数据编辑中 实现要素捕捉

using System.Drawing;  using System.Runtime.InteropServices;  using ESRI.ArcGIS.ADF.BaseClasses;  using ESRI.ArcGIS.ADF.CATIDs;  using ESRI.ArcGIS.Controls;  using System.Windows.Forms;  using ESRI.ArcGIS.Geometry;  using ESRI.ArcGIS.Display;  using ESRI.ArcGIS.esriSystem;    namespace WindowsFormsApplication1.tool  {      /// <summary>      /// Summary description for SnapTool.      /// </summary>      [Guid("192f72b4-5043-45cb-8e1a-743ea964fa97")]      [ClassInterface(ClassInterfaceType.None)]      [ProgId("WindowsFormsApplication1.tool.SnapTool")]      public sealed class SnapTool : BaseTool      {          #region COM Registration Function(s)          [ComRegisterFunction()]          [ComVisible(false)]          static void RegisterFunction(Type registerType)          {              // Required for ArcGIS Component Category Registrar support              ArcGISCategoryRegistration(registerType);                //              // TODO: Add any COM registration code here              //          }            [ComUnregisterFunction()]          [ComVisible(false)]          static void UnregisterFunction(Type registerType)          {              // Required for ArcGIS Component Category Registrar support              ArcGISCategoryUnregistration(registerType);                //              // TODO: Add any COM unregistration code here              //          }           #region ArcGIS Component Category Registrar generated code          /// <summary>          /// Required method for ArcGIS Component Category registration -          /// Do not modify the contents of this method with the code editor.          /// </summary>          private static void ArcGISCategoryRegistration(Type registerType)          {              string regKey = string.Format("HKEY_CLASSES_ROOT\\CLSID\\{{{0}}}", registerType.GUID);              MxCommands.Register(regKey);              ControlsCommands.Register(regKey);          }          /// <summary>          /// Required method for ArcGIS Component Category unregistration -          /// Do not modify the contents of this method with the code editor.          /// </summary>          private static void ArcGISCategoryUnregistration(Type registerType)          {              string regKey = string.Format("HKEY_CLASSES_ROOT\\CLSID\\{{{0}}}", registerType.GUID);              MxCommands.Unregister(regKey);              ControlsCommands.Unregister(regKey);          }           #endregion          #endregion            private IHookHelper m_hookHelper = null;          private IPoint m_snapPt;          private ISnappingEnvironment m_SnapEnv;          private IPointSnapper m_Snapper;          private ISnappingFeedback m_SnapFeedback;          private INewLineFeedback m_feedback;          private ISnappingResult m_snapRst;            public SnapTool()          {              //              // TODO: Define values for the public properties              //              base.m_category = ""; //localizable text               base.m_caption = "";  //localizable text               base.m_message = "This should work in ArcMap/MapControl/PageLayoutControl";  //localizable text              base.m_toolTip = "";  //localizable text              base.m_name = "";   //unique id, non-localizable (e.g. "MyCategory_MyTool")              try              {                  //                  // TODO: change resource name if necessary                  //                  string bitmapResourceName = GetType().Name + ".bmp";                  base.m_bitmap = new Bitmap(GetType(), bitmapResourceName);                  base.m_cursor = new System.Windows.Forms.Cursor(GetType(), GetType().Name + ".cur");              }              catch (Exception ex)              {                  System.Diagnostics.Trace.WriteLine(ex.Message, "Invalid Bitmap");              }          }           #region Overridden Class Methods            /// <summary>          /// Occurs when this tool is created          /// </summary>          /// <param name="hook">Instance of the application</param>          public override void OnCreate(object hook)          {              try              {                  m_hookHelper = new HookHelperClass();                  m_hookHelper.Hook = hook;                  if (m_hookHelper.ActiveView == null)                  {                      m_hookHelper = null;                  }              }              catch              {                  m_hookHelper = null;              }                if (m_hookHelper == null)                  base.m_enabled = false;              else                  base.m_enabled = true;                // TODO:  Add other initialization code          }            /// <summary>          /// Occurs when this tool is clicked          /// </summary>          public override void OnClick()          {              UID uid = new UIDClass();              uid.Value = "{E07B4C52-C894-4558-B804-D4050018D1DA}";              IExtensionManager extMar = (m_hookHelper as IHookHelper2).ExtensionManager;              IExtension ext=extMar.FindExtension(uid);              m_SnapEnv = ext as ISnappingEnvironment;              m_Snapper = m_SnapEnv.PointSnapper;              m_SnapFeedback = new SnappingFeedbackClass();              m_SnapFeedback.Initialize(m_hookHelper.Hook, m_SnapEnv, true);          }            public override void OnMouseDown(int Button, int Shift, int X, int Y)          {              IPoint ppt = m_hookHelper.ActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(X, Y);              if (m_snapPt != null)              {                  ppt = m_snapPt;              }                if (m_feedback != null)              {                  m_feedback = new NewLineFeedbackClass();                  m_feedback.Display = m_hookHelper.ActiveView.ScreenDisplay;                  m_feedback.Start(ppt);              }              else              {                  m_feedback.AddPoint(ppt);              }          }            public override void OnMouseMove(int Button, int Shift, int X, int Y)          {              IPoint ppt = m_hookHelper.ActiveView.ScreenDisplay.DisplayTransformation.ToMapPoint(X, Y);              m_snapPt = ppt;              m_snapRst = m_Snapper.Snap(m_snapPt);              m_SnapFeedback.Update(m_snapRst, 0);              if (m_snapRst != null)              {                  m_snapPt = m_snapRst.Location;              }                if (m_feedback != null)              {                  m_feedback.MoveTo(m_snapPt);              }          }            public override void OnMouseUp(int Button, int Shift, int X, int Y)          {              // TODO:  Add SnapTool.OnMouseUp implementation          }          #endregion      }  }