Introduce onPictureInPictureModeChanged to FlutterPlayerView (PiP #2)

android/src/main/kotlin/com/bitmovin/player/flutter/FlutterPlayerView.kt

@@ -3,6 +3,7 @@ package com.bitmovin.player.flutter
 import android.app.Activity
 import android.content.Context
 import android.content.ContextWrapper
+import android.content.res.Configuration
 import android.view.View
 import androidx.lifecycle.DefaultLifecycleObserver
 import androidx.lifecycle.LifecycleOwner
@@ -37,7 +38,7 @@ class FlutterPlayerView(
             messenger,
         )
 
-    private val playerView: PlayerView = PlayerView(context, player = null)
+    private val playerView = PlayerView(context, player = null)
 
     private val activity =
         context.getActivity()
@@ -79,6 +80,13 @@ class FlutterPlayerView(
         activityLifecycle.addObserver(activityLifecycleObserver)
     }
 
+    private fun onPictureInPictureModeChanged(
+        isInPictureInPictureMode: Boolean,
+        newConfig: Configuration,
+    ) {
+        // TODO: Handle picture in picture mode changed
+    }
+
     override fun onMethodCall(
         call: MethodCall,
         result: MethodChannel.Result,
@@ -111,6 +119,30 @@ class FlutterPlayerView(
         sink = null
     }
 
+    private fun PlayerView.setOnPictureInPictureModeChangedCallback(callback: (Boolean, Configuration) -> Unit) {
+        var isInPictureInPictureMode = activity.isInPictureInPictureMode
+        // Listening to PiP changes usually happens by overriding `onPictureInPictureModeChanged` in the activity.
+        // This is not doable in an SDK context since the library consumer controls the activity.
+        // It's also possible to set a `addOnPictureInPictureModeChangedListener` to the activity that
+        // implements `OnPictureInPictureModeChangedProvider`, unfortunately `FlutterActvity` doesn't implement it.
+        // To work around this limitation we listen to configuration changes and check if the PiP mode changed.
+        // Since Flutter's `PlatformView` isn't actually an Android `View`,
+        // we unfortunately cannot just override the `onConfigurationChanged` function.
+        // Instead, we add a blank `View` to the `PlayerView` and override its `onConfigurationChanged` function.
+        // The alternative would be registering a `ComponentCallbacks` object to the activity,
+        // which doesn't work for some Android versions (tested on Android 10 with FlutterFragmentActivity).
+        addView(
+            object : View(context) {
+                override fun onConfigurationChanged(newConfig: Configuration) {
+                    if (isInPictureInPictureMode != activity.isInPictureInPictureMode) {
+                        isInPictureInPictureMode = activity.isInPictureInPictureMode
+                        callback(isInPictureInPictureMode, newConfig)
+                    }
+                }
+            },
+        )
+    }
+
     private fun Context.getActivity(): Activity? =
         when (this) {
             is Activity -> this