Question

I have this problem that My WPF App in its MainWindow:

public partial class MainWindow : Window, ICallbackNotify

this ” ICallbackNotify ” is to communicate with MapInfo COM
and to assure The interactivity between UI & MapInfo

public interface ICallbackNotify : ISynchronizeInvoke
{
    // Method called by MapInfoCallback class when user chooses custom OLE menuitem 
    void OnMenuItemClick(uint id);

    // Method called by MapInfoCallback class when the status bar text changes 
    void OnStatusBarTextChanged(string text);

    // Method called by MapInfoCallback class when window changes
    void OnWindowContentsChanged(uint windowId);
}

The problem is, this code is working just fine in Windows From but when i put it into WPF there is an ERROR msg :

Error   1   'WpfApplication3.MainWindow' does not implement interface member 'System.ComponentModel.ISynchronizeInvoke.InvokeRequired'  c:\users\dragon\documents\visual studio 2010\Projects\WpfApplication3\WpfApplication3\MainWindow.xaml.cs    25  26  WpfApplication3

and i cant figure out why or how to solve this problem

Answer 1

Under the hood Windows Forms and WPF are very different.

ISynchronizeInvoke is a Windows Form concept built upon Win32 API that doesn’t apply to WPF. In WPF, we use the Dispatcher for communicating between threads.

From your question it sounds like what you want to do is host a WinForms COM control inside a WPF application. In order to bridge these two technologies, Microsoft has a WindowsFormHost control that you can use to contain your component. This blog post has a pretty good write up on that. Checkout this MSDN example: https://msdn.microsoft.com/en-us/library/vstudio/ms751761(v=vs.100).aspx

---

Update:

It sounds like the problem you are having isn’t at runtime but during compilation?? Let slow down and be clear:

In Windows Forms, all user controls and windows implement ISynchronizeInvoke. WPF isn’t built on the traditional Win32 WinProc message pump, so they do not implement this interface. If you copy and paste your INotifyCallBack interface and implementation “as is” into the MainWindow.xaml.cs, you will get a compilation error because the base interface ISynchronizeInvoke is not implemented in that class. To bypass the compilation error you will have to implement the ISynchronizeInvoke signature:

public partial class MainWindow : Window, ISynchronizeInvoke
{
   public IAsyncResult BeginInvoke(Delegate method, object[] args)
   {
      throw new NotImplementedException();
   }
   public object EndInvoke(IAsyncResult result)
   {
      throw new NotImplementedException();
   }
   public object Invoke(Delegate method, object[] args)
   {
      throw new NotImplementedException();
   }
   public bool InvokeRequired
   {
      throw new NotImplementedException();
   }
}

But guess what? If you do this, it’s up to you to provide the proper mapping between ISynchronizeInvoke and the WPF Dispatcher. So don’t do this! The above code might compile but it likely won’t work correctly (or at all).

Instead, use the Windows Form Integration capabilities provided by Microsoft to host your control inside a WindowsFormHost control. As you need to implement custom code in your INotifyCallback, you’ll need to put that code into a custom windows forms user control.

All said, you need to follow the direction provided by the article listed above:

• Reference System.Windows.Forms.dll and WindowsFormsIntegration.dll
• Add the appropriate namespaces to your MainWindow.xaml
• Add the WindowsFormsHost as a container into your MainWindow.xaml, and then put your custom control inside of that.

So instead of putting your ICallbackNotify implementation on the WPF MainWindow, put it in a standard Windows Form UserControl:

namespace YourProject {
   using System.ComponentModel;
   using System.Windows.Forms;

   public class MyCustomMapControl : UserControl, ICallbackNotify
   {
       // your custom code goes here
   }
}