.NET Shell Extensions - Shell Property Sheets

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;
using SharpShell.Extensions;
using SharpShell.Interop;

namespace SharpShell
{
    /// <summary>
    /// The ShellExtInitServer is the base class for Shell Extension Servers
    /// that implement IShellExtInit.
    /// </summary>
    public abstract class ShellExtInitServer : SharpShellServer, IShellExtInit
    {
        #region Implementation of IShellExtInit

        /// <summary>
        /// Initializes the shell extension with the parent folder and data object.
        /// </summary>
        /// <param name="pidlFolder">The pidl of the parent folder.</param>
        /// <param name="pDataObj">The data object pointer.</param>
        /// <param name="hKeyProgID">The handle to the key prog id.</param>
        void IShellExtInit.Initialize(IntPtr pidlFolder, IntPtr pDataObj, IntPtr hKeyProgID)
        {
            //  If we have the folder PIDL, we can get the parent folder.
            if (pidlFolder != IntPtr.Zero)
            {
                var stringBuilder = new StringBuilder(260);
                if (User32.SHGetPathFromIDListW(pidlFolder, stringBuilder))
                {
                    //  Set parent folder path.
                    FolderPath = stringBuilder.ToString();
                }
            }

            //  If we have the data object, we can use it to get the selected item paths.
            if (pDataObj != IntPtr.Zero)
            {
                //  Create the IDataObject from the provided pDataObj.
                var dataObject = (System.Runtime.InteropServices.ComTypes.IDataObject) Marshal.GetObjectForIUnknown(pDataObj);

                //  Add the set of files to the selected file paths.
                selectedItemPaths = dataObject.GetFileList();
            }
        }

        #endregion
        
        /// <summary>
        /// The selected item paths.
        /// </summary>
        private List<string> selectedItemPaths = new List<string>();

        /// <summary>
        /// Gets the selected item paths.
        /// </summary>
        public IEnumerable<string> SelectedItemPaths
        {
            get { return selectedItemPaths; }
        }

        /// <summary>
        /// Gets the folder path.
        /// </summary>
        /// <value>
        /// The folder path.
        /// </value>
        public string FolderPath { get; private set; }
    }
}