CODEWITHSUNDEEP
c#winformspowershell
Farrukh Waheed
Farrukh Waheed

Reputation: 2193

Powershell: Unable to interact with Form stored in a .Net Assembly

I'm just trying to learn this thing and in future, wanted to use it in one of my projects.

I have a small Form with a simple Text box, stored in a .Net dll (C#). And here is my class in this dll which contains methods to interact with this Form:

using System;
using System.Collections.Generic;
using System.Text;

namespace ClassLibrary1
{
    public class Class1
    {
        static Form1 dlg = new Form1();

        public static void ShowForm()
        {
            dlg.ShowIcon = true;
            dlg.Show();

        }

        public static void SetText(string MyText)
        {
            dlg.Text = "Form Text ";
            dlg.SetText(MyText);

        }
    }
}

Successfully loaded this form by referencing this dll into another C# application while calling its method i.e.:

private void button1_Click(object sender, EventArgs e)
{
    ClassLibrary1.Class1.ShowForm();
}

And I was able to interact with the form perfectly.

Now loading same in Powershell using:

[Reflection.Assembly]::LoadFile("D:\Playing\ClassLibrary1\ClassLibrary1\bin\Debug\ClassLibrary1.dll")
[ClassLibrary1.Class1]::ShowForm()

Now this is loaded successfully at its default position, but I can't interact with this form i.e. I can't type in its Text Box, neither I can move or even close this form by clicking on its Close (x) button on right corner. Whenever I put my mouse on it, it becomes a HourGlass i.e. waiting for some process .

To verify if form is not hanged, I called SetText at Powershell prompt:

[ClassLibrary1.Class1]::SetText("String from Powershell")

and it worked fine. TextBox received this text properly, but still I can't interact with the form with my mouse.

I feel, I have to manually set its Window Handler i.e. System.Windows.Forms.IWin32Window. But I don't know which Handler and how to achieve this?

Please guide .... Would really appreciate for any alternative tricks.

Upvotes: 2

Views: 1382

Answers (1)

Adriano Repetti
Adriano Repetti

Reputation: 67090

You can't show a form from PowerShell using Form.Show() method because it needs a message pump (and it's not provided by PowerShell host process).

Here what you can do to solve this issue:

  • Use Form.ShowDialog() or Application.Run(), your form will have its own message pump.
  • It'll be modal then you need to run it in another thread. I suggest to use a background thread and BeginInvoke() in your SetText() method.

Here code to do that (I won't change your code too much so I'll keep it as a singleton instance even if this prevents to display form multiple times). Code is just an example (I wouldn't suggest to use Thread Pool for this task) to illustrate the procedure.

public static void ShowForm()
{
    if (dlg != null)
        dlg.BeginInvoke(new MethodInvoker(delegate { dlg.Dispose(); }));

    ThreadPool.QueueUserWorkItem(delegate(object state)
    {
        Application.Run(_dlg = new Form1());
    });
}

public static void SetText(string text)
{
    _dlg.BeginInvoke(new MethodInvoker(delegate { dlg.SetText(text); }));
}

In this way Form1 will be modal in another thread (with its own message pump) and your calling PowerShell thread won't be stopped. Communication between them is still possible via message dispatching (Invoke()/BeginInvoke()).

Please note that SetText() is now asynchronous, to make it synchronous just replace BeginInvoke() with Invoke().

Upvotes: 3

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