Issue googlecast#124 Fix Cast button visibility

Add empty callback to MediaRouter to avoid losing cast button when
activity is paused

app-java/src/main/java/com/google/sample/cast/refplayer/VideoBrowserActivity.java

@@ -16,6 +16,22 @@
 
 package com.google.sample.cast.refplayer;
 
+import android.content.Intent;
+import android.net.Uri;
+import android.os.Bundle;
+import android.os.Handler;
+import android.util.Log;
+import android.view.KeyEvent;
+import android.view.Menu;
+import android.view.MenuItem;
+
+import androidx.annotation.NonNull;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.Toolbar;
+import androidx.mediarouter.media.MediaControlIntent;
+import androidx.mediarouter.media.MediaRouteSelector;
+import androidx.mediarouter.media.MediaRouter;
+
 import com.google.android.gms.cast.framework.CastButtonFactory;
 import com.google.android.gms.cast.framework.CastContext;
 import com.google.android.gms.cast.framework.CastSession;
@@ -26,19 +42,6 @@
 import com.google.sample.cast.refplayer.queue.ui.QueueListViewActivity;
 import com.google.sample.cast.refplayer.settings.CastPreference;
 
-import android.content.Intent;
-import android.net.Uri;
-import android.os.Bundle;
-import android.os.Handler;
-import androidx.annotation.NonNull;
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.appcompat.widget.Toolbar;
-
-import android.util.Log;
-import android.view.KeyEvent;
-import android.view.Menu;
-import android.view.MenuItem;
-
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 
@@ -58,6 +61,9 @@ public class VideoBrowserActivity extends AppCompatActivity {
     private IntroductoryOverlay mIntroductoryOverlay;
     private CastStateListener mCastStateListener;
     private Executor localExecutor = Executors.newSingleThreadExecutor();
+    private MediaRouter mRouter;
+    private MediaRouter.Callback mCallback = new MyCallback();
+    private MediaRouteSelector mSelector;
 
     private class MySessionManagerListener implements SessionManagerListener<CastSession> {
 
@@ -126,6 +132,12 @@ public void onCastStateChanged(int newState) {
             }
         };
         mCastContext = CastContext.getSharedInstance(this,localExecutor).getResult();
+
+        mRouter = MediaRouter.getInstance(this);
+        mSelector = new MediaRouteSelector.Builder()
+                .addControlCategory(MediaControlIntent.CATEGORY_LIVE_AUDIO)
+                .addControlCategory(MediaControlIntent.CATEGORY_REMOTE_PLAYBACK)
+                .build();
     }
 
     private void setupActionBar() {
@@ -200,6 +212,20 @@ protected void onResume() {
         super.onResume();
     }
 
+    @Override
+    public void onStart() {
+        super.onStart();
+
+        mRouter.addCallback(mSelector, mCallback, MediaRouter.CALLBACK_FLAG_REQUEST_DISCOVERY);
+    }
+
+    @Override
+    public void onStop() {
+        mRouter.addCallback(mSelector, mCallback, /* flags= */ 0);
+
+        super.onStop();
+    }
+
     @Override
     protected void onPause() {
         mCastContext.removeCastStateListener(mCastStateListener);
@@ -208,6 +234,14 @@ protected void onPause() {
         super.onPause();
     }
 
+    @Override
+    public void onDestroy() {
+        // Remove the callback when the activity is destroyed.
+        mRouter.removeCallback(mCallback);
+
+        super.onDestroy();
+    }
+
     private void showIntroductoryOverlay() {
         if (mIntroductoryOverlay != null) {
             mIntroductoryOverlay.remove();
@@ -234,4 +268,7 @@ public void onOverlayDismissed() {
             });
         }
     }
+
+    private final class MyCallback extends MediaRouter.Callback {
+    }
 }

app-kotlin/src/main/kotlin/com/google/sample/cast/refplayer/VideoBrowserActivity.kt

@@ -15,29 +15,31 @@
  */
 package com.google.sample.cast.refplayer
 
-import androidx.appcompat.app.AppCompatActivity
-import com.google.android.gms.cast.framework.CastContext
-import com.google.android.gms.cast.framework.SessionManagerListener
-import com.google.android.gms.cast.framework.CastSession
-import android.view.MenuItem
-import com.google.android.gms.cast.framework.IntroductoryOverlay
-import com.google.android.gms.cast.framework.CastStateListener
-import android.os.Bundle
-import com.google.android.gms.cast.framework.CastState
-import android.view.View
 import android.content.Intent
 import android.net.Uri
+import android.os.Bundle
 import android.os.Handler
 import android.os.Looper
 import android.util.Log
-import android.view.Menu
-import com.google.android.gms.cast.framework.CastButtonFactory
 import android.view.KeyEvent
+import android.view.Menu
+import android.view.MenuItem
+import android.view.View
+import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.Toolbar
+import androidx.mediarouter.media.MediaControlIntent
+import androidx.mediarouter.media.MediaRouteSelector
+import androidx.mediarouter.media.MediaRouter
+import com.google.android.gms.cast.framework.CastButtonFactory
+import com.google.android.gms.cast.framework.CastContext
+import com.google.android.gms.cast.framework.CastSession
+import com.google.android.gms.cast.framework.CastState
+import com.google.android.gms.cast.framework.CastStateListener
+import com.google.android.gms.cast.framework.IntroductoryOverlay
+import com.google.android.gms.cast.framework.SessionManagerListener
 import com.google.sample.cast.refplayer.queue.ui.QueueListViewActivity
 import com.google.sample.cast.refplayer.settings.CastPreference
 import java.util.concurrent.Executor
-import java.util.concurrent.ExecutorService
 import java.util.concurrent.Executors
 
 /**
@@ -53,6 +55,12 @@ class VideoBrowserActivity : AppCompatActivity() {
     private var mIntroductoryOverlay: IntroductoryOverlay? = null
     private var mCastStateListener: CastStateListener? = null
     private val  castExecutor: Executor = Executors.newSingleThreadExecutor();
+    private var mediaRouter: MediaRouter? = null
+    private var mediaRouterCallback = object : MediaRouter.Callback() {}
+    private var mediaRouteSelector: MediaRouteSelector = MediaRouteSelector.Builder()
+        .addControlCategory(MediaControlIntent.CATEGORY_LIVE_AUDIO)
+        .addControlCategory(MediaControlIntent.CATEGORY_REMOTE_PLAYBACK)
+        .build()
 
     private inner class MySessionManagerListener : SessionManagerListener<CastSession> {
         override fun onSessionEnded(session: CastSession, error: Int) {
@@ -90,6 +98,7 @@ class VideoBrowserActivity : AppCompatActivity() {
             }
         }
         mCastContext = CastContext.getSharedInstance(this,castExecutor).result
+        mediaRouter = MediaRouter.getInstance(this)
     }
 
     private fun setupActionBar() {
@@ -158,6 +167,15 @@ class VideoBrowserActivity : AppCompatActivity() {
         super.onResume()
     }
 
+    override fun onStart() {
+        mediaRouter?.addCallback(
+            mediaRouteSelector,
+            mediaRouterCallback,
+            MediaRouter.CALLBACK_FLAG_REQUEST_DISCOVERY
+        )
+        super.onStart()
+    }
+
     override fun onPause() {
         mCastContext!!.removeCastStateListener(mCastStateListener!!)
         mCastContext!!.sessionManager.removeSessionManagerListener(
@@ -166,6 +184,16 @@ class VideoBrowserActivity : AppCompatActivity() {
         super.onPause()
     }
 
+    override fun onStop() {
+        mediaRouter?.addCallback(mediaRouteSelector, mediaRouterCallback, 0)
+        super.onStop()
+    }
+
+    override fun onDestroy() {
+        mediaRouter?.removeCallback(mediaRouterCallback)
+        super.onDestroy()
+    }
+
     private fun showIntroductoryOverlay() {
         if (mIntroductoryOverlay != null) {
             mIntroductoryOverlay!!.remove()
@@ -188,4 +216,4 @@ class VideoBrowserActivity : AppCompatActivity() {
     companion object {
         private const val TAG = "VideoBrowserActivity"
     }
-}
+}