Android: Persistent notification while ingame (#13125)

Co-authored-by: Lars Müller <34514239+appgurueu@users.noreply.github.com>
Co-authored-by: grorp <grorp@posteo.de>

android/app/src/main/java/net/minetest/minetest/GameActivity.java

@@ -22,14 +22,19 @@ package net.minetest.minetest;
 
 import org.libsdl.app.SDLActivity;
 
+import android.app.Notification;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.Context;
 import android.content.Intent;
 import android.content.ActivityNotFoundException;
 import android.net.Uri;
-import android.os.Bundle;
+import android.os.Build;
+import android.os.Handler;
+import android.os.Looper;
 import android.text.InputType;
 import android.util.Log;
 import android.view.KeyEvent;
-import android.view.View;
 import android.view.WindowManager;
 import android.view.inputmethod.InputMethodManager;
 import android.widget.Button;
@@ -91,6 +96,9 @@ public class GameActivity extends SDLActivity {
 		saveSettings();
 	}
 
+	private NotificationManager mNotifyManager;
+	private boolean gameNotificationShown = false;
+
 	public void showTextInputDialog(String hint, String current, int editType) {
 		runOnUiThread(() -> showTextInputDialogUI(hint, current, editType));
 	}
@@ -263,4 +271,67 @@ public class GameActivity extends SDLActivity {
 	public boolean hasPhysicalKeyboard() {
 		return getContext().getResources().getConfiguration().keyboard != Configuration.KEYBOARD_NOKEYS;
 	}
+
+	// TODO: share code with UnzipService.createNotification
+	private void updateGameNotification() {
+		if (mNotifyManager == null) {
+			mNotifyManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
+		}
+
+		if (!gameNotificationShown) {
+			mNotifyManager.cancel(MainActivity.NOTIFICATION_ID_GAME);
+			return;
+		}
+
+		Notification.Builder builder;
+		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+			builder = new Notification.Builder(this, MainActivity.NOTIFICATION_CHANNEL_ID);
+		} else {
+			builder = new Notification.Builder(this);
+		}
+
+		Intent notificationIntent = new Intent(this, GameActivity.class);
+		notificationIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP
+			| Intent.FLAG_ACTIVITY_SINGLE_TOP);
+		int pendingIntentFlag = 0;
+		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+			pendingIntentFlag = PendingIntent.FLAG_MUTABLE;
+		}
+		PendingIntent intent = PendingIntent.getActivity(this, 0,
+			notificationIntent, pendingIntentFlag);
+
+		builder.setContentTitle(getString(R.string.game_notification_title))
+			.setSmallIcon(R.mipmap.ic_launcher)
+			.setContentIntent(intent)
+			.setOngoing(true);
+
+		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+			// This avoids a stuck notification if the app is killed while
+			// in-game: (1) if the user closes the app from the "Recents" screen
+			// or (2) if the system kills the app while it is in background.
+			// onStop is called too early to remove the notification and
+			// onDestroy is often not called at all, so there's this hack instead.
+			builder.setTimeoutAfter(16000);
+
+			// Replace the notification just before it expires as long as the app is
+			// running (and we're still in-game).
+			final Handler handler = new Handler(Looper.getMainLooper());
+			handler.postDelayed(new Runnable() {
+				@Override
+				public void run() {
+					if (gameNotificationShown) {
+						updateGameNotification();
+					}
+				}
+			}, 15000);
+		}
+
+		mNotifyManager.notify(MainActivity.NOTIFICATION_ID_GAME, builder.build());
+	}
+
+
+	public void setPlayingNowNotification(boolean show) {
+		gameNotificationShown = show;
+		updateGameNotification();
+	}
 }

android/app/src/main/java/net/minetest/minetest/MainActivity.java

@@ -43,6 +43,8 @@ import static net.minetest.minetest.UnzipService.*;
 
 public class MainActivity extends AppCompatActivity {
 	public static final String NOTIFICATION_CHANNEL_ID = "Minetest channel";
+	public static final int NOTIFICATION_ID_UNZIP = 1;
+	public static final int NOTIFICATION_ID_GAME = 2;
 
 	private final static int versionCode = BuildConfig.VERSION_CODE;
 	private static final String SETTINGS = "MinetestSettings";

android/app/src/main/java/net/minetest/minetest/UnzipService.java

@@ -51,7 +51,6 @@ public class UnzipService extends IntentService {
 	public static final int SUCCESS = -1;
 	public static final int FAILURE = -2;
 	public static final int INDETERMINATE = -3;
-	private final int id = 1;
 	private NotificationManager mNotifyManager;
 	private boolean isSuccess = true;
 	private String failureMessage;
@@ -100,11 +99,14 @@ public class UnzipService extends IntentService {
 		}
 	}
 
+	// TODO: share code with GameActivity.updateGameNotification
 	@NonNull
 	private Notification.Builder createNotification() {
-		Notification.Builder builder;
+		if (mNotifyManager == null) {
-		if (mNotifyManager == null)
 			mNotifyManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
+		}
+
+		Notification.Builder builder;
 		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
 			builder = new Notification.Builder(this, MainActivity.NOTIFICATION_CHANNEL_ID);
 		} else {
@@ -128,7 +130,7 @@ public class UnzipService extends IntentService {
 				.setOngoing(true)
 				.setProgress(0, 0, true);
 
-		mNotifyManager.notify(id, builder.build());
+		mNotifyManager.notify(MainActivity.NOTIFICATION_ID_UNZIP, builder.build());
 		return builder;
 	}
 
@@ -200,14 +202,14 @@ public class UnzipService extends IntentService {
 			} else {
 				notificationBuilder.setProgress(100, progress, false);
 			}
-			mNotifyManager.notify(id, notificationBuilder.build());
+			mNotifyManager.notify(MainActivity.NOTIFICATION_ID_UNZIP, notificationBuilder.build());
 		}
 	}
 
 	@Override
 	public void onDestroy() {
 		super.onDestroy();
-		mNotifyManager.cancel(id);
+		mNotifyManager.cancel(MainActivity.NOTIFICATION_ID_UNZIP);
 		publishProgress(null, R.string.loading, isSuccess ? SUCCESS : FAILURE);
 	}
 }

android/app/src/main/res/values/strings.xml

@@ -6,6 +6,7 @@
 	<string name="notification_channel_description">Notifications from Luanti</string>
 	<string name="unzip_notification_title">Loading Luanti</string>
 	<string name="unzip_notification_description">Less than 1 minute&#8230;</string>
+	<string name="game_notification_title">Luanti is running</string>
 	<string name="ime_dialog_done">Done</string>
 	<string name="no_web_browser">No web browser found</string>
 </resources>

src/client/game.cpp

@@ -1021,6 +1021,10 @@ void Game::run()
 	const bool initial_window_maximized = !g_settings->getBool("fullscreen") &&
 			g_settings->getBool("window_maximized");
 
+#ifdef __ANDROID__
+	porting::setPlayingNowNotification(true);
+#endif
+
 	auto framemarker = FrameMarker("Game::run()-frame").started();
 
 	while (m_rendering_engine->run()
@@ -1103,6 +1107,10 @@ void Game::run()
 
 	framemarker.end();
 
+#ifdef __ANDROID__
+	porting::setPlayingNowNotification(false);
+#endif
+
 	RenderingEngine::autosaveScreensizeAndCo(initial_screen_size, initial_window_maximized);
 }
 

src/porting_android.cpp

@@ -187,6 +187,18 @@ void shareFileAndroid(const std::string &path)
 	jnienv->CallVoidMethod(activity, url_open, jurl);
 }
 
+void setPlayingNowNotification(bool show)
+{
+	jmethodID play_notification = jnienv->GetMethodID(activityClass,
+			"setPlayingNowNotification", "(Z)V");
+
+	FATAL_ERROR_IF(play_notification == nullptr,
+			"porting::setPlayingNowNotification unable to find Java setPlayingNowNotification method");
+
+	jboolean jshow = show;
+	jnienv->CallVoidMethod(activity, play_notification, jshow);
+}
+
 AndroidDialogType getLastInputDialogType()
 {
 	jmethodID lastdialogtype = jnienv->GetMethodID(activityClass,

src/porting_android.h

@@ -36,6 +36,13 @@ void showComboBoxDialog(const std::string *optionList, s32 listSize, s32 selecte
  */
 void shareFileAndroid(const std::string &path);
 
+/**
+ * Shows/hides notification that the game is running
+ *
+ * @param show whether to show/hide the notification
+ */
+void setPlayingNowNotification(bool show);
+
 /*
  * Types of Android input dialog:
  * 1. Text input (single/multi-line text and password field)