A Custom UITypeEditor for Activity Properties
As with many other technologies, the design time experience in Windows Workflow Foundation uses many of the same extensibility mechanisms found in other designers (such as the Windows Forms designer). One of those is the hability to provide custom type editors for properties by creating an UITypeEditor-derived class and then associating it with the property via the [Editor] attribute.
Here's a sample UITypeEditor that will present an OpenFileDialog to choose a file name as the property value:
//
// FileSelectorTypeEditor.cs
//
// Author:
// Tomas Restrepo (tomasr@mvps.org)
//
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
using System.Drawing.Design;
using System.IO;
using System.Text;
using System.Windows.Forms;
using System.Windows.Forms.Design;
namespace Winterdom.Design.TypeEditors
{
/// <summary>
/// Customer UITypeEditor that pops up a
/// file selector dialog
/// </summary>
public class FileSelectorTypeEditor : UITypeEditor
{
public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)
{
if ( context == null || context.Instance == null )
return base.GetEditStyle(context);
return UITypeEditorEditStyle.Modal;
}
public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
{
IWindowsFormsEditorService editorService;
if ( context == null || context.Instance == null || provider == null )
return value;
try
{
// get the editor service, just like in windows forms
editorService = (IWindowsFormsEditorService)
provider.GetService(typeof(IWindowsFormsEditorService));
OpenFileDialog dlg = new OpenFileDialog();
dlg.Filter = "All Files (*.*)|*.*";
dlg.CheckFileExists = true;
string filename = (string)value;
if ( !File.Exists(filename) )
filename = null;
dlg.FileName = filename;
using ( dlg )
{
DialogResult res = dlg.ShowDialog();
if ( res == DialogResult.OK )
{
filename = dlg.FileName;
}
}
return filename;
} finally
{
editorService = null;
}
}
} // class FileSelectorTypeEditor
} // namespace Winterdom.Design.TypeEditors
You can then easily associate it with a property like this:
[Editor(typeof(FileSelectorTypeEditor), typeof(UITypeEditor))]
public string Filename
{
get { return _filename; }
set { _filename = value; }
}
One thing to watch out for, though, is that at least with the July CTP of WinFX, WF will completely ignore your custom UITypeEditor if it is defined in the same assembly as the activity using it. Don't know why, but make sure you define it in a separate assembly you reference, and it should work OK.
I try this but it doesn’t work. I created a separate class library, compiled it to .NET assembly (Dll file) then reference it in windows Form application. The program runs without error, the dialog does not show.
Please can you explain it again.
Again, i converted it to VB.NET. May be because i used Overloads instead of overrides. Vb wont let me overrides it GetEditStyle and EditValue then i switched it to overloads method
Can you comment on that please
kenny
Thank’s a lot!
It works
[...] I remembered that I’ve done it several times, but hey 2.5 years is a looong time in which to forget stuff like this.. Luckily I found a real nice example on how to do this in this post by Tomas Restrepo: http://winterdom.com/2006/08/acustomuitypeeditorforactivityproperties/comment-page-1. [...]
Good Solution!
Thanks
‘VB.NET Code
Imports System
Imports System.ComponentModel
Imports System.Drawing.Design
Imports System.IO
Imports System.Windows.Forms
Imports System.Windows.Forms.Design
Public Class SelectorTypeFileDialog
Public Class FileSelectorTypeEditor
Inherits UITypeEditor
Public Overloads Overrides Function GetEditStyle(ByVal context As ITypeDescriptorContext) As UITypeEditorEditStyle
If context Is Nothing OrElse context.Instance Is Nothing Then
Return MyBase.GetEditStyle(context)
End If
Return UITypeEditorEditStyle.Modal
End Function
Public Overloads Overrides Function EditValue(ByVal context As ITypeDescriptorContext, ByVal provider As IServiceProvider, ByVal value As Object) As Object
Dim editorService As IWindowsFormsEditorService
If context Is Nothing OrElse context.Instance Is Nothing OrElse provider Is Nothing Then
Return value
End If
Try
‘ get the editor service, just like in windows forms
editorService = DirectCast(provider.GetService(GetType(IWindowsFormsEditorService)), IWindowsFormsEditorService)
Dim dlg As New OpenFileDialog()
dlg.Filter = “All Files (*.*)|*.*”
dlg.CheckFileExists = True
Dim filename As String = DirectCast(value, String)
If Not File.Exists(filename) Then
filename = Nothing
End If
dlg.FileName = filename
Using dlg
Dim res As DialogResult = dlg.ShowDialog()
If res = DialogResult.OK Then
filename = dlg.FileName
End If
End Using
Return filename
Finally
editorService = Nothing
End Try
End Function
End Class
End Class