Add bottom sheet recipe

[jbw0033]

This commit adds a recipe that demonstrates how to display a navigation destination within a Material ModalBottomSheet.

It introduces BottomSheetSceneStrategy, a SceneStrategy that can be added to a NavDisplay. This strategy checks for specific metadata on a NavEntry to determine if it should be rendered as a bottom sheet.

A new BottomSheetActivity is added to showcase how to use this strategy.

#32

[gemini-code-assist]

Summary of Changes

Hello @jbw0033, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new "recipe" demonstrating how to integrate Material Design ModalBottomSheet components with the Nav3 navigation library. It provides a custom SceneStrategy that allows navigation destinations to be displayed as bottom sheets, enhancing UI flexibility for Android applications.

Highlights

• New BottomSheetSceneStrategy: Introduced BottomSheetSceneStrategy, a custom SceneStrategy for NavDisplay that enables rendering navigation entries as Material ModalBottomSheet components.
• Metadata-driven Bottom Sheet Display: Implemented a metadata-based mechanism (BottomSheetSceneStrategy.bottomSheet()) to designate specific NavEntry instances for display within a bottom sheet.
• New Example Activity: Added BottomSheetActivity as a comprehensive example showcasing the practical application and integration of the new bottom sheet navigation strategy.

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[jbw0033]

@ianhanniballake

[gemini-code-assist]

Code Review

This pull request introduces a new recipe for displaying a navigation destination inside a Material ModalBottomSheet. The implementation is well-structured, adding a BottomSheetSceneStrategy and a corresponding BottomSheetActivity to demonstrate its usage. The code is clear and effectively showcases the feature. I have one minor suggestion to improve adherence to Kotlin's coding conventions.

[alirahimpour89]

What happens if you have a button in the bottomsheet that pop the bottomsheet from the backstack, would that mean no animation? How would you handle that?

[jbw0033]

What happens if you have a button in the bottomsheet that pop the bottomsheet from the backstack, would that mean no animation? How would you handle that?

That is something that would be a good feature request to file here for the material team to address.

[alirahimpour89]

What happens if you have a button in the bottomsheet that pop the bottomsheet from the backstack, would that mean no animation? How would you handle that?

That is something that would be a good feature request to file here for the material team to address.

But is it even possible with the current implementation of nav3 and the scenes? I can think of some ugly hacks but no clean way with the current implementation, that is why I ask here? Maybe I just missed something but I think this receipt show that too because for me the this receipt would not be final without having that animation because it is a pretty common thing if you for example have some kind of menu in the bottom sheet. Because the material 3 bottom sheet has everything it needs to implement it but I don't think the nav3 lib does but I can of course have missed something 🙂

[dturner]

But is it even possible with the current implementation of nav3 and the scenes?

I don't think this is currently possible and have requested this in https://issuetracker.google.com/440558061.

The issue is that OverlayScenes, which BottomSheetScene is, are not wrapped in an AnimatedContent like normal scenes (source) so when you do backStack.removeLast() from inside the bottom sheet, the NavDisplay immediately removes that scene so it disappears rather than being animated out.

A possible workaround (which I haven't tried) would be to programmatically trigger a back event, this would be handled by ModalBottomSheet's back handler and the normal out animation would run.

[lepicekmichal]

I just wrapped the content with this
CompositionLocalProvider(LocalBottomSheetDismiss provides sheetState::hide) {}

Then you use the function instead of your backstack and voila, animation is working, stack is working.