<div>
 
 
Main form -&gt; Form1; 
Second Form -&gt; Form2; 
 
public partial class Form1 
{ 
Form2 _form2; 
 
void ShowSecondFormInThread() 
{ 
System.Threading.Thread t = new System.Threading.Thread ( 
new ThreadStart(delegate 
{ 
_form2 = new Form2(); 
_form2.ShowDialog(); 
} 
)); 
t.ApartmentState = ApartmentState.STA; 
t.Start(); 
} 
} 
 
void CloseSecondForm() 
{ 
form2 .Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Background 
, new EventHandler(delegate 
{ 
&nbsp; &nbsp; &nbsp;_Form2.Close(); 
}), null, new object[] { null }); 
} 
&nbsp; 
&nbsp; 
the closing down routines u can write in the closing event of the second form 

</div>

<div>
Dear Gauthampj, 
Thank you for the precise reply. 
The first half works, with a small modification. I also have a few questions about how it works - see my attached code for the line locators (A, B, C): 
Line &nbsp; (A) new ThreadStart(delegate... what is this construction called? Where can I find out more about why this is used and the logic behind it. 
Line &nbsp;(B)I needed to make the forms visible-false to avodid an exception 
Line &nbsp;(C)I can not find any reference to &quot;apartmentState&quot; in any of my C# books - What is this and where can I find more information? 
The second half will not compile as written because &quot;Dispatcher&quot; is not a known keyword. Please see my code to see if I have reflected you intent correctly. 
Also, I realized that I can start multiple threads. 
&nbsp;- How can I make sure I create only 1? 
&nbsp;- If I do create several, how do I keep track of them and shut down the particular one I want? 
(I can save these for a separate question after we resolve this one - more points for you that way.) 
Thanks, 
JGSchmidt 
&nbsp; 
&nbsp; 
 

<pre><code class="code-10 nolinks" id="code-123636">// ThreadForm1 - start second form in a controllable thread
//
// 20080720 - Jurgen Schmidt
//
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Threading;
using System.Text;
using System.Windows.Forms;
 
namespace ThreadForm1
{
 public partial class Form1 : Form
 {
 private frmLogo _frmLogo;
 
 public Form1()
 {
 InitializeComponent();
 }
 
 // start frmLogo in a thread
 //
 private void btnLogoStart_Click(object sender, EventArgs e)
 {
 Thread t = new Thread( 
 new ThreadStart(delegate // (A) What is happening here ???
 {
 _frmLogo = new frmLogo();
 _frmLogo.Visible = false; // (B)
 _frmLogo.ShowDialog();
 }
 ));
 t.ApartmentState = ApartmentState.STA; // (C) What is happening here ???
 t.Start();
 }
 
 // send message to shut down frmLogo
 //
 private void btnLogoEnd_Click(object sender, EventArgs e)
 {
 _frmLogo.Dispatcher.Invoke(
 DispatcherPriority.Background, new EventHandler(delegate
 {
 _frmLogo.Close();
 }
 ), null, new object[] { null });
 }
 
 
 }
}
</code></pre>
</div>

<div>
Line A -- this creating a delegate with a anonymous method.instead of giveng the method name as we usually do in 1.1 here we can just write the method itself creating an anonymous method. 
Line B -- it must have something to do with the code u have written in frmLogo i gues.. 
Line C-- for GUI components to work the apartment state of the thread that it's working on must be STA 
Dispatcher ketywork is actually only there in 3,5 if u are using 2.0 then _frmLogo.Invoke will do.. 
- How can I make sure I create only 1? 
u need to move the thread variable 't' from method scope to form scope.so when second time the button is clicked u can check for t.IsAlive property which will tell u the thread has already been started. 

</div>

<div>
Dear Gauthampj, 
Thank you again for your reply. 
I am using Visual Studio 2008, C#, and specify .NET 3.5 as the target framework for the project. Dispatcher keyword is still not recognized. The invoke does work though: 
 
_frmLogo.Invoke ( 
&nbsp; &nbsp; new EventHandler(delegate 
&nbsp; &nbsp; { 
&nbsp; &nbsp; &nbsp; &nbsp; _frmLogo.frmLogoClose(); 
&nbsp; &nbsp; } 
) 
); 
However, I do not know why this works and 
&nbsp; &nbsp; &nbsp;_frmLogo.frmLogoClose(); 
by itself does not. (it gets a cross thread exception). How/why does it work? 
&nbsp; 
JGSchmidt 
 
&nbsp; 

</div>

<div>
Thank you for the precision of your answers. This will allow me to move ahead with my project. I suspect I will have additional questions as I expand on what I have learned here.
</div>

<div>
<div class="content wysiwyg-content">
From my main form I would like to start an new form in a separate thread. 
This second form will do its own thing while the main one is continuing with its activities. 
I want to send a message from the main form to the second one when I want it to close. 
I want it to perform a close-down routine &nbsp;so I can not just send it a kill message. 
 
I am somewhat comfortable with background threads from the MSDN examples. 
I am not at all comfortable with delegates. I can cut and paste delegate code but still have only a small clue how it actually works when it comes to cross-thread communication. 
 
I imagine a class with two public methods: ThreadFormStart(parms) and ThreadFormStop(parms). The rest of the implementation should be hidden inside that class. 
 
My initial application is a animation that fades in, hangs around a while and then fades out on command, while the main form is still active. Naturally everything should be thread-safe, etc. 
 
Assume I have never heard of C function pointers. 
 
Thanks for any help.
</div>
</div>

From my main form I would like to start an new form in a separate thread. 
This second form will do its own thing while the main one is continuing with its activities. 
I want to send a message from the main form to the second one when I want it to close. 
I want it to perform a close-down routine  so I can not just send it a kill message. 

I am somewhat comfortable with background threads from the MSDN examples.
I am not at all comfortable with delegates. I can cut and paste delegate code but still have only a small clue how it actually works when it comes to cross-thread communication.

I imagine a class with two public methods: ThreadFormStart(parms) and ThreadFormStop(parms). The rest of the implementation should be hidden inside that class.

My initial application is a animation that fades in, hangs around a while and then fades out on command, while the main form is still active. Naturally everything should be thread-safe, etc.

Assume I have never heard of C function pointers.

Thanks for any help.

Controlling a second form on a separate thread in C#

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.NET Programming

C# is an object-oriented programming language created in conjunction with Microsoft’s .NET framework. Compilation is usually done into the Microsoft Intermediate Language (MSIL), which is then JIT-compiled to native code (and cached) during execution in the Common Language Runtime (CLR).