Re: Initializing the GUI from a different thread

On 2022-02-28 09:14, Wuping Xin wrote:
> FXApp.cpp, line 1432 (and several other places),  isn't this the
> WndProc registration with the WndClass, as required by Win32 GUI
> programming?
> 
>   wndclass.lpfnWndProc=(WNDPROC) FXApp::wndproc;

Absolutely!  This is the main window proc.  But its fed by
the message queue [getNextEvent() grabs them from there].


> And WndProc in turn, calls app->dispatchEvent, which propels the
> message queue in the current thread context (i.e., the main thread).
> 
> FXival CALLBACK FXApp::wndproc(FXID hwnd,FXuint iMsg,FXuval
> wParam,FXival lParam){
>   return app->dispatchEvent(hwnd,iMsg,wParam,lParam);
>   }
> 
> But of course, each thread has its own message queue that belongs to
> its isolated thread context.   The UI thread spawned separately,
> however, does not have message dispatching needed by the UI  -  all
> messages would end up in a "black hole".

Well, that's how windows is organized.  On Linux/Unix, the event queue
does not belong to any particular thread and events are delivered to
whomever pulls them from the queue. [just not do all threads at once,
please!].

The best we can do, in portable applications, is to have a single
thread manage the GUI.  You can have as many worker threads as you
want, however.  So its a division of labor issue.


    -- JVZ