> outDict = new Dictionary<string, IPoint>(); 
      IFeatureCursor fCur = fLayer.FeatureClass.Search(null, false); 
      IFeature feat; 
      while ((feat = fCur.NextFeature()) != null) 
      { 
       outDict.AddPoint((IPoint)feat.ShapeCopy,fmt); 
      } 
      System.Runtime.InteropServices.Marshal.FinalReleaseComObject(fCur); 
      return outDict; 
     } 

     public static Dictionary<string, IPoint> GetEndPoints(this IFeatureLayer fLayer, string fmt) 
     { 
      if (fLayer.FeatureClass == null 
       || fLayer.FeatureClass.ShapeType != esriGeometryType.esriGeometryPolyline) 
       throw new Exception("bad polyline layer: " + fLayer.Name); 

      Dictionary<string, IPoint> outDict = new Dictionary<string, IPoint>(); 
      IFeatureCursor fCur = fLayer.FeatureClass.Search(null, false); 
      IFeature feat; 
      while ((feat = fCur.NextFeature()) != null) 
      { 
       IPolyline polyline = (IPolyline)feat.ShapeCopy; 
       if (polyline == null || polyline.IsEmpty) 
        continue; 
       outDict.AddPoint(polyline.FromPoint,fmt); 
       outDict.AddPoint(polyline.ToPoint,fmt); 
      } 
      System.Runtime.InteropServices.Marshal.FinalReleaseComObject(fCur); 
      return outDict; 
     } 
     public static string Hash(this IPoint pnt, string fmt) 
     { 
      // use different formatting options to do quick and dirty clustering 
      return String.Format(fmt, pnt.X, pnt.Y); 
     } 

     public static void AddPoint(this Dictionary<string,IPoint> dict ,IPoint pnt, string fmt) 
     { 
      string hash = pnt.Hash(fmt); 
      if (!dict.ContainsKey(hash)) 
       dict.Add(hash, pnt); 
     } 
     public static Dictionary<string, IPoint> Subtract(this Dictionary<string, IPoint> inDict, Dictionary<string, IPoint> otherDict) 
     { 
      Dictionary<string, IPoint> outDict = new Dictionary<string, IPoint>(); 
      foreach (KeyValuePair<string, IPoint> kvp in inDict) 
      { 
       if (!otherDict.ContainsKey(kvp.Key)) 
        outDict.Add(kvp.Key, kvp.Value); 
      } 
      return outDict; 
     } 
    } 
}