Re: Initializing the GUI from a different thread

On 2022-02-28 08:32, Wuping Xin wrote:
> "Just for my understanding: This means under windows it always needs
> to be the main thread which calls FXApp::run?"
> 
> First thank you for the SUMO project.  I am a user of it.
> 
> -  Yes.  For Fox Toolkit Windows application, the main thread (which
> is where the entry function main() is called),  and the main UI thread
> (which is where MainWindows and other UI elements are created), must
> be the same thread.
> 
> This is because -  dispatchEvent will be invoked in the context of the
> main thread, which maintains the message loop and has all the relevant
> internal dispatchMesage/translateMessage WIN32 call wrapped as part of
> FxApp's methods.
> 
> If you spawn a separate thread, where you call   MainWindow*
> mainwindow=new MainWindow(&application)  -  that separate thread won't
> have WinProc defined/registered thus there won't be any proper message
> loop/dispatching.

As I understand it, it doesn't have anything to do with the WinProc;
rather, when a window is created its is associated with the thread's
event queue [one of which will be created if it didn't exist].

The WinProc is just a subroutine that processes the events; since
we don't assume responsibility for borders, title bar, and other
decorations, we'll use the built-in processing for that.  Other
stuff we intercept and pass along through the FOX system.

But for all intents and purposes, a WinProc is just a routine that
can be executed by any thread [of course I don't recommend it if
other threads may execute same proc on same window, havov is sure
to follow].

The message queue is the important thing.  Its per thread....


   -- JVZ