Show dialog in response to message

[WP]

Disclaimer: I'm new at C# so please be gentle. :-)
I'm writing a simple card game where two players play against each
other through a middle hand they both connect to. In the client (the
player) I read messages from the middle hand in an asynchronous
fashion. I ran into a problem when I tried to implement the player
repsone to the play card message and I need your help.
When the player gets the play card message I want to display a simple
dialog box displaying the cards he or she has available for play.
However, during runtime I get an InvalidOperationException when I
attempt to show the dialog. The more precise error message is, and
here I translate to english: The action between threads is not valid.
The control collected/gathered from another thread than the one it was
created on. Is it because the control (the dialog) tries to use an
object, created by the "main" form, holding the players cards? How
should I solve this in a proper way?

Thanks for reading and thanks for any replies!

- Eric

[Peter Duniho]

On Thu, 13 Mar 2008 17:11:23 -0700, WP <mi********@gmail.comwrote:

[...]
However, during runtime I get an InvalidOperationException when I
attempt to show the dialog. The more precise error message is, and
here I translate to english: The action between threads is not valid.
[...]

The short answer: you need to use Control.Invoke() or
Control.BeginInvoke().

Do a Google search on those method names or on the English language
version of the text for the exception you're seeing.

Pete

[WP]

On 14 Mar, 01:32, "Peter Duniho" <[e-mail]:

On Thu, 13 Mar 2008 17:11:23 -0700, WP <[e-mail]:

[...]
However, during runtime I get an InvalidOperationException when I
attempt to show the dialog. The more precise error message is, and
here I translate to english: The action between threads is not valid.
[...]

The short answer: you need to use Control.Invoke() or
Control.BeginInvoke().

Do a Google search on those method names or on the English language
version of the text for the exception you're seeing.

Pete

Thanks for the quick reply, Pete. After creating dialog and seeing the
exception when calling ShowDialog(), I checked if InvokeRequired was
true and it was false so I didn't think that was the solution. I will
give it another try and post back. Thanks!

- Eric

[Peter Duniho]

On Thu, 13 Mar 2008 17:35:44 -0700, WP <mi********@gmail.comwrote:

Thanks for the quick reply, Pete. After creating dialog and seeing the
exception when calling ShowDialog(), I checked if InvokeRequired was
true and it was false so I didn't think that was the solution. I will
give it another try and post back. Thanks!

How did you check InvokeRequired? Did you use an existing control? Or
did you create a dialog form and then check the property on that form?

Basically, without a concise-but-complete code sample from you, it's
impossible to say exactly what you're doing wrong. But your original
description sounds exactly like the cross-thread exception that's thrown
when you try to access GUI components on the wrong thread, and the
solution for that is calling Invoke() or BeginInvoke().

Pete

[WP]

On 14 Mar, 01:41, "Peter Duniho" <[e-mail]:

On Thu, 13 Mar 2008 17:35:44 -0700, WP <[e-mail]:

Thanks for the quick reply, Pete. After creating dialog and seeing the
exception when calling ShowDialog(), I checked if InvokeRequired was
true and it was false so I didn't think that was the solution. I will
give it another try and post back. Thanks!

How did you check InvokeRequired? Did you use an existing control? Or
did you create a dialog form and then check the property on that form?

I checked it on the dialog after creating it.

>
Basically, without a concise-but-complete code sample from you, it's
impossible to say exactly what you're doing wrong. But your original
description sounds exactly like the cross-thread exception that's thrown
when you try to access GUI components on the wrong thread, and the
solution for that is calling Invoke() or BeginInvoke().

Pete

Here's the part of the messager handler that responds to the play card
message. I must be
misunderstanding something about Invoke, because it didn't work.

try
{
PlayCardDialog dlg = new PlayCardDialog(this.my_cards,
placed_card);

Trace.WriteLine(dlg.InvokeRequired.ToString());

foo_delegate foo = new foo_delegate(dlg.ShowDialog);

this.tracebox.WriteLine(dlg.InvokeRequired.ToStrin g()); // Prints
False

//if (dlg.ShowDialog(this) == DialogResult.OK)
if ((DialogResult)dlg.Invoke(foo, this) == DialogResult.OK)
{
this.tracebox.WriteLine("play card");
}
}
catch (Exception e)
{
this.tracebox.WriteLine(e.ToString());
}

This code is from the function that is called asynchronously when a
message arrives.
this.my_cards is created in the main form when the program is
launched. It's that's what's causing problems? I have no problem
modifying in response to other messages.

Thanks!