Accessing UI components on a background thread.

Frank,

The only methods on a class that derives from Control that are safe to
invoke from any thread are Invoke, BeginInvoke, EndInvoke and CreateGraphics
(if the handle for the control has already been created). Other than that,
anything to access a property/method on the UI has to be called on the UI
thread, through the Invoke method if from another thread (which will marshal
the call to the UI thread).
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"Frank Rizzo" <no**@none.comwrote in message
news:ez**************@TK2MSFTNGP02.phx.gbl...

Hello,

I know that it's a bad thing to update UI components on a background
thread. But is it fairly safe to access them? I want to iterate through
a tree list.

Thanks.

Hi Frank,

Nicholas has provided the best practice rule for you. Actually .Net Winform
controls encapsulate the Win32 native controls. Since the Win32 native
controls are designed as STA COM threading model, we are not allowed to
call it from second thread.

Regarding your task, you may write a helper method which wraps the code to
iterate through your GUI tree list. Then in the second thread, you may use
Control.Invoke or Control.BeginInvoke methods to call this helper method.
This will ensure the thread safety.

Hope this helps.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
==================================================
Get notification to my posts through email? Please refer to
http://msdn.microsoft.com/subscripti...ult.aspx#notif
ications.

Note: The MSDN Managed Newsgroup support offering is for non-urgent issues
where an initial response from the community or a Microsoft Support
Engineer within 1 business day is acceptable. Please note that each follow
up response may take approximately 2 business days as the support
professional working with you may need further investigation to reach the
most efficient resolution. The offering is not appropriate for situations
that require urgent, real-time or phone-based interactions or complex
project analysis and dump analysis issues. Issues of this nature are best
handled working with a dedicated Microsoft Support Engineer by contacting
Microsoft Customer Support Services (CSS) at
http://msdn.microsoft.com/subscripti...t/default.aspx.
==================================================
This posting is provided "AS IS" with no warranties, and confers no rights.

Hi Frank,

Have you reviewed the replies to you? Do they make sense to you? If you
still need any help, please feel free to feedback, thanks.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
==================================================
Get notification to my posts through email? Please refer to
http://msdn.microsoft.com/subscripti...ult.aspx#notif
ications.

Note: The MSDN Managed Newsgroup support offering is for non-urgent issues
where an initial response from the community or a Microsoft Support
Engineer within 1 business day is acceptable. Please note that each follow
up response may take approximately 2 business days as the support
professional working with you may need further investigation to reach the
most efficient resolution. The offering is not appropriate for situations
that require urgent, real-time or phone-based interactions or complex
project analysis and dump analysis issues. Issues of this nature are best
handled working with a dedicated Microsoft Support Engineer by contacting
Microsoft Customer Support Services (CSS) at
http://msdn.microsoft.com/subscripti...t/default.aspx.
==================================================
This posting is provided "AS IS" with no warranties, and confers no rights.

Jeffrey Tan[MSFT] wrote:

Hi Frank,

Have you reviewed the replies to you? Do they make sense to you? If you
still need any help, please feel free to feedback, thanks.

Yes, thank you.

>
Best regards,
Jeffrey Tan
Microsoft Online Community Support
==================================================
Get notification to my posts through email? Please refer to
http://msdn.microsoft.com/subscripti...ult.aspx#notif
ications.

Note: The MSDN Managed Newsgroup support offering is for non-urgent issues
where an initial response from the community or a Microsoft Support
Engineer within 1 business day is acceptable. Please note that each follow
up response may take approximately 2 business days as the support
professional working with you may need further investigation to reach the
most efficient resolution. The offering is not appropriate for situations
that require urgent, real-time or phone-based interactions or complex
project analysis and dump analysis issues. Issues of this nature are best
handled working with a dedicated Microsoft Support Engineer by contacting
Microsoft Customer Support Services (CSS) at
http://msdn.microsoft.com/subscripti...t/default.aspx.
==================================================
This posting is provided "AS IS" with no warranties, and confers no rights.