Hi all :android-wave: , I have a code like this, `...

# compose-android

[Abhimanyu]

Hi all 👋 ,
I have a code like this,

@Composable
fun ScreenComposable() {
  val handleUri = { uri: Uri ->
    // Some code
  }
  val openDocumentResultLauncher: ManagedActivityResultLauncher<Array<String>, Uri?> = rememberLauncherForActivityResult(
    contract = ActivityResultContracts.OpenDocument(),
  ) { uri ->
    uri?.let {
      handleUri()
    }
  }

  // openDocumentResultLauncher is used like this,
  val object = remember {
    SomeClass(
      openDocument = {
        openDocumentResultLauncher.launch(arrayOf(MimeTypeConstants.JSON))
      },
    )
  }
}

In this code, handleUri has to be defined before openDocumentResultLauncher .
Can I rewrite this code in a way that handleUri is passed as a parameter (dependency) to openDocumentResultLauncher .
openDocument in SomeClass will provide the code for handleUri .

[Ian Lake]

Caleb's approach doesn't work at all - extras you pass to the other activity aren't sent back to you to parse. Even then, there's no way to have a Serializable that has a lambda

[Ian Lake]

If you look at the implementation of rememberLauncherForActivityResult, you'll see a few important things:
1. You need a unique key that survives process death and recreation (the rememberSaveable { UUID.randomUUID().toString() } part) - that's how this actually reconnects consistently
2. Getting the ActivityResultRegistry using the LocalActivityResultRegistryOwner
3. Calling register (which is what requires your handleUri) and unregister in a DisposableEffect such that the launcher only exists as long as it exists in composition
Technically, those are all pieces you can do yourself, in any place you want. However, I don't think you can do all of that within the remember of SomeClass

[Abhimanyu]

Hi Ian,
Thanks for answering, but I am not clear on what to do or if this is possible.

What I want is to move handleUri inside SomeClass .

Currently, createDocument callback of SomeClass will expose the handler to the parent Composable.

createDocument = { handler: (uri: Uri) -> Unit ->
  createDocumentResultLauncher.launch(MimeTypeConstants.JSON)
},

But, I could not figure our how to use the handler now.

Can you please help thank you color .

[Abhimanyu]

I can't move the whole rememberLauncherForActivityResult into the createDocument as it does not have Composable scope.
Also, the SomeClass is Compose independent, so I can't make createDocument into a Composable lambda.

[Timo Drick]

I do use following code for opening documents in Compose:

@Composable
fun rememberFilePicker(): FilePickerState {
    val state = remember { MutableFilePickerState() }
    val launcher = rememberLauncherForActivityResult(
        contract = ActivityResultContracts.OpenDocument(),
        onResult = { uri: Uri? ->
            state.selectedUri = uri
        }
    )
    state.launcher = launcher
    return state
}

interface FilePickerState {
    val selectedUri: Uri?
    fun launchFilePickerIntent(filter: Array<String>)
}

private class MutableFilePickerState() : FilePickerState {
    var launcher: ManagedActivityResultLauncher<Array<String>, Uri?>? = null
    override var selectedUri: Uri? by mutableStateOf(null)
    override fun launchFilePickerIntent(filter: Array<String>) {
        checkNotNull(launcher).launch(filter)
    }
}

Usage in compose is than as follows:

val filePicker = rememberFilePicker()
val selectedAudioUri = filePicker.selectedUri
if (selectedAudioUri != null) {
    AudioPane(
        modifier = Modifier.fillMaxSize(),
        audioUri = selectedAudioUri
    )
} else {
    Button(onClick = { filePicker.launchFilePickerIntent(arrayOf("audio/*")) }) {
        Text("Select music file")
    }
}

Not exactly what you ask for. But i am sure you can change the code that it will fit you needs.
So you could add a lambda parameter to the remember function that is called when the uri is selected.