fix: Fixed the background playback of video issue. (#81)

* fix: Fixed the background playback of video issue.

* fix: Edge case fix when the video was originally paused and then we go out and come back into the view

Author: pratikbaid3

lib/screens/vlc_stream.dart

@@ -14,7 +14,7 @@ class VlcStream extends StatefulWidget {
   _VlcStreamState createState() => _VlcStreamState();
 }
 
-class _VlcStreamState extends State<VlcStream> {
+class _VlcStreamState extends State<VlcStream> with WidgetsBindingObserver {
   // state of media player while playing
   bool isPlaying = true;
 
@@ -27,6 +27,8 @@ class _VlcStreamState extends State<VlcStream> {
   // hide control buttons {play/pause and seek slider} while playing media
   bool showControls = true;
 
+  bool isPausedDueToLifecycle = false;
+
   _initVlcPlayer() async {
     _videoViewController = new VlcPlayerController(onInit: () {
       _videoViewController.play();
@@ -62,6 +64,7 @@ class _VlcStreamState extends State<VlcStream> {
     if (state == PlayingState.PLAYING) {
       _videoViewController.pause();
       setState(() {
+        isPausedDueToLifecycle = false;
         isPlaying = false;
       });
     } else {
@@ -72,9 +75,38 @@ class _VlcStreamState extends State<VlcStream> {
     }
   }
 
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    if (state == AppLifecycleState.detached ||
+        state == AppLifecycleState.inactive ||
+        state == AppLifecycleState.paused) {
+      //The app is either in bg or the phone has been turned off
+      PlayingState state = _videoViewController.playingState;
+      if (state == PlayingState.PLAYING) {
+        //Check if the video is playing and only then execute pause operation
+        _videoViewController.pause();
+        setState(() {
+          //Keeping track if the video is paused due to lifecycle change
+          isPausedDueToLifecycle = true;
+          isPlaying = false;
+        });
+      }
+    }
+    //Only is the video was paused due to lifecycle changes
+    if (state == AppLifecycleState.resumed && isPausedDueToLifecycle) {
+      //The app is bought back into the view or the display is turned back on
+      _videoViewController.play();
+      setState(() {
+        isPlaying = true;
+      });
+    }
+    super.didChangeAppLifecycleState(state);
+  }
+
   @override
   void initState() {
     super.initState();
+    WidgetsBinding.instance.addObserver(this);
     _initVlcPlayer();
     SystemChrome.setEnabledSystemUIOverlays([]);
     Wakelock.enable();
@@ -196,6 +228,7 @@ class _VlcStreamState extends State<VlcStream> {
 
   @override
   void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
     Wakelock.disable();
     SystemChrome.setEnabledSystemUIOverlays(SystemUiOverlay.values);
     super.dispose();