How to use a FolderBrowserDialog from a WPF application - wpf

Question

I'm trying to use the FolderBrowserDialog from my WPF application - nothing fancy. I don't much care that it has the Windows Forms look to it.
However, when I call ShowDialog, I want to pass the owner window which is an IWin32Window. How do I get this from my WPF control?
Actually, does it matter? If I run this code and use the ShowDialog overload with no parameters it works fine. Under what circumstances do I need to pass the owner window?
Thanks,
Craig

Answer 1

And here's my final version.
public static class MyWpfExtensions
{
public static System.Windows.Forms.IWin32Window GetIWin32Window(this System.Windows.Media.Visual visual)
{
var source = System.Windows.PresentationSource.FromVisual(visual) as System.Windows.Interop.HwndSource;
System.Windows.Forms.IWin32Window win = new OldWindow(source.Handle);
return win;
}
private class OldWindow : System.Windows.Forms.IWin32Window
{
private readonly System.IntPtr _handle;
public OldWindow(System.IntPtr handle)
{
_handle = handle;
}
#region IWin32Window Members
System.IntPtr System.Windows.Forms.IWin32Window.Handle
{
get { return _handle; }
}
#endregion
}
}
And to actually use it:
var dlg = new FolderBrowserDialog();
System.Windows.Forms.DialogResult result = dlg.ShowDialog(this.GetIWin32Window());

Answer 2

If you specify Owner, you will get a Modal dialog over the specified WPF window.
To get WinForms compatible Win32 window create a class implements IWin32Window like this
public class OldWindow : System.Windows.Forms.IWin32Window
{
IntPtr _handle;
public OldWindow(IntPtr handle)
{
_handle = handle;
}
#region IWin32Window Members
IntPtr System.Windows.Forms.IWin32Window.Handle
{
get { return _handle; }
}
#endregion
}
And use an instance of this class at your WinForms
IntPtr mainWindowPtr = new WindowInteropHelper(this).Handle; // 'this' means WPF Window
folderBrowserDialog.ShowDialog(new OldWindow(mainWindowPtr));

Answer 3

I realize this is an old question, but here is an approach which might be slightly more elegant (and may or may not have been available before)...
using System;
using System.Windows;
using System.Windows.Forms;
// ...
/// <summary>
/// Utilities for easier integration with WinForms.
/// </summary>
public static class WinFormsCompatibility {
/// <summary>
/// Gets a handle of the given <paramref name="window"/> and wraps it into <see cref="IWin32Window"/>,
/// so it can be consumed by WinForms code, such as <see cref="FolderBrowserDialog"/>.
/// </summary>
/// <param name="window">
/// The WPF window whose handle to get.
/// </param>
/// <returns>
/// The handle of <paramref name="window"/> is returned as <see cref="IWin32Window.Handle"/>.
/// </returns>
public static IWin32Window GetIWin32Window(this Window window) {
return new Win32Window(new System.Windows.Interop.WindowInteropHelper(window).Handle);
}
/// <summary>
/// Implementation detail of <see cref="GetIWin32Window"/>.
/// </summary>
class Win32Window : IWin32Window { // NOTE: This is System.Windows.Forms.IWin32Window, not System.Windows.Interop.IWin32Window!
public Win32Window(IntPtr handle) {
Handle = handle; // C# 6 "read-only" automatic property.
}
public IntPtr Handle { get; }
}
}
Then, from your WPF window, you can simply...
public partial class MainWindow : Window {
void Button_Click(object sender, RoutedEventArgs e) {
using (var dialog = new FolderBrowserDialog()) {
if (dialog.ShowDialog(this.GetIWin32Window()) == System.Windows.Forms.DialogResult.OK) {
// Use dialog.SelectedPath.
}
}
}
}
Actually, does it matter?
I'm not sure if it matters in this case, but generally, you should tell Windows what is your window hierarchy, so if a parent window is clicked while child window is modal, Windows can provide a visual (and possibly audible) clue to the user.
Also, it ensures the "right" window is on top when there are multiple modal windows (not that I'm advocating such UI design). I've seen UIs designed by a certain multi-billion dollar corporation (which shell remain unnamed), that hanged simply because one modal dialog got "stuck" underneath another, and user had no clue it was even there, let alone how to close it.

Answer 4

OK, figured it out now - thanks to Jobi whose answer was close, but not quite.
From a WPF application, here's my code that works:
First a helper class:
private class OldWindow : System.Windows.Forms.IWin32Window
{
IntPtr _handle;
public OldWindow(IntPtr handle)
{
_handle = handle;
}
#region IWin32Window Members
IntPtr System.Windows.Forms.IWin32Window.Handle
{
get { return _handle; }
}
#endregion
}
Then, to use this:
System.Windows.Forms.FolderBrowserDialog dlg = new FolderBrowserDialog();
HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
System.Windows.Forms.IWin32Window win = new OldWindow(source.Handle);
System.Windows.Forms.DialogResult result = dlg.ShowDialog(win);
I'm sure I can wrap this up better, but basically it works. Yay! :-)

Answer 5

//add a reference to System.Windows.Forms.dll
public partial class MainWindow : Window, System.Windows.Forms.IWin32Window
{
public MainWindow()
{
InitializeComponent();
}
private void button_Click(object sender, RoutedEventArgs e)
{
var fbd = new FolderBrowserDialog();
fbd.ShowDialog(this);
}
IntPtr System.Windows.Forms.IWin32Window.Handle
{
get
{
return ((HwndSource)PresentationSource.FromVisual(this)).Handle;
}
}
}

Answer 6

VB.net translation
Module MyWpfExtensions
Public Function GetIWin32Window(this As Object, visual As System.Windows.Media.Visual) As System.Windows.Forms.IWin32Window
Dim source As System.Windows.Interop.HwndSource = System.Windows.PresentationSource.FromVisual(Visual)
Dim win As System.Windows.Forms.IWin32Window = New OldWindow(source.Handle)
Return win
End Function
Private Class OldWindow
Implements System.Windows.Forms.IWin32Window
Public Sub New(handle As System.IntPtr)
_handle = handle
End Sub
Dim _handle As System.IntPtr
Public ReadOnly Property Handle As IntPtr Implements Forms.IWin32Window.Handle
Get
End Get
End Property
End Class
End Module

Answer 7

Here is a simple method.
System.Windows.Forms.NativeWindow winForm;
public MainWindow()
{
winForm = new System.Windows.Forms.NativeWindow();
winForm.AssignHandle(new WindowInteropHelper(this).Handle);
...
}
public showDialog()
{
dlgFolderBrowser.ShowDialog(winForm);
}

Answer 8

The advantage of passing an owner handle is that the FolderBrowserDialog will not be modal to that window. This prevents the user from interacting with your main application window while the dialog is active.

Answer 9

You should be able to get an IWin32Window by by using PresentationSource.FromVisual and casting the result to HwndSource which implements IWin32Window.
Also in the comments here:

Answer 10

Why not using the built in WindowInteropHelper class (see namespace System.Windows.Interop). This class already impelements the IWin32Window ;)
So you can forget about the "OldWindow class" ... the usage stays the same