C# Signature:
[DllImport("shell32.dll")]
static extern IntPtr SHBrowseForFolder(ref BROWSEINFO lpbi);
VB.NET Signature
<DllImport("shell32.dll", SetLastError:=true, EntryPoint:="SHBrowseForFolderW", CharSet:=CharSet.Unicode)> _
Public Shared Function SHBrowseForFolder(<MarshalAs(UnmanagedType.Struct)>ByRef lpFileOp As BROWSEINFO) As IntPtr
End function
VB Signature
Public Declare Function SHBrowseForFolder Lib "shell32.dll" Alias "SHBrowseForFolderA" _
(prmtypBrowseInfo As BROWSEINFO) As Long
User-Defined Types:
Notes:
None.
Tips & Tricks:
Please add some!
Sample Code:
public class BrowseForFolder
{
// Constants for sending and receiving messages in BrowseCallBackProc
public const int WM_USER = 0x400;
public const int BFFM_INITIALIZED = 1;
public const int BFFM_SELCHANGED = 2;
public const int BFFM_VALIDATEFAILEDA = 3;
public const int BFFM_VALIDATEFAILEDW = 4;
public const int BFFM_IUNKNOWN = 5; // provides IUnknown to client. lParam: IUnknown*
public const int BFFM_SETSTATUSTEXTA = WM_USER + 100;
public const int BFFM_ENABLEOK = WM_USER + 101;
public const int BFFM_SETSELECTIONA = WM_USER + 102;
public const int BFFM_SETSELECTIONW = WM_USER + 103;
public const int BFFM_SETSTATUSTEXTW = WM_USER + 104;
public const int BFFM_SETOKTEXT = WM_USER + 105; // Unicode only
public const int BFFM_SETEXPANDED = WM_USER + 106; // Unicode only
// Browsing for directory.
private uint BIF_RETURNONLYFSDIRS = 0x0001; // For finding a folder to start document searching
private uint BIF_DONTGOBELOWDOMAIN = 0x0002; // For starting the Find Computer
private uint BIF_STATUSTEXT = 0x0004; // Top of the dialog has 2 lines of text for BROWSEINFO.lpszTitle and one line if
// this flag is set. Passing the message BFFM_SETSTATUSTEXTA to the hwnd can set the
// rest of the text. This is not used with BIF_USENEWUI and BROWSEINFO.lpszTitle gets
// all three lines of text.
private uint BIF_RETURNFSANCESTORS = 0x0008;
private uint BIF_EDITBOX = 0x0010; // Add an editbox to the dialog
private uint BIF_VALIDATE = 0x0020; // insist on valid result (or CANCEL)
private uint BIF_NEWDIALOGSTYLE = 0x0040; // Use the new dialog layout with the ability to resize
// Caller needs to call OleInitialize() before using this API
private uint BIF_USENEWUI = 0x0040 + 0x0010; //(BIF_NEWDIALOGSTYLE | BIF_EDITBOX);
private uint BIF_BROWSEINCLUDEURLS = 0x0080; // Allow URLs to be displayed or entered. (Requires BIF_USENEWUI)
private uint BIF_UAHINT = 0x0100; // Add a UA hint to the dialog, in place of the edit box. May not be combined with BIF_EDITBOX
private uint BIF_NONEWFOLDERBUTTON = 0x0200; // Do not add the "New Folder" button to the dialog. Only applicable with BIF_NEWDIALOGSTYLE.
private uint BIF_NOTRANSLATETARGETS = 0x0400; // don't traverse target as shortcut
private uint BIF_BROWSEFORCOMPUTER = 0x1000; // Browsing for Computers.
private uint BIF_BROWSEFORPRINTER = 0x2000;// Browsing for Printers
private uint BIF_BROWSEINCLUDEFILES = 0x4000; // Browsing for Everything
private uint BIF_SHAREABLE = 0x8000; // sharable resources displayed (remote shares, requires BIF_USENEWUI)
[DllImport("shell32.dll")]
static extern IntPtr SHBrowseForFolder(ref BROWSEINFO lpbi);
// Note that the BROWSEINFO object's pszDisplayName only gives you the name of the folder.
// To get the actual path, you need to parse the returned PIDL
[DllImport("shell32.dll", CharSet=CharSet.Unicode)]
// static extern uint SHGetPathFromIDList(IntPtr pidl, [MarshalAs(UnmanagedType.LPWStr)]
//StringBuilder pszPath);
static extern bool SHGetPathFromIDList(IntPtr pidl, IntPtr pszPath);
[DllImport("user32.dll", PreserveSig = true)]
public static extern IntPtr SendMessage(HandleRef hWnd, uint Msg, int wParam, IntPtr lParam);
[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr SendMessage(HandleRef hWnd, int msg, int wParam, string lParam);
private string _initialPath;
public delegate int BrowseCallBackProc(IntPtr hwnd, int msg, IntPtr lp, IntPtr wp);
struct BROWSEINFO
{
public IntPtr hwndOwner;
public IntPtr pidlRoot;
public string pszDisplayName;
public string lpszTitle;
public uint ulFlags;
public BrowseCallBackProc lpfn;
public IntPtr lParam;
public int iImage;
}
public int OnBrowseEvent(IntPtr hWnd, int msg, IntPtr lp, IntPtr lpData)
{
switch(msg)
{
case BFFM_INITIALIZED: // Required to set initialPath
{
//Win32.SendMessage(new HandleRef(null, hWnd), BFFM_SETSELECTIONA, 1, lpData);
// Use BFFM_SETSELECTIONW if passing a Unicode string, i.e. native CLR Strings.
SendMessage(new HandleRef(null, hWnd), BFFM_SETSELECTIONW, 1, _initialPath);
break;
}
case BFFM_SELCHANGED:
{
IntPtr pathPtr = Marshal.AllocHGlobal((int)(260 * Marshal.SystemDefaultCharSize));
if (SHGetPathFromIDList(lp, pathPtr))
SendMessage(new HandleRef(null, hWnd), BFFM_SETSTATUSTEXTW, 0, pathPtr);
Marshal.FreeHGlobal(pathPtr);
break;
}
}
return 0;
}
public string SelectFolder(string caption, string initialPath, IntPtr parentHandle)
{
_initialPath = initialPath;
StringBuilder sb = new StringBuilder(256);
IntPtr bufferAddress = Marshal.AllocHGlobal(256); ;
IntPtr pidl = IntPtr.Zero;
BROWSEINFO bi = new BROWSEINFO();
bi.hwndOwner = parentHandle;
bi.pidlRoot = IntPtr.Zero;
bi.lpszTitle = caption;
bi.ulFlags = BIF_NEWDIALOGSTYLE | BIF_SHAREABLE;
bi.lpfn = new BrowseCallBackProc(OnBrowseEvent);
bi.lParam = IntPtr.Zero;
bi.iImage = 0;
try
{
pidl = SHBrowseForFolder(ref bi);
if (true != SHGetPathFromIDList(pidl, bufferAddress))
{
return null;
}
sb.Append(Marshal.PtrToStringAuto(bufferAddress));
}
finally
{
// Caller is responsible for freeing this memory.
Marshal.FreeCoTaskMem(pidl);
}
return sb.ToString();
}
}
Alternative Managed API:
If using .net version 1.1 or greater, you can use System.Windows.Forms.FolderBrowserDialog instead -- as long as you are only browsing for folders! If you want to browse for computers or printers, the .Net version does not seem to support this.
Note:
You need to be in an STA thread for the BIF_NEWDIALOGSTYLE to work correctly. Use the STAThread attribute on your Main function, or create a new thread and call SetApartmentState before it is started. The default apartment state is MTA so if this isn't working for you, that could be why.
