addListener or similar to OverlayManager

[lea108]

Problem to solve

When working with dialogs implemented as overlays, it would be neat to be able to register a callback on the overlays manager to for example play/pause the game when certain overlays are added.

To do that now you have to make wrappers around add/remove/toggle/setActive and make sure you call those and not Game.overlays directly through your app.

Proposal

Add a addListener() function to OverlayManager, that allow registering a method that will be called whenever the list of active overlays changes.

More information

On one hand it would be nice to get context in the callback, but I think it is better to follow the overall pattern in Flutter to not provide any context to the listener so it is easier in the future to extend cases it gets triggered and leave it up to the user to detect what changed or just re-compute other states based on overlays state.

Other

• Are you interested in working on a PR for this?

[lea108]

Maybe there also should be a setActiveAll() that either takes a map { overlay name => active state }, or just a list of overlays that will be made active, and any overlay not on the list becomes inactive.

Just for the scenario of making bulk updates with only one event trigger.

[lea108]

But it might be a slippery slope. Another option is with FlameGame make it easier to supply your own extended OverlayManager to the constructor to not overload Flame with too much stuff?

[spydon]

I think setActiveAll sounds overkill, but adding listeners could be nice, just make sure it follow the same pattern that we have for other listeners in Flame. I'll assing you to the issue.