Problem with RThread and GUI

[AndySH]

I have some question about RThread.
For example, in my program I create new thread in AppUI class:

iThread.Create(_L("ThreadName"), thread_func, KDefaultStackSize,
				NULL, this);
iThread.Resume();

code of thread_func is:

TInt CTestThreadAppUi::thread_func(TAny* aPtr)
{
    CTrapCleanup* cleanupStack = CTrapCleanup::New();
    
    TRAPD(err, ((CTestThreadAppUi*)aPtr)->run_test())
    
    delete cleanupStack;
    cleanupStack = NULL;
    return err;

}

void CTestThreadAppUi::run_test()
{
    CActiveScheduler* activeScheduler = new(ELeave) CActiveScheduler();
    CleanupStack::PushL(activeScheduler); 
    CActiveScheduler::Install(activeScheduler);
    
    iAppView->AddText( _L("Hello") );
    
    CleanupStack::PopAndDestroy(); //activeScheduler
}

In my AppView I have CEikEdwin and function AddText which adds string to this edwin.

void CTestThreadAppView::AddText(const TDesC& aText)
{
    CPlainText* text = iEdwin->Text();
    text->InsertL( text->DocumentLength(), aText );
    text->InsertL( text->DocumentLength(), CEditableText::ELineBreak );
    iEdwin->HandleTextChangedL();
    iEdwin->SetSelectionL( text->DocumentLength(), text->DocumentLength() );
    iEdwin->SetFocus( ETrue );
    DrawNow();
}

This function works then I call it from AppUI directly, but if I call if from my RThread this function throws panic KERN-EXEC 0 in string

iEdwin->HandleTextChangedL();

In my test there are no any other threads.

[david.caabeiro]

Using gui objects in secondary threads is a bad idea. Do it from your main thread, and also, consider using active objects, unless you're really sure of what you are doing.

[AndySH]

Yes, I agree that it is not good idea, but I wand to know why I receive this panic. Do you have more information than "is a bad idea" ;-)

[david.caabeiro]

CEikEdwin, as related classes, rely on an eikon environment, which is absent in your secondary thread.

[AndySH]

Thanks a lot for reply!
Do you know some method to create eikon environment for the RThread, or it is imossible?

[wizard_hu_]

Do you know some method to create eikon environment for the RThread, or it is imossible?

It is possible, CCoeEnv/CEikonEnv (and CAknEnv) are classes which can be instantiated. Anyway, the result will likely not work.
What do you need exactly?

[david.caabeiro]

You may want to check

http://pushl.com/developers/exeui.html
http://pushl.com/developers/exectrl.html

for some ideas, and do your own tests.. but note that code wasn't tested on 3rd ed, and let me insist you'll run into more trouble than needed..

[AndySH]

Thanks for reply! It's really interesting and useful info for me. Thanks!

[Paul.Todd]

I would be very careful here as the environment already has a GUI on the primary thread.

Also on OS 9.x the method PushL mentions does seem to be very unstable (at least on ESeries)

Use active objects to coordinate requests between threads or even better do not use a thread, there are very few use cases that require it