Flow that Immediately emits a set of AudioDeviceInfo's, i.e the current audio devices that are connected, followed by updates as devices are connect and disconnected. Useful for monitoring currently connected headphones

Headphone Monitor.kt

package com.klefmusic.eightbars.utils

import android.content.Context
import android.media.AudioDeviceCallback
import android.media.AudioDeviceInfo
import android.media.AudioManager
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.channels.Channel
import kotlinx.coroutines.channels.awaitClose
import kotlinx.coroutines.channels.sendBlocking
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.buffer
import kotlinx.coroutines.flow.callbackFlow


/**
 * Immediately emits a set of [AudioDeviceInfo], i.e the current audio devices that are connected,
 * followed by updates as devices are connect and disconnected.
 *
 * @param context android context.
 * @param flags A set of bitflags specifying the criteria to test.
 * @see [AudioManager.GET_DEVICES_OUTPUTS]
 * @see [AudioManager.GET_DEVICES_INPUTS]
 * @see [AudioManager.GET_DEVICES_INPUTS]
 */
@ExperimentalCoroutinesApi
fun audioDevices(context: Context, flags: Int): Flow<Set<AudioDeviceInfo>> = callbackFlow<Set<AudioDeviceInfo>>{
    val myAudioManager : AudioManager = context.getSystemService (Context.AUDIO_SERVICE)  as AudioManager
    val audioDevices: MutableSet<AudioDeviceInfo> = mutableSetOf(*myAudioManager.getDevices(
        AudioManager.GET_DEVICES_OUTPUTS
    ))

    val callback = object : AudioDeviceCallback() {

        override fun onAudioDevicesAdded(addedDevices: Array<AudioDeviceInfo>) {
            super.onAudioDevicesAdded(addedDevices)
            audioDevices.addAll(addedDevices)
            sendBlocking(audioDevices)
        }

        override fun onAudioDevicesRemoved(removedDevices: Array<AudioDeviceInfo>) {
            super.onAudioDevicesRemoved(removedDevices)
            audioDevices.removeAll(removedDevices)
            sendBlocking(audioDevices)
        }
    }
    myAudioManager.registerAudioDeviceCallback(callback, null)

    awaitClose {
        myAudioManager.unregisterAudioDeviceCallback(callback)
    }
}.buffer(capacity = Channel.CONFLATED)



/**
 * Immediately emits a set of [AudioDeviceInfo], i.e the current audio devices that are connected,
 * followed by updates as devices are connect and disconnected.
 *
 * @param context android context.
 * @param flags A set of bitflags specifying the criteria to test.
 * @see [AudioManager.GET_DEVICES_OUTPUTS]
 * @see [AudioManager.GET_DEVICES_INPUTS]
 * @see [AudioManager.GET_DEVICES_INPUTS]
 */
@ExperimentalCoroutinesApi
@JvmName("audioDevicesExt")
fun Context.audioDevices(flags: Int) : Flow<Set<AudioDeviceInfo>> = audioDevices(this, flags)