how to show my screen alarm from background manager

Question

I installed android alarm manager package and print code on background its work well. But how can show my alarm screen like WhatsApp receive call for example, can I do this with flutter ?

void runOnBackGround() async {
  final int helloAlarmID = 0;
  await AndroidAlarmManager.initialize();
  await AndroidAlarmManager.periodic(
      const Duration(seconds: 1), helloAlarmID, callBack,
      wakeup: true);
}

void callBack(i) async {
  final DateTime now = DateTime.now();
  print("[$now] id = $i Hello, world! ");
}

Answer 1

Well in my case, I modified the plugin code and needed some permission. I found this solution from geisterfurz007/random-alarm. It makes can show the app from the background.

1. Modifying plugin

EDIT: To open an app when an alarm goes off, Need to modify the plugin.

Open the project and find the android_alarm_manager-2.0.0 in the External Libraries/Flutter Plugins. And find AlarmBroadcastReceiver.java, copy-paste the following code. That code is from the flutter issue.

AlarmBroadcastReceiver.java

// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
     
package io.flutter.plugins.androidalarmmanager;
     
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.PowerManager;
import android.content.pm.PackageManager;
import android.view.WindowManager;
     
public class AlarmBroadcastReceiver extends BroadcastReceiver {
  private static PowerManager.WakeLock wakeLock;
     
  @Override
  public void onReceive(Context context, Intent intent) {
    PowerManager powerManager = (PowerManager)
            context.getSystemService(Context.POWER_SERVICE);
    wakeLock = powerManager.newWakeLock(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON |
            PowerManager.ACQUIRE_CAUSES_WAKEUP |
            PowerManager.ON_AFTER_RELEASE, "My wakelock");
     
    Intent startIntent = context
            .getPackageManager()
            .getLaunchIntentForPackage(context.getPackageName());
     
    startIntent.setFlags(
            Intent.FLAG_ACTIVITY_REORDER_TO_FRONT |
                    Intent.FLAG_ACTIVITY_NEW_TASK |
                    Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED
    );
     
    wakeLock.acquire();
    context.startActivity(startIntent);
    AlarmService.enqueueAlarmProcessing(context, intent);
    wakeLock.release();
  }
}

2. Permissions

There is a need for permission to run the app when the alarm goes off from the background.

• Display over other apps
• Ignore battery optimization

You can access permissions by using permission_handler.