Save a layer file in a MapControl application
LoadLayerFileCmd.cs
// Copyright 2010 ESRI
// 
// All rights reserved under the copyright laws of the United States
// and applicable international laws, treaties, and conventions.
// 
// You may freely redistribute and use this sample code, with or
// without modification, provided you include the original copyright
// notice and use restrictions.
// 
// See the use restrictions.
// 

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using ESRI.ArcGIS.ADF.BaseClasses;
using ESRI.ArcGIS.ADF.CATIDs;
using ESRI.ArcGIS.Controls;

namespace MapControlSaveLayerFile
{
  /// <summary>
  /// Summary description for LoadLayerFileCmd.
  /// </summary>
  [Guid("c45d8097-5c9b-443c-8859-1663b7b2c540")]
  [ClassInterface(ClassInterfaceType.None)]
  [ProgId("MapControlSaveLayerFile.LoadLayerFileCmd")]
  public sealed class LoadLayerFileCmd : BaseCommand
  {
    #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);
      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);
      ControlsCommands.Unregister(regKey);

    }

    #endregion
    #endregion

    private IHookHelper m_hookHelper;

    public LoadLayerFileCmd()
    {
      base.m_category = ".NET Samples"; 
      base.m_caption = "Load Layer File";
      base.m_message = "Load Layer File from disk";
      base.m_toolTip = "Load Layer File";
      base.m_name = "MapControlSaveLayerFile_LoadLayerFileCmd";   

      try
      {
        //
        // TODO: change bitmap name if necessary
        //
        string bitmapResourceName = GetType().Name + ".bmp";
        base.m_bitmap = new Bitmap(GetType(), bitmapResourceName);
      }
      catch (Exception ex)
      {
        System.Diagnostics.Trace.WriteLine(ex.Message, "Invalid Bitmap");
      }
    }

    #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)
    {
      if (hook == null)
        return;

      if (m_hookHelper == null)
        m_hookHelper = new HookHelperClass();

      m_hookHelper.Hook = hook;

      // TODO:  Add other initialization code
    }

    /// <summary>
    /// Occurs when this command is clicked
    /// </summary>
    public override void OnClick()
    {
      //need to get the layer from the custom-property of the map
      if (null == m_hookHelper)
        return;

      //get the mapControl hook
      object hook = null;
      if (m_hookHelper.Hook is IToolbarControl2)
      {
        hook = ((IToolbarControl2)m_hookHelper.Hook).Buddy;
      }
      else
      {
        hook = m_hookHelper.Hook;
      }

      //get the custom property from which is supposed to be the layer to be saved
      object customProperty = null;
      IMapControl3 mapControl = null;
      if (hook is IMapControl3)
      {
        mapControl = (IMapControl3)hook;
        customProperty = mapControl.CustomProperty;
      }
      else
        return;

      OpenFileDialog ofdlg = new OpenFileDialog();
      ofdlg.Multiselect = true;
      ofdlg.RestoreDirectory = true;
      ofdlg.Title = "Load Layer Files";
      ofdlg.Filter = "Layer File|*.lyr|All Files|*.*";
      DialogResult dr = ofdlg.ShowDialog();
      if (DialogResult.OK == dr)
      {
        string[] files = ofdlg.FileNames;

        foreach (string file in files)
        {
          if (System.IO.File.Exists(file))
            mapControl.AddLayerFromFile(file, 0);
        }
      }
    }

    #endregion
  }
}