I am currently developing an android xamarin app (android 6 and above) and I have got a problem.
Our customer wants to secure the app by a pinpad. Whenever the app is started the user has to enter a four digit pin.
We have created an activity for the pinpad. This works pretty fine, but the problem is the following:
The pinpad just opens if the app was completely killed (e.g. by the task manager ) -> cold started.
How can I achive that the pinpad opens if the app was in the background and reopend by the task manager for example (user pressed home button and then wants to start app again) -> warm started.
I've tried to do this by OnResume(), OnStart(),. But unfortunately they trigger every time an another activity (e.g. open detail view of list item) is opened.
use IActivityLifecycleCallbacks to listen the status.
Application registration ActivityLifecycleCallbacks, such, when each activity in the app lifecycle occurs, the Application can be listening to. The number of public void onActivityStarted(activity activity) and public void onActivityStopped(activity activity) of an activity can be used to determine whether the app is in the foreground. Because when the app is in the foreground, an activity must have started onActivityStarted but not onActivityStopped, so the statistics of the number of activities opened in the app must be 1. When the app switches to the background, activityStartCount will be 0.
so write a Helper classes :
public class AppFrontBackHelper
{
public static OnAppStatusListener mOnAppStatusListener;
private LifecycleCallBack lifecycleCallBack;
public AppFrontBackHelper()
{
}
/**
* Register status listener, only used in Application
* #param application
* #param listener
*/
public void register(Application application, OnAppStatusListener listener)
{
mOnAppStatusListener = listener;
lifecycleCallBack = new LifecycleCallBack();
application.RegisterActivityLifecycleCallbacks(lifecycleCallBack);
}
public void unRegister(Application application) => application.UnregisterActivityLifecycleCallbacks(lifecycleCallBack);
public interface OnAppStatusListener
{
void onFront();
void onBack();
}
public class LifecycleCallBack : Java.Lang.Object, Application.IActivityLifecycleCallbacks
{
public int activityStartCount { get; private set; }
public void OnActivityCreated(Activity activity, Bundle savedInstanceState)
{
}
public void OnActivityDestroyed(Activity activity)
{
}
public void OnActivityPaused(Activity activity)
{
}
public void OnActivityResumed(Activity activity)
{
}
public void OnActivitySaveInstanceState(Activity activity, Bundle outState)
{
}
public void OnActivityStarted(Activity activity)
{
activityStartCount++;
//A value from 1 to 0 indicates cutting from the background to the foreground
if (activityStartCount == 1)
{
if (mOnAppStatusListener != null)
{
mOnAppStatusListener.onFront();
}
}
}
public void OnActivityStopped(Activity activity)
{
activityStartCount--;
//A value from 1 to 0 indicates cutting from the foreground to the background
if (activityStartCount == 0)
{
//从前台切到后台
if (mOnAppStatusListener != null)
{
mOnAppStatusListener.onBack();
}
}
}
}
}
then custom an Application and regist the listener :
[Application]
public class MyApplication : Application,AppFrontBackHelper.OnAppStatusListener
{
protected MyApplication(IntPtr javaReference, JniHandleOwnership transfer) : base(javaReference, transfer)
{
}
public override void OnCreate()
{
base.OnCreate();
AppFrontBackHelper appFrontBackHelper = new AppFrontBackHelper();
appFrontBackHelper.register(this, this);
}
public void onBack()
{
Toast.MakeText(this, "from front to back", ToastLength.Short).Show();
}
public void onFront()
{
Toast.MakeText(this, "from back to front", ToastLength.Short).Show();
}
}
you could do something in the onFront() callback.
Related
I have a service that listens to media buttons, but I only want to listen to those when my service is running since I have a button on the UI to start/stop the service.
How can I achieve the following two actions:
On MyService start-up, start receiving media button events to com.myApp/MyService.
On MyService end, stop receiving media button events in com.myApp/MyService.
The related logs are the following:
D MediaSessionService: Sending KeyEvent { action=ACTION_DOWN, keyCode=KEYCODE_HEADSETHOOK, scanCode=226, metaState=0, flags=0x8, repeatCount=0, eventTime=13258317, downTime=13258317, deviceId=4, source=0x101 } to com.myApp/MyService (userId=0)
Note:
I found out that I can start receiving media events after my app started to play audio. This is however not ideal, since I don't want to play audio in my app. (I am only using media events in order to trigger voice recognition)
After I played audio, my service is apparently the default media receiver. This means that when a media button is pressed, my service get instantiated, does nothing, and get destroyed. This is not an idea behavior for the end user since my app ends up 'stealing' these events that could potentially be handled by something else.
Overriding OnStartCommand() in my service does not help
Calling SetMediaButtonReceiver on the MediaSession does not help either
Using a BroadcastReceiver with the intent "android.intent.action.MEDIA_BUTTON" registered in the AudioManager does not work either
Relevant code (in C#, I am on Xamarin.Forms, but that should not have any impact on the way to achieve this)
public class MediaSessionCompatCallback : MediaSessionCompat.Callback
{
public Func<Intent, bool> MediaButtonEvent { get; set; }
public override bool OnMediaButtonEvent(Intent mediaButtonEvent) => MediaButtonEvent?.Invoke(mediaButtonEvent) ?? false;
}
[Service(Exported = true, Enabled = true)]
[IntentFilter(new[] { ServiceInterface })]
public class MediaBrowserService : MediaBrowserServiceCompat, AudioManager.IOnAudioFocusChangeListener
{
private MediaSessionCompat mediaSession;
private MediaSessionCompatCallback mediaSessionCallback;
private void CreateMediaSessionCallback()
{
mediaSessionCallback = new MediaSessionCompatCallback()
{
MediaButtonEvent = OnMediaButtonEvent
};
}
private void SetupMediaSession()
{
CreateMediaSessionCallback();
var stateBuilder = new PlaybackStateCompat.Builder().SetActions(PlaybackStateCompat.ActionPlay | PlaybackStateCompat.ActionPlayPause);
mediaSession = new MediaSessionCompat(this, nameof(MediaBrowserService));
mediaSession.SetFlags(MediaSessionCompat.FlagHandlesMediaButtons | MediaSessionCompat.FlagHandlesTransportControls);
mediaSession.SetPlaybackState(stateBuilder.Build());
mediaSession.SetCallback(mediaSessionCallback);
mediaSession.Active = true;
SessionToken = mediaSession.SessionToken;
}
private void BuildNotification() { [...] }
public override void OnCreate()
{
base.OnCreate();
SetupMediaSession();
StartForeground(135, BuildNotification());
ContextCompat.StartForegroundService(ApplicationContext, new Intent(ApplicationContext, Java.Lang.Class.FromType(typeof(MediaBrowserService))));
}
public override void OnDestroy()
{
base.OnDestroy();
if (mediaSession != null)
{
mediaSession.Active = false;
mediaSession.SetCallback(null);
mediaSession.Release();
mediaSession.Dispose();
mediaSession = null;
}
if (mediaSessionCallback != null)
{
mediaSessionCallback.Dispose();
mediaSessionCallback = null;
}
StopForeground(true);
StopSelf();
}
}
I am using Xamarin Android to build an app which should allow the app to keep sending a driver's location every 15 minutes so that I can keep track of his movement. I used JobScheduler to get this done. My project is very simple now and only contains the following 3 files:
MainActivity.cs
AttendancePage.cs (Content page, interact with UI button to start the service)
ServiceClass.cs
Methods in Main Activity.cs
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
scheduler = (JobScheduler)GetSystemService(JobSchedulerService);
LoadApplication(new App()); //This line will then jump to AttendancePage.cs
}
public void ScheduleJob()
{
ComponentName componentName = new ComponentName(this, Java.Lang.Class.FromType(typeof(ServiceClass)));
JobInfo info = new JobInfo.Builder(123, componentName)
.SetPersisted(true)
.SetPeriodic(60000)
.Build();
int resultCode = scheduler.Schedule(info); //The error show when hit this line.
if (resultCode == JobScheduler.ResultSuccess)
{
Log.Info("Message", "Job Schedule!");
}
else
{
Log.Info("Message", "Job shceduling failed");
}
}
public void CancelJob()
{
scheduler.Cancel(123);
}
AttendancePage.cs
public partial class AttendancePage : ContentPage
{
MainActivity main = new MainActivity();
public AttendancePage()
{
InitializeComponent();
Title = "Attendance App";
}
//Button OnClickEvent
async void ScheduleJob(object s, EventArgs e)
{
main.ScheduleJob();
}
//Button OnClickEvent
async void CancelJob(object s, EventArgs e)
{
main.CancelJob();
}
}
ServiceClass.cs
[Service(Name = "com.SampleApp.AttendanceApp.ServiceClass", Permission = "android.permission.BIND_JOB_SERVICE")]
public class ServiceClass : JobService
{
public ServiceClass()
{
}
public override bool OnStartJob(JobParameters jobParamsOnStart)
{
doBackgroundWork(jobParamsOnStart);
return true;
}
private void doBackgroundWork(JobParameters jobParam)
{
//My code to send driver's location
TestingPage.GetGPS();
JobFinished(jobParam, false);
}
public override bool OnStopJob(JobParameters jobParamsOnStop)
{
return false;
}
}
I have added the service tag inside AndroidManifest.xml as well.
<service android:name=".ServiceClass"
android:permission="android.permission.BIND_JOB_SERVICE"
android:exported="true" />
I have no idea why the error is still there. The error is from the line scheduler.Schedule(JobInfo). Anyone has another possible solution? I am frustrated on solving this. Will the reason be I can't debug on the service but only can straight away run in release mode? Please help.
Froms shared code it works in Xamarin.Android project , however here is a Xamarin.Forms project . It can not work.
In AttendancePage.cs , you create a new MainActivity to invoke the native method ScheduleJob and CancelJob . This will not find the JobScheduler in native ,then it will return null .
No such service ComponentInfo{/com.SampleApp.AttendanceApp.ServiceClass}
If you want to invoke native method , you can have a try with DependencyService in Xamarin Forms .
At least need to create a Interface in Forms to invoke :
public interface IJobSchedulerService
{
//Start JobSchedule
void StartJobSchedule();
//Cancel JobSchedule
void CancelJobSchedule();
}
Then can invoke in Xamarin Forms as follow :
async void ScheduleJob(object s, EventArgs e)
{
DependencyService.Get<IJobSchedulerService>().StartJobSchedule();
}
//Button OnClickEvent
async void CancelJob(object s, EventArgs e)
{
DependencyService.Get<IJobSchedulerService>().CancelJobSchedule();
}
Now you need to implement the IJobSchedulerService in native android .Create the JobSchedulerDependcenyService:
public class JobSchedulerDependcenyService : IJobSchedulerService
{
JobScheduler jobScheduler;
public JobSchedulerDependcenyService()
{
jobScheduler = (JobScheduler)MainActivity.Instance.GetSystemService(Android.Content.Context.JobSchedulerService);
}
public void StartJobSchedule()
{
ComponentName componentName = new ComponentName(MainActivity.Instance, Java.Lang.Class.FromType(typeof(DownloadJob)));
JobInfo jobInfo = new JobInfo.Builder(1, componentName)
.SetOverrideDeadline(0)
.Build();
//var jobScheduler = (JobScheduler)GetSystemService(JobSchedulerService);
var scheduleResult = jobScheduler.Schedule(jobInfo);
if (JobScheduler.ResultSuccess == scheduleResult)
{
var snackBar = Snackbar.Make(MainActivity.Instance.FindViewById(Android.Resource.Id.Content), "jobscheduled_success", Snackbar.LengthShort);
snackBar.Show();
}
else
{
var snackBar = Snackbar.Make(MainActivity.Instance.FindViewById(Android.Resource.Id.Content), "jobscheduled_failure", Snackbar.LengthShort);
snackBar.Show();
}
}
public void CancelJobSchedule()
{
jobScheduler.CancelAll();
}
}
Here you will find the MainActivity.Instance inside it , that's a static instance defined by self in MainActivity.
public static MainActivity Instance { set; get; }
protected override void OnCreate(Bundle savedInstanceState)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate(savedInstanceState);
Instance = this;
Xamarin.Essentials.Platform.Init(this, savedInstanceState);
global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
LoadApplication(new App());
}
Just wondering if there is an event In Xamarin for the activity class like OnStart, OnResume, OnPause etc. that gets fired when the user locks or unlocks their screen while the app is open, I've been looking for such an event in documentation etc, but I haven't been able to find it.
If there is no such event, then how can we create it?
Xamarin C# activity on screen (un)lock event
you could create a listener class to listen for android lock screen and unlock events，use broadcast to receive the state of screen.
first create a ScreenListener.cs :
public class ScreenListener
{
private Context mContext;
private ScreenBroadcastReceiver mScreenReceiver;
private static ScreenStateListener mScreenStateListener;
public ScreenListener(Context context)
{
mContext = context;
mScreenReceiver = new ScreenBroadcastReceiver();
}
/**
* screen BroadcastReceiver
*/
private class ScreenBroadcastReceiver : BroadcastReceiver
{
private String action = null;
public override void OnReceive(Context context, Intent intent)
{
action = intent.Action;
if (Intent.ActionScreenOn == action)
{ // screen on
mScreenStateListener.onScreenOn();
}
else if (Intent.ActionScreenOff == action)
{ // screen off
mScreenStateListener.onScreenOff();
}
else if (Intent.ActionUserPresent == action)
{ // unlock
mScreenStateListener.onUserPresent();
}
}
}
/**
* begin to listen screen state
*
* #param listener
*/
public void begin(ScreenStateListener listener)
{
mScreenStateListener = listener;
registerListener();
getScreenState();
}
/**
* get screen state
*/
private void getScreenState()
{
PowerManager manager = (PowerManager)mContext
.GetSystemService(Context.PowerService);
if (manager.IsScreenOn)
{
if (mScreenStateListener != null)
{
mScreenStateListener.onScreenOn();
}
}
else
{
if (mScreenStateListener != null)
{
mScreenStateListener.onScreenOff();
}
}
}
/**
* stop listen screen state
*/
public void unregisterListener()
{
mContext.UnregisterReceiver(mScreenReceiver);
}
/**
* regist screen state broadcast
*/
private void registerListener()
{
IntentFilter filter = new IntentFilter();
filter.AddAction(Intent.ActionScreenOn);
filter.AddAction(Intent.ActionScreenOff);
filter.AddAction(Intent.ActionUserPresent);
mContext.RegisterReceiver(mScreenReceiver, filter);
}
public interface ScreenStateListener
{// Returns screen status information to the caller
void onScreenOn();
void onScreenOff();
void onUserPresent();
}
}
then in the MainActivity.cs:
public class MainActivity : AppCompatActivity,ScreenStateListener
{
ScreenListener mScreenListener;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.activity_main);
mScreenListener = new ScreenListener(this);
}
protected override void OnDestroy()
{
base.OnDestroy();
mScreenListener.unregisterListener();
}
protected override void OnResume()
{
base.OnResume();
mScreenListener.begin(this);
}
public void onScreenOn()
{
Console.WriteLine("onScreenOn");
}
public void onScreenOff()
{
Console.WriteLine("onScreenOff");
}
public void onUserPresent()
{
Console.WriteLine("onUserPresent");
}
}
Here's a sample of Xamarin.Android activities lifecycle.
You can override any of the lifecycle methods like this:
protected override void OnResume() {
base.OnResume();
}
Like in native Android OnPause is fired when the system is about to put the activity into the background. OnResume is called when the activity is ready to start interacting with the user.
OnPause and OnResume can be used for your (un)lock events.
I'm creating an Android App in C# Xamarin.
Is there a way to "listen" for volume up/down key presses when an App goes into "background" mode, i.e. when a user "locks" their phone?
I've created several Service objects and made them "resident" by issuing the command 'StartCommandResult.Sticky'.
Any sample C# Xamarin code would be much appreciated.
You do not need to create a background service, just start a another task to listen the volume control. If the application do not be killed the task will run on the background.
public class MainActivity : Activity
{
private int currentVolume;
public AudioManager mAudioManager;
private int maxVolume;
private bool isDestory;
Android.Media.MediaPlayer player;
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
player = Android.Media.MediaPlayer.Create(this, Resource.Raw.SampleAudio);
SetContentView (Resource.Layout.Main);
mAudioManager = (AudioManager)GetSystemService(Context.AudioService);
maxVolume = mAudioManager.GetStreamMaxVolume(Stream.Music);
onVolumeChangeListener();
player.Start();
}
protected override void OnDestroy()
{
base.OnDestroy();
isDestory = true;
}
private Task voluemChangeTask;
public void onVolumeChangeListener()
{
currentVolume = mAudioManager.GetStreamVolume(Stream.Music);
voluemChangeTask = new Task(ChangeVolume);
voluemChangeTask.Start();
}
public void ChangeVolume()
{
while (!isDestory)
{
int count = 0;
try
{
Thread.Sleep(20);
}
catch (Exception e)
{
}
if (currentVolume < mAudioManager.GetStreamVolume(Stream.Music))
{
System.Console.WriteLine("volunm+");
count++;
currentVolume = mAudioManager.GetStreamVolume(Stream.Music);
mAudioManager.SetStreamVolume(Stream.Music, currentVolume, VolumeNotificationFlags.RemoveSoundAndVibrate);
}
if (currentVolume > mAudioManager.GetStreamVolume(Stream.Music))
{
System.Console.WriteLine("volunm-");
count++;
currentVolume = mAudioManager.GetStreamVolume(Stream.Music);
mAudioManager.SetStreamVolume(Stream.Music, currentVolume, VolumeNotificationFlags.RemoveSoundAndVibrate);
}
}
}
}
I have tested it in the real device with screen lock and got the log:
I am having this issue for a couple of days now, i did a lot of searching in the Internet, but did not find something that works in my case.
I have a service :
namespace Demo_Service_Name
{
public static class MyGlobals
{
...
public static int DurSelection;
}
class Service_Connection : Java.Lang.Object, IServiceConnection
{...}
public class Demo_Service : Service
{
public void Setup_Service(int DSel)
{
MyGlobals.DurSelection = DSel;
}
public int Get_Duration_Selection()
{
return MyGlobals.DurSelection;
}
...
}
}
and my Activity goes like this:
using Demo_Service_Name
namespace Demo_Activity
{
public class Activity1 : Activity
{
protected override void OnCreate(Bundle bundle)
{
....
ThisService = new Intent(this, typeof(Demo_Service));
if (isMyServiceRunning())
{
demoServiceConnection = new Neural_Service_Connection(this);
isBound = BindService(ThisService, demoServiceConnection, Bind.none);
int servVar = binder.GetDemoService().Get_Duration_Selection();
}
}
protected void OnStartMyService()
{
....
StartService(ThisService);
isBound = BindService(ThisService, demoServiceConnection, Bind.none);
binder.GetDemoService().Setup_Service(A_Certain_Number);
}
}
}
So what I want to do is to start the service from the activity, bind to it, pass a value, close the activity, reopen the activity and read the variable back into the activity if the service is running.
All works like it should, except that when i close the activity, the value in the service variable is reset.
What do you think am I missing?
PS. I am sure the Service.OnDestroy has not been called