[interfacekit] App Activation

From: "Ingo Weinhold" <bonefish@xxxxxxxxxxxxxxx>
To: "Interface Kit" <interfacekit@xxxxxxxxxxxxx>
Date: Sun, 28 Jul 2002 02:15:44 CEST (+0200)
Hi,

I was just implementing BRoster::ActivateApp() and encountered two 
problems. Actually one oddity and one open question.

The weird thing is that (with libbe) my test application class' 
AppActivated() isn't invoked. I create a standard window

        BWindow *window = new BWindow(BRect(100, 100, 200, 200),
                "roster-test", B_TITLED_WINDOW, B_QUIT_ON_WINDOW_CLOSE);
        window->Show();

and the B_APP_ACTIVATED messages appear in MessageReceived(), but 
AppActivated() isn't called. Here are the methods:

        virtual void MessageReceived(BMessage *message)
        {
                printf("TestApp::MessageReceived()\n");
                BMessenger returnAddress(message->ReturnAddress());
                printf("team: %ld\n", returnAddress.Team());
                message->PrintToStream();
                BApplication::MessageReceived(message);
        }

        virtual void AppActivated(bool active)
        {
                printf("TestApp::AppActivated()\n");
                BMessage *message = CurrentMessage();
                message->PrintToStream();
                BMessenger returnAddress(message->ReturnAddress());
                printf("team: %ld\n", returnAddress.Team());
        }

Do I miss anything, or is the R5 implementation buggy? If it is, do we 
mimic that behavior or e.g. call the hook method from 
BApplication::MessageReceived()?

Now to the open question. The BeBook says in the AppActivated() 
description: `This function is called only if the app has an 
"activatable" windowi.e. a non-modal, non-floating window).' Let alone 
my problem described above, this does indeed happen -- i.e. I get the 
message only, if my app has an open window.

The question is, how do we deal with that? This is obviously GUI 
related, but I can verify, that the B_ACTIVATE_APP messages are sent by 
the registrar. My first idea would be, that an application has to 
notify the registrar when the availability of the an "activatable" 
window changes -- this would be the push approach. But as the only 
BRoster method that seems to be related is UpdateActiveApp(team_id 
team), which has no further parameters that could tell the roster about 
anything, I think Be implemented pulling. That is, the roster either 
needs to ask the application itself -- but that does obviously make not 
much sense -- or the app server. In fact the application may not even 
have enough information. E.g. when the active window is closed/
minimized only the app server knows which window to activate next.

I played around a bit and found out, 1) that the app receives its 
B_APP_ACTIVATED messages after the window has got its 
B_WINDOW_ACTIVATED and 2) that when overriding the window's 
DispatchMessage() and not passing B_WINDOW_ACTIVATED messages to the 
super class version, the application doesn't receive B_APP_ACTIVATED 
messages any more.

That makes me believe, that BWindow::DispatchMessage() calls 
BRoster::UpdateActiveApp() which makes the roster have a look, whether 
this application has gained or lost "active" status and send a 
B_APP_ACTIVATED message to the application, if that's the case. 
Nevertheless the roster needs to get this information from somewhere...

Any thoughts?

CU, Ingo
[interfacekit] App Activation

Other related posts:
