How to close kivent app on pause or on stop

[Zain ul Abedeen]

What is the correct way to stop a kivent app if a user a switches the running app or press home button on screen.

I've tried the following but none works. The loaded entities and systems appear to be in the memory and causes memory leak

class Project(App):

    def build(self):

        Window.clearcolor = (0, 0, 0, 1.)

---------------------------------------------------

class Project(App):

    def stop(self):

        return True

---------------------------------------------------

class Project(App):

    def on_pause(self):

        sys.exit(0)

        return True

    def on_resume(self):

        pass

---------------------------------------------------

class Project(App):

    def on_pause(self):

        App.get.running.app().stop()

        return True

    def on_resume(self):

        pass

Thanks!

[Łukasz Mach]

W dniu 11.10.2018 o 13:22, Zain ul Abedeen pisze:

> What is the correct way to stop a kivent app if a user a switches the
> running app or press home button on screen.
> I've tried the following but none works. The loaded entities and systems
> appear to be in the memory and causes memory leak
>

[...]

>
> class Project(App):
>
>     def on_pause(self):
>         sys.exit(0)
>
>         return True
>     def on_resume(self):
>         pass
>

What happends after sys.exit ? Process still hangs out not killed?

regards

Maho

[Zain ul Abedeen]

I get this error:

I/python  (10441):  Exception SystemExit: 0 in 'kivy.core.window._window_sdl2._WindowSDL2Storage.cb_event_filter' ignored

and the app breaks and becomes unresponsive

[Jacob Kovac]

You should not be calling sys.exit, app has a stop command if you want to stop the app.

https://kivy.org/doc/stable/api-kivy.app.html#kivy.app.App.stop

In general to properly do a pause/restart you should be clearing every entity, and getting rid of your gameworld. You would then instantiate a whole new gameworld the same as starting up the app for the first time. Theoretically if you just let your Gameworld get garbage collected everything should clean up properly. However, it might be nice to extend GameWorld to have an explicit deallocate function. This is not implemented at this time. It should be sufficient to just clear the GameWorld's master_buffer as every other system allocates from there. You should definitely be removing all entities and probably all systems. The thing about pause on android is you should never count on unpause happening as the OS could choose to cleanup your app. Pausing should be the exact same behavior as stopping the app entirely and restarting, any thing you want to persist needs to be serialized and deserialized.

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[Zain ul Abedeen]

- How to delete Gameworld, or its master_buffer? (could'nt call self.gameworld.memory_handlers.membuffer.Buffer)

- How to restore Gamworld?

I have elaborated by question in this gist, https://gist.github.com/thegameguy/7d3cf9b27e6dd5915a8b80e1de25e620

Regards

[Zain ul Abedeen]

ok, so its self.gameworld.master_buffer, assuming it gets cleared if its master_buffer = None, 

now if self.gameworld.init(list_of_systems, callback = init_game) is called, it gives the error below

   File "kivent_core\gameworld.pyx", line 271, in kivent_core.gameworld.GameWorld.init_gameworld (kivent_core/gameworld.c:6012)

   File "kivent_core\gameworld.pyx", line 197, in kivent_core.gameworld.GameWorld.ensure_startup (kivent_core/gameworld.c:4592)

 TypeError: 'NoneType' object is not iterable

if i call del self.gameworld before gameworld.init call, I get the following error,

     del self.gameworld

 NotImplementedError: __delete__

 

[Zain ul Abedeen]

if I do self.gameworld = None, i get

ValueError: None is not allowed for TestGame.gameworld

There is not much info about how to manually gc Gameworld. del and None are not working to get rid of the gameworld.

[Jacob Kovac]

It looks like I made a mistake on the implementation here and we actually do need to manually implement delete on the GameWorld.

Would you mind opening a github issue about this?

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[Zain ul Abedeen]

This game engine has so much love in it. I really hope it becomes capable of restarting the game on pause/resume soon.

Regards

[Zain ul Abedeen]

Hey, sorry my bad, on_pause if all running systems are paused and un-paused on_resume function the app has no problems. There is one tiny trick that is to setup a new state which has a list of currently running systems and call this state 'resume'. This state should be setup during on_pause method similar to setting up states at the beginning in the init_game call. and on_resume this state should be set so the currently running systems get un_paused. if the user leaves your app in background for too long than the screen may be blank. Also it is good to call the restore function with a delay of 0.1 in a Clock.schedule_once(self.restore, 0.1).

Check my Gloworld app as a running example. 

Regards

[proze...@gmail.com]

I have tested for hours but the app won't go blank with these settings. Have not been able to reproduce the blank screen error!