Immagine tonda che appare a intervalli prestabiliti

Ecco un'immagine circolare che appare a intervalli di tempo prestabiliti.

MainActivity:

package com.antonello.tavolaccio5;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.SystemClock;
import android.provider.Settings;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.RelativeLayout;

public class MainActivity extends AppCompatActivity {

    Button bttCancel;
    Button button;
    RelativeLayout mainLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mainLayout=(RelativeLayout)findViewById(R.id.mainLayout);
        button=(Button)findViewById(R.id.button);
        bttCancel=(Button)findViewById(R.id.button2);




        button.setOnClickListener(new Button.OnClickListener(){

            @Override
            public void onClick(View v) {
                if(Build.VERSION.SDK_INT>=23 && !Settings.canDrawOverlays(getApplicationContext())){
                    Intent intent=new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, Uri.parse("package:"+getPackageName()));
                    startActivityForResult(intent,0);
                }else {
                    AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
                    Intent intent = new Intent(getApplicationContext(), Servizio.class);
                    PendingIntent pendingIntent = PendingIntent.getService(getApplicationContext(), 0, intent, 0);
                    alarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime() + 1000 * 5,
                            pendingIntent);
                }
            }
        });

        bttCancel.setOnClickListener(new Button.OnClickListener(){

            @Override
            public void onClick(View v) {

                AlarmManager alarmManager=(AlarmManager)getSystemService(ALARM_SERVICE);
                Intent intent=new Intent(getApplicationContext(),Servizio.class);
                PendingIntent pendingIntent=PendingIntent.getService(getApplicationContext(),0,intent,0);
                alarmManager.cancel(pendingIntent);
                if(pendingIntent!=null)pendingIntent.cancel();
            }
        });

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data){

        if(Build.VERSION.SDK_INT>=23 && Settings.canDrawOverlays(getApplicationContext())){
            AlarmManager alarmManager=(AlarmManager)getSystemService(ALARM_SERVICE);
            Intent intent=new Intent(getApplicationContext(),Servizio.class);
            PendingIntent pendingIntent=PendingIntent.getService(getApplicationContext(),0,intent,0);
            alarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime()+1000*5,
                    pendingIntent);
        }
    }
}

Servizio.java

package com.antonello.tavolaccio5;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.graphics.PixelFormat;
import android.os.IBinder;
import android.os.SystemClock;
import android.support.annotation.Nullable;
import android.view.View;
import android.view.WindowManager;

/**
 * Created by Antonello on 19/05/2017.
 */

public class Servizio extends Service {

    RoundedImage roundedImage;
    WindowManager.LayoutParams wParams;
    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId){
        final WindowManager windowManager=(WindowManager)getSystemService(WINDOW_SERVICE);

        wParams=new WindowManager.LayoutParams(
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.WRAP_CONTENT,
                WindowManager.LayoutParams.TYPE_PHONE,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT
        );

        roundedImage = new RoundedImage(this, BitmapFactory.decodeResource(getResources(),R.drawable.scrofalo),100);
        roundedImage.setOnClickListener(new View.OnClickListener(){

            @Override
            public void onClick(View v) {
                windowManager.removeView(v);
                //roundedImage=null;
                AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
                Intent intent = new Intent(getApplicationContext(), Servizio.class);
                PendingIntent pendingIntent = PendingIntent.getService(getApplicationContext(), 0, intent, 0);
                alarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, SystemClock.elapsedRealtime() + 1000 * 5,
                        pendingIntent);

            }
        });

        windowManager.addView(roundedImage,wParams);

        stopSelf();
        return START_NOT_STICKY;
    }



}

RoundedImage.java

package com.antonello.tavolaccio5;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;


/**
 * Created by Antonello on 19/05/2017.
 */

public class RoundedImage extends android.support.v7.widget.AppCompatImageView {

    private Bitmap figura;
    private int radius;

    public RoundedImage(Context context, Bitmap figura, int radius){
        super(context);

        this.figura=figura;
        this.radius=radius;

        Bitmap bitmap=Bitmap.createBitmap(radius,radius,Bitmap.Config.ARGB_8888);

        Paint paint=new Paint();
        Canvas canvas=new Canvas(bitmap);
        canvas.drawCircle(bitmap.getWidth()/2,bitmap.getHeight()/2,bitmap.getWidth()/2,paint);

        Rect fromRect=new Rect(0,0,figura.getWidth(),figura.getHeight());
        Rect toRect=new Rect(0,0,bitmap.getWidth(),bitmap.getHeight());
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

        canvas.drawBitmap(figura,fromRect,toRect,paint);

        setImageBitmap(bitmap);

    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mainLayout"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.antonello.tavolaccio5.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:id="@+id/textView" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/textView"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="99dp"
        android:text="Button" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/button"
        android:layout_alignStart="@+id/button"
        android:layout_below="@+id/button"
        android:layout_marginTop="120dp"
        android:text="Button" />

</RelativeLayout>