[2005] Update UI from a thread on another class!!!

[leedo2k]

Hi,

This is one great article. Actually the best I have seen yet. I just have one issue if I may raise it here. I am not sure whether it should be on a spearate thread but if this is not the correct place please move it to wherever you see fit.

Well, I have an issue with invoking my main from to update its UI from an external class rather than the same class like you explained. What I am doing is as follows:

1. Declare a public delegate on the form
2. Declare a public procedure on the form
3. Spawn an instance of my external class and do some work and then update public variables in an external module.
4. When done, I get a handle on the main form using

Application.OpenForms("mainForm")

5. Invoke the UpdateUI procedure in the form like this:

Application.OpenForms("mainForm").Invoke(New UpdateGUIDelegate(AddressOfmainForm.UpdateUI))

The code proceeds with no errors and by stepping through code I can see the textBoxes get assigned the value in the public variables. however, the form text boxes never show the new values!! I tried using application.doevents but no luck. I also tried adding a check on me.invokeRequired at the begining of the UpdateUI form but it always returned FALSE.
Sample code here: Download 52K
Please help..

Thanks confused:

[dolot]

Try a System.threading.thread.sleep(200) after setting the textbox values and see if they appear.

[leedo2k]

Nope, doesn't work.

[dolot]

Did you do it on the thread that is handling the UI?

[bmahler]

I would pass the form instance to the class so that it can update the controls. For instance

Public Property ParentForm() As MainForm
...

Then you can invoke everything from within your class.


Another option is to pass an ISynchronizeInvoker object to the class and use events in your class. When values are set you invoke the events on the ui thread using the ISynchronizeInvoker Object.

[leedo2k]

Did you do it on the thread that is handling the UI?

Yes, I did. But it did not work. Thanks anyway.

[leedo2k]

I would pass the form instance to the class so that it can update the controls. For instance

Public Property ParentForm() As MainForm
...

Then you can invoke everything from within your class.

Yes, that worked. This is abrilliant and at the same time a very clean implementation. Thank very much bmahler