Select either a file or folder from the same dialog in .NET


Is there an "easy" way to select either a file OR a folder from the same dialog?

In many apps I create I allow for both files or folders as input. Until now i always end up creating a switch to toggle between file or folder selection dialogs or stick with drag-and-drop functionality only.

Since this seems such a basic thing i would imagine this has been created before, but googling does not result in much information. So it looks like i would need to start from scratch and create a custom selection Dialog, but I rather not introduce any problems by reinventing the wheel for such a trivial task.

Anybody any tips or existing solutions?

To keep the UI consistent it would be nice if it is possible to extend the OpenFileDialog (or the FolderBrowserDialog).

6/24/2009 5:21:08 PM

Accepted Answer

Technically, it is possible. The shell dialog used by FolderBrowseDialog has the ability to return both files and folders. Unfortunately, that capability isn't exposed in .NET. Not even reflection can poke the required option flag.

To make it work, you'd have to P/Invoke SHBrowseForFolder() with the BIF_BROWSEINCLUDEFILES flag turned on in BROWSEINFO.ulFlags (value = 0x4000). The P/Invoke is gritty, it is best to copy and paste the code from another source or the FolderBrowseDialog class itself with Reflector's help.

1/10/2009 3:01:58 PM

Based on the above tips I found some working code that uses the standard Folder Browser dialog at the following location:

The Class for the extended Folder Browser Dialog

Imports System   
Imports System.Text   
Imports System.Windows.Forms   
Imports System.Runtime.InteropServices   

Public Class DirectoryDialog 
    Public Structure BROWSEINFO 
        Public hWndOwner As IntPtr 
        Public pIDLRoot As Integer 
        Public pszDisplayName As String 
        Public lpszTitle As String 
        Public ulFlags As Integer 
        Public lpfnCallback As Integer 
        Public lParam As Integer 
        Public iImage As Integer 
    End Structure 

    Const MAX_PATH As Integer = 260

    Public Enum BrowseForTypes As Integer 
        Computers = 4096 
        Directories = 1 
        FilesAndDirectories = 16384 
        FileSystemAncestors = 8 
    End Enum 

    Declare Function CoTaskMemFree Lib "ole32" Alias "CoTaskMemFree" (ByVal hMem As IntPtr) As Integer 
    Declare Function lstrcat Lib "kernel32" Alias "lstrcat" (ByVal lpString1 As String, ByVal lpString2 As String) As IntPtr 
    Declare Function SHBrowseForFolder Lib "shell32" Alias "SHBrowseForFolder" (ByRef lpbi As BROWSEINFO) As IntPtr 
    Declare Function SHGetPathFromIDList Lib "shell32" Alias "SHGetPathFromIDList" (ByVal pidList As IntPtr, ByVal lpBuffer As StringBuilder) As Integer 
    Protected Function RunDialog(ByVal hWndOwner As IntPtr) As Boolean 

        Dim udtBI As BROWSEINFO = New BROWSEINFO() 
        Dim lpIDList As IntPtr 
        Dim hTitle As GCHandle = GCHandle.Alloc(Title, GCHandleType.Pinned) 
        udtBI.hWndOwner = hWndOwner 
        udtBI.lpszTitle = Title 
        udtBI.ulFlags = BrowseFor 
        Dim buffer As StringBuilder = New StringBuilder(MAX_PATH) 
        buffer.Length = MAX_PATH 
        udtBI.pszDisplayName = buffer.ToString() 
        lpIDList = SHBrowseForFolder(udtBI) 
        If lpIDList.ToInt64() <> 0 Then 
            If BrowseFor = BrowseForTypes.Computers Then 
                m_Selected = udtBI.pszDisplayName.Trim() 
                Dim path As StringBuilder = New StringBuilder(MAX_PATH) 
                SHGetPathFromIDList(lpIDList, path) 
                m_Selected = path.ToString() 
            End If 
            Return False 
        End If 
        Return True 
    End Function 

    Public Function ShowDialog() As DialogResult 
        Return ShowDialog(Nothing) 
    End Function 

    Public Function ShowDialog(ByVal owner As IWin32Window) As DialogResult 
        Dim handle As IntPtr 
        If Not owner Is Nothing Then 
            handle = owner.Handle 
            handle = IntPtr.Zero 
        End If 
        If RunDialog(handle) Then 
            Return DialogResult.OK 
            Return DialogResult.Cancel 
        End If 
    End Function 

    Public Property Title() As String 
            Return m_Title 
        End Get 
        Set(ByVal Value As String) 
            If Value Is DBNull.Value Then 
                Throw New ArgumentNullException() 
            End If 
            m_Title = Value 
        End Set 
    End Property

    Public ReadOnly Property Selected() As String 
            Return m_Selected 
        End Get 
    End Property 

    Public Property BrowseFor() As BrowseForTypes
            Return m_BrowseFor 
        End Get 
        Set(ByVal Value As BrowseForTypes) 
            m_BrowseFor = Value 
        End Set 
    End Property 

    Private m_BrowseFor As BrowseForTypes = BrowseForTypes.Directories 
    Private m_Title As String = "" 
    Private m_Selected As String = "" 

    Public Sub New() 
    End Sub
End Class 

The code to implement the extended dialog

Sub Button1Click(ByVal sender As Object, ByVal e As EventArgs)
    Dim frmd As DirectoryDialog = New DirectoryDialog()
    ' frmd.BrowseFor = DirectoryDialog.BrowseForTypes.Directories   
    ' frmd.BrowseFor = DirectoryDialog.BrowseForTypes.Computers   
    frmd.BrowseFor = DirectoryDialog.BrowseForTypes.FilesAndDirectories   
    frmd.Title = "Select a file or a folder"    
    If frmd.ShowDialog(Me) = DialogResult.OK Then   
    End If   
End Sub

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