Wrap an api around a third-party crate

[Roms1383]

Best wishes for 2022 🎉

I wanted to add ambient sounds on my hobby project, so I got a quick PoC using kira which allows to play, mix and transform sounds. I chose kira mainly because it's great, but also because I couldn't find any comparable alternative on pub.dev.

Long story short, I tried a bit but couldn't get anything to compile and I'm wondering if using flutter_rust_bridge to manipulate a kira::manager::AudioManager over FFI is possible, or if this an inappropriate use case for flutter_rust_bridge ?

[fzyzcjy]

Interesting! I guess yes. We already support rich features (have a look at frb_example/pure_dart/rust/api.rs to see tests) and will support more. Even if you find something that does not exist yet, you can always make a PR and I almost always respond quickly!

[Roms1383]

Thanks!
Well TBH I already did, but got stuck.
I'm somehow familiar with Rust but not with FFI and Flutter and got stuck.
My initial idea was to keep the AudioManager around, behind a Mutex with lazy_static and to provide, for a quick test, with something like:

// api.rs

lazy_static! {
    pub static ref AUDIO: Mutex<AudioManager<CpalBackend>> = {
        Mutex::new(
            AudioManager::new(
                CpalBackend::new().expect("audio cpal backend"),
                AudioManagerSettings::default(),
            )
            .expect("create audio manager"),
        )
    };
}

#[repr(u8)]
pub enum Screen {
    Splash,
    Home,
}

#[no_mangle]
pub extern "C" fn play(screen: Screen) {
    let filename = match screen {
        Screen::Home => "../assets/sound/home-screen.mp3",
        Screen::Splash => "../assets/sound/splash-screen.mp3",
    };
    let sound = kira_loaders::load(filename, StaticSoundSettings::default());
    if let Ok(sound) = sound {
        match AUDIO.lock().expect("static audio manager").play(sound) {
            Ok(_) => {}
            Err(_) => {}
        }
    }
}

Also finding a way to return some output so that Flutter app knows if things go right or not.

[fzyzcjy]

#[no_mangle] pub extern "C" no need for that. have a look at tutorial and frb_example/with_flutter and frb_example/pure_rust

[fzyzcjy]

that proto sounds good. I may even put more things in Flutter (to enjoy its fast hot reload): e.g. play(filename: String, other_arguments: Sth), but of course it is your choice

[Roms1383]

yes since this is just my hobby project I experiment but can't spend as much time as I would like to,
so I try to get small things working fast first and iterate afterwards if successful. I'll try to give it another shot after getting back to the examples again, thanks.

[Roms1383]

I ended up making a quick sample repo and opening an issue describing the error I encountered.