Re: Executing a method in a given thread context

Hi Francois,

Before I read this thread, you have several discussion with the community
members alrealdy. To not miss the key point, I want to recap my understand
of this issue.

Based on my understanding, you want to know some best practise of
cross-thread operation in .Net winform and you do not like the pure Win32
p/invoke approach.

Yes, just as you have known, the only recommended way of invoking UI thread
methods from other threads is using Control.Invoke/BeginInvoke methods, I
know you do not want to use them, but these 2 methods are what .Net Winform
provided for this purpose.

If you do not want the component user to take care of the cross-thread
Control.Invoke/BeginInvoke requirement, you'd better refer to
System.Timers.Timer class implementation model. System.Timers.Timer class
normally runs Elapsed event in another non-UI thread, however, it provided
a SynchronizingObject to deal with this. Once SynchronizingObject is set to
certain Control reference, this Elapsed event will be executed in that
control's UI thread without Timer class user aware of. This is very
convinient for the class/component user and I think is what you wanted to
achieve. To achieve this, the Timer class uses MyTimerCallback method to
call the Elapsed event like this:

private void MyTimerCallback(object state)
{
....
try
{
if (this.onIntervalElapsed != null)
{
if ((this.SynchronizingObject != null) &&
this.SynchronizingObject.InvokeRequired)
{

this.SynchronizingObject.BeginInvoke(this.onIntervalElapsed, new object[] {
this, args1 });
}
else
{
this.onIntervalElapsed(this, args1);
}
}
}
catch (Exception)
{
}
...
}
Then in the Elapsed event, the user can write code does not care of the UI
thread operation issue. You may use this design as well.

Additionally, there is rule regarding not use p/invoke. Actually, as you
have found out, .Net winform internally p/invokes Win32 API to complete
must task. So if you want, you may use p/invoke freely. You may encapsulate
all the Win32 API declaration in a class for good maintain ability.

Hope this helps.

Best regards,
Jeffrey Tan
Microsoft Online Community Support
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