Threads, forms, and controls

[Jon Slaughter]

Is this scenario possible?

One has a form, a thread and a control. The thread adds a control to the
form. The form adds handlers to every control added but because the control
is in a different thread the handler might cause an exception.

If this is possible how to I prevent it from happening?

in my form I do

this.ControlRem oved += new
System.Windows. Forms.ControlEv entHandler(this .Control_Remove d);

this.ControlAdd ed += new
System.Windows. Forms.ControlEv entHandler(this .Control_Added) ;



private void Control_Added(o bject sender,
System.Windows. Forms.ControlEv entArgs e)

{

e.Control.LostF ocus += new EventHandler(Co ntrol_LostFocus );

e.Control.Mouse Enter += new EventHandler(Co ntrol_MouseEnte r);

e.Control.Mouse Leave += new EventHandler(Co ntrol_MouseLeav e);

}

private void Control_Removed (object sender,
System.Windows. Forms.ControlEv entArgs e)

{

e.Control.LostF ocus -= new EventHandler(Co ntrol_LostFocus );

e.Control.Mouse Enter -= new EventHandler(Co ntrol_MouseEnte r);

e.Control.Mouse Leave -= new EventHandler(Co ntrol_MouseLeav e);

}





and I'm worried that it could cause issues ;/



Thanks,

Jon

[Laurent Bugnion]

Re: Threads, forms, and controls

Hi,

Jon Slaughter wrote:

Is this scenario possible?
>
One has a form, a thread and a control. The thread adds a control to the
form. The form adds handlers to every control added but because the control
is in a different thread the handler might cause an exception.

You cannot modify the UI elements from another thread than the UI
thread. To pass events to the UI thread from another thread, you must
use the System.Windows. Forms.Control.I nvoke method.

http://msdn2.microsoft.com/en-us/library/system.windows.forms.control.invoke.aspx

To check if you need Invoke or not, use the Control.InvokeR equired property.

HTH
Laurent
--
Laurent Bugnion, GalaSoft
Software engineering: http://www.galasoft-LB.ch
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[Jon Slaughter]

Re: Threads, forms, and controls


"Laurent Bugnion" <galasoft-lb@bluewin.chwr ote in message
news:ekH28$bCHH A.3396@TK2MSFTN GP02.phx.gbl...

Hi,
>
Jon Slaughter wrote:

>Is this scenario possible?
>>
>One has a form, a thread and a control. The thread adds a control to the
>form. The form adds handlers to every control added but because the
>control is in a different thread the handler might cause an exception.

>
You cannot modify the UI elements from another thread than the UI thread.
To pass events to the UI thread from another thread, you must use the
System.Windows. Forms.Control.I nvoke method.

http://msdn2.microsoft.com/en-us/library/system.windows.forms.control.invoke.aspx

>
To check if you need Invoke or not, use the Control.InvokeR equired
property.
>

ok, thanks. This means I don't have to worry about that case.

Jon