C#: How to use SHOpenFolderAndSelectItems [duplicate]

Question

Could someone give an example on how to use the shell function SHOpenFolderAndSelectItems from C#? I don't quite get how to use these kind of functions and couldn't find it on pinvoke.net... =/

Say I have three files called

• X:\Pictures\a.jpg
• X:\Pictures\s.jpg
• X:\Pictures\d.jpg

I then want to open up the X:\Pictures folder with a.jpg, s.jpg and d.jpg selected.

Answer 1

As you seem to have asked twice the same question (the other being C#: How to open Windows Explorer windows with a number of files selected that had no answer) I post my solution to both questions I don't know if I should make one a community wiki.

Searching for an answer after a coworker had the issue I found none so I wrote a small class to do this. The code is on Gist and I will paste the current version at the end of this post.

With your sample files, the syntax will be :

 ShowSelectedInExplorer.FilesOrFolders(
  @"X:\Pictures\a.jpg",
  @"X:\Pictures\s.jpg",
  @"X:\Pictures\d.jpg"
  );

There are some limitations to my code compared to the low level API, mainly :

• Selecting on the desktop is not implemented
• The parent directory must be a directory or a drive, so you can't select multiple drives in the My Computer folder for example.

Anyway, here is the ShowSelectedInExplorer class source code :

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;

static class ShowSelectedInExplorer
{
    [Flags]
    internal enum SHCONT : ushort
    {
        SHCONTF_CHECKING_FOR_CHILDREN = 0x0010,
        SHCONTF_FOLDERS = 0x0020,
        SHCONTF_NONFOLDERS = 0x0040,
        SHCONTF_INCLUDEHIDDEN = 0x0080,
        SHCONTF_INIT_ON_FIRST_NEXT = 0x0100,
        SHCONTF_NETPRINTERSRCH = 0x0200,
        SHCONTF_SHAREABLE = 0x0400,
        SHCONTF_STORAGE = 0x0800,
        SHCONTF_NAVIGATION_ENUM = 0x1000,
        SHCONTF_FASTITEMS = 0x2000,
        SHCONTF_FLATLIST = 0x4000,
        SHCONTF_ENABLE_ASYNC = 0x8000
    }

    [ComImport,
    Guid("000214E6-0000-0000-C000-000000000046"),
    InterfaceType(ComInterfaceType.InterfaceIsIUnknown),
    ComConversionLoss]
    internal interface IShellFolder
    {
        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        void ParseDisplayName(IntPtr hwnd, [In, MarshalAs(UnmanagedType.Interface)] IBindCtx pbc, [In, MarshalAs(UnmanagedType.LPWStr)] string pszDisplayName, [Out] out uint pchEaten, [Out] out IntPtr ppidl, [In, Out] ref uint pdwAttributes);
        [PreserveSig]
        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        int EnumObjects([In] IntPtr hwnd, [In] SHCONT grfFlags, [MarshalAs(UnmanagedType.Interface)] out IEnumIDList ppenumIDList);

        [PreserveSig]
        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        int BindToObject([In] IntPtr pidl, [In, MarshalAs(UnmanagedType.Interface)] IBindCtx pbc, [In] ref Guid riid, [Out, MarshalAs(UnmanagedType.Interface)] out IShellFolder ppv);

        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        void BindToStorage([In] ref IntPtr pidl, [In, MarshalAs(UnmanagedType.Interface)] IBindCtx pbc, [In] ref Guid riid, out IntPtr ppv);

        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        void CompareIDs([In] IntPtr lParam, [In] ref IntPtr pidl1, [In] ref IntPtr pidl2);

        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        void CreateViewObject([In] IntPtr hwndOwner, [In] ref Guid riid, out IntPtr ppv);

        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        void GetAttributesOf([In] uint cidl, [In] IntPtr apidl, [In, Out] ref uint rgfInOut);


        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        void GetUIObjectOf([In] IntPtr hwndOwner, [In] uint cidl, [In] IntPtr apidl, [In] ref Guid riid, [In, Out] ref uint rgfReserved, out IntPtr ppv);

        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        void GetDisplayNameOf([In] ref IntPtr pidl, [In] uint uFlags, out IntPtr pName);

        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        void SetNameOf([In] IntPtr hwnd, [In] ref IntPtr pidl, [In, MarshalAs(UnmanagedType.LPWStr)] string pszName, [In] uint uFlags, [Out] IntPtr ppidlOut);
    }

    [ComImport,
    Guid("000214F2-0000-0000-C000-000000000046"),
    InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    internal interface IEnumIDList
    {
        [PreserveSig]
        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        int Next(uint celt, IntPtr rgelt, out uint pceltFetched);

        [PreserveSig]
        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        int Skip([In] uint celt);

        [PreserveSig]
        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        int Reset();

        [PreserveSig]
        [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)]
        int Clone([MarshalAs(UnmanagedType.Interface)] out IEnumIDList ppenum);
    }

    class NativeMethods
    {
        static readonly int pointerSize = Marshal.SizeOf(typeof(IntPtr));

        [DllImport("ole32.dll", EntryPoint = "CreateBindCtx")]
        public static extern int CreateBindCtx_(int reserved, out IBindCtx ppbc);

        public static IBindCtx CreateBindCtx()
        {
            IBindCtx result;
            Marshal.ThrowExceptionForHR(CreateBindCtx_(0, out result));
            return result;
        }

        [DllImport("shell32.dll", EntryPoint = "SHGetDesktopFolder", CharSet = CharSet.Unicode, SetLastError = true)]
        static extern int SHGetDesktopFolder_([MarshalAs(UnmanagedType.Interface)] out IShellFolder ppshf);

        public static IShellFolder SHGetDesktopFolder()
        {
            IShellFolder result;
            Marshal.ThrowExceptionForHR(SHGetDesktopFolder_(out result));
            return result;
        }

        [DllImport("shell32.dll", EntryPoint = "SHOpenFolderAndSelectItems")]
        static extern int SHOpenFolderAndSelectItems_(
            [In] IntPtr pidlFolder, uint cidl, [In, Optional, MarshalAs(UnmanagedType.LPArray)] IntPtr[] apidl, int dwFlags
            );

        public static void SHOpenFolderAndSelectItems(IntPtr pidlFolder, IntPtr[] apidl, int dwFlags)
        {
            var cidl = (apidl != null) ? (uint)apidl.Length : 0U;
            var result = NativeMethods.SHOpenFolderAndSelectItems_(pidlFolder, cidl, apidl, dwFlags);
            Marshal.ThrowExceptionForHR(result);
        }

        [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
        public static extern IntPtr ILCreateFromPath([In, MarshalAs(UnmanagedType.LPWStr)] string pszPath);

        [DllImport("shell32.dll")]
        public static extern void ILFree([In] IntPtr pidl);
    }

    static IntPtr GetShellFolderChildrenRelativePIDL(IShellFolder parentFolder, string displayName)
    {
        var bindCtx = NativeMethods.CreateBindCtx();

        uint pchEaten;
        uint pdwAttributes = 0;
        IntPtr ppidl;
        parentFolder.ParseDisplayName(IntPtr.Zero, null, displayName, out pchEaten, out ppidl, ref pdwAttributes);

        return ppidl;
    }

    static IntPtr PathToAbsolutePIDL(string path)
    {
        var desktopFolder = NativeMethods.SHGetDesktopFolder();
        return GetShellFolderChildrenRelativePIDL(desktopFolder, path);
    }

    static Guid IID_IShellFolder = typeof(IShellFolder).GUID;
    static int pointerSize = Marshal.SizeOf(typeof(IntPtr));

    static IShellFolder PIDLToShellFolder(IShellFolder parent, IntPtr pidl)
    {
        IShellFolder folder;
        var result = parent.BindToObject(pidl, null, ref IID_IShellFolder, out folder);
        Marshal.ThrowExceptionForHR((int)result);
        return folder;
    }

    static IShellFolder PIDLToShellFolder(IntPtr pidl)
    {
        return PIDLToShellFolder(NativeMethods.SHGetDesktopFolder(), pidl);
    }

    static void SHOpenFolderAndSelectItems(IntPtr pidlFolder, IntPtr[] apidl, bool edit)
    {
        NativeMethods.SHOpenFolderAndSelectItems(pidlFolder, apidl, edit ? 1 : 0);
    }

    public static void FileOrFolder(string path, bool edit = false)
    {
        if (path == null) throw new ArgumentNullException("path");

        var pidl = PathToAbsolutePIDL(path);
        try
        {
            SHOpenFolderAndSelectItems(pidl, null, edit);
        }
        finally
        {
            NativeMethods.ILFree(pidl);
        }
    }

    static IEnumerable<FileSystemInfo> PathToFileSystemInfo(IEnumerable<string> paths)
    {
        foreach (var path in paths)
        {
            string fixedPath = path;
            if (fixedPath.EndsWith(Path.DirectorySeparatorChar.ToString()) || fixedPath.EndsWith(Path.AltDirectorySeparatorChar.ToString()))
            {
                fixedPath = fixedPath.Remove(fixedPath.Length - 1);
            }

            if (Directory.Exists(fixedPath)) yield return new DirectoryInfo(fixedPath);
            else if (File.Exists(fixedPath)) yield return new FileInfo(fixedPath);
            else
            {
                throw new FileNotFoundException("The specified file or folder doesn't exists : " + fixedPath, fixedPath);
            }
        }
    }

    public static void FilesOrFolders(string parentDirectory, ICollection<string> filenames)
    {
        if (filenames == null) throw new ArgumentNullException("filenames");
        if (filenames.Count == 0) return;

        var parentPidl = PathToAbsolutePIDL(parentDirectory);
        try
        {
            var parent = PIDLToShellFolder(parentPidl);

            List<IntPtr> filesPidl = new List<IntPtr>(filenames.Count);
            foreach (var filename in filenames)
            {
                filesPidl.Add(GetShellFolderChildrenRelativePIDL(parent, filename));
            }

            try
            {
                SHOpenFolderAndSelectItems(parentPidl, filesPidl.ToArray(), false);
            }
            finally
            {
                foreach (var pidl in filesPidl)
                {
                    NativeMethods.ILFree(pidl);
                }
            }
        }
        finally
        {
            NativeMethods.ILFree(parentPidl);
        }
    }

    public static void FilesOrFolders(params string[] paths)
    {
        FilesOrFolders((IEnumerable<string>)paths);
    }

    public static void FilesOrFolders(IEnumerable<string> paths)
    {
        FilesOrFolders(PathToFileSystemInfo(paths));
    }

    public static void FilesOrFolders(IEnumerable<FileSystemInfo> paths)
    {
        if (paths == null) throw new ArgumentNullException("paths");
        if (paths.Count() == 0) return;

        var explorerWindows = paths.GroupBy(p => Path.GetDirectoryName(p.FullName));

        foreach (var explorerWindowPaths in explorerWindows)
        {
            var parentDirectory = Path.GetDirectoryName(explorerWindowPaths.First().FullName);
            FilesOrFolders(parentDirectory, explorerWindowPaths.Select(fsi => fsi.Name).ToList());
        }
    }
}

Answer 2

Not a 100% answer, but this snippet shows how to select a single item in the explorer from C#.

    private void SelectInFileExplorer(string fullPath)
    {
        if (string.IsNullOrEmpty(fullPath))
            throw new ArgumentNullException("fullPath");

        fullPath = Path.GetFullPath(fullPath);

        IntPtr pidlList = NativeMethods.ILCreateFromPathW(fullPath);
        if (pidlList != IntPtr.Zero)
            try
            {
                // Open parent folder and select item
                Marshal.ThrowExceptionForHR(NativeMethods.SHOpenFolderAndSelectItems(pidlList, 0, IntPtr.Zero, 0));
            }
            finally
            {
                NativeMethods.ILFree(pidlList);
            }
    }

    static class NativeMethods
    {

        [DllImport("shell32.dll", ExactSpelling=true)]
        public static extern void ILFree(IntPtr pidlList);

        [DllImport("shell32.dll", CharSet=CharSet.Unicode, ExactSpelling=true)]
        public static extern IntPtr ILCreateFromPathW(string pszPath);

        [DllImport("shell32.dll", ExactSpelling=true)]
        public static extern int SHOpenFolderAndSelectItems(IntPtr pidlList, uint cild, IntPtr children, uint dwFlags);
    }