Handle Activity going into Background on Android

android/app/src/main/AndroidManifest.xml

@@ -23,6 +23,7 @@
         <activity
             android:name=".stream.StreamActivity"
             android:theme="@style/StreamTheme"
+            android:configChanges="keyboard|keyboardHidden|orientation|screenSize"
             android:screenOrientation="userLandscape"/>
     </application>
 

android/app/src/main/java/com/metallic/chiaki/StreamSession.kt

@@ -45,13 +45,31 @@ class StreamSession(val connectInfo: ConnectInfo)
 
 	var surfaceTexture: SurfaceTexture? = null
 
-	init
+	fun shutdown()
 	{
+		session?.stop()
+		session?.dispose()
+		session = null
+		//surfaceTexture?.release()
+	}
+
+	fun pause()
+	{
+		shutdown()
+	}
+
+	fun resume()
+	{
+		if(session != null)
+			return
 		try
 		{
 			val session = Session(connectInfo)
 			session.eventCallback = this::eventCallback
 			session.start()
+			val surfaceTexture = surfaceTexture
+			if(surfaceTexture != null)
+				session.setSurface(Surface(surfaceTexture))
 			this.session = session
 		}
 		catch(e: SessionCreateError)
@@ -60,13 +78,6 @@ class StreamSession(val connectInfo: ConnectInfo)
 		}
 	}
 
-	fun shutdown()
-	{
-		session?.stop()
-		session?.dispose()
-		surfaceTexture?.release()
-	}
-
 	private fun eventCallback(event: Event)
 	{
 		when(event)

android/app/src/main/java/com/metallic/chiaki/stream/StreamActivity.kt

@@ -23,8 +23,7 @@ import android.util.Log
 import android.view.KeyEvent
 import android.view.View
 import androidx.appcompat.app.AppCompatActivity
-import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProviders
+import androidx.lifecycle.*
 import com.metallic.chiaki.R
 import com.metallic.chiaki.lib.ConnectInfo
 import kotlinx.android.synthetic.main.activity_stream.*
@@ -70,6 +69,13 @@ class StreamActivity : AppCompatActivity()
 	{
 		super.onResume()
 		hideSystemUI()
+		viewModel.session.resume()
+	}
+
+	override fun onPause()
+	{
+		super.onPause()
+		viewModel.session.pause()
 	}
 
 	override fun onWindowFocusChanged(hasFocus: Boolean)

android/app/src/main/java/com/metallic/chiaki/stream/StreamViewModel.kt

@@ -23,17 +23,15 @@ import com.metallic.chiaki.lib.*
 
 class StreamViewModel: ViewModel()
 {
-	var isInitialized = false
-		private set(value) { field = value}
-
+	private var connectInfo: ConnectInfo? = null
 	private var _session: StreamSession? = null
 	val session: StreamSession get() = _session ?: throw UninitializedPropertyAccessException("StreamViewModel not initialized")
+	val isInitialized get() = connectInfo != null
 
 	fun init(connectInfo: ConnectInfo)
 	{
 		if(isInitialized)
 			return
-		isInitialized = true
 		_session = StreamSession(connectInfo)
 	}