android - SYSTEM_ALERT_WINDOW PERMISSION on API 26 not working as expected. Permission denied for window type 2002

Question

I am using overlay permission to display certain information in my app. Running it on API 23 - 25 it works fine (asking for permission, granting, etc. according to

Unable to add window android.view.ViewRoot$W@44da9bc0 -- permission denied for this window type ). (Many thanks to ceph3us!)

Trying the same on API 26 I am getting an error, basically "permission denied for window type 2002" when calling

windowManager.addView(frameLayout, params);

Did Google change the way, overlay works? Any idea, how to get my text as an overlay onto the screen in Android 8 (Oreo), API 26? Thanks for your ideas!

This is the error-log:

08-24 16:41:56.730 2615-2615/net.zwittscha.testoverlay E/AndroidRuntime: FATAL EXCEPTION: main
Process: net.zwittscha.testoverlay, PID: 2615
java.lang.RuntimeException: Unable to start activity ComponentInfo{net.zwittscha.testoverlay/net.zwittscha.testoverlay.MainActivity}: 
                android.view.WindowManager$BadTokenException: Unable to add window android.view.ViewRootImpl$W@6fa0089 -- 
                permission denied for window type 2002
 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
 at android.app.ActivityThread.-wrap11(Unknown Source:0)
 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
 at android.os.Handler.dispatchMessage(Handler.java:105)
 at android.os.Looper.loop(Looper.java:164)
 at android.app.ActivityThread.main(ActivityThread.java:6541)
 at java.lang.reflect.Method.invoke(Native Method)
 at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
            Caused by: android.view.WindowManager$BadTokenException: 
            Unable to add window android.view.ViewRootImpl$W@6fa0089 -- 
            permission denied for window type 2002
 at android.view.ViewRootImpl.setView(ViewRootImpl.java:789)
 at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:356)
 at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:92)
 at net.zwittscha.testoverlay.MainActivity.createOnTopView(MainActivity.java:46)
 at net.zwittscha.testoverlay.MainActivity.checkDrawOverlayPermission(MainActivity.java:66)
 at net.zwittscha.testoverlay.MainActivity.onCreate(MainActivity.java:28)
 at android.app.Activity.performCreate(Activity.java:6975)
 at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
 at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)?
 at android.app.ActivityThread.-wrap11(Unknown Source:0)?
 at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)?
 at android.os.Handler.dispatchMessage(Handler.java:105)?
 at android.os.Looper.loop(Looper.java:164)?
 at android.app.ActivityThread.main(ActivityThread.java:6541)?
 at java.lang.reflect.Method.invoke(Native Method)?
 at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)?
 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)?

In my Manifest, I have:

<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

<uses-permission android:name="android.permission.ACTION_MANAGE_OVERLAY_PERMISSION"/>

This is my MainActivity:

    public class MainActivity extends AppCompatActivity {

DrawView dv;
FrameLayout frameLayout;
WindowManager windowManager;
LayoutInflater layoutInflater;
/** code to post/handler request for permission */
public final static int REQUEST_CODE = 1234;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    checkDrawOverlayPermission();
}

public void createOnTopView() {

    WindowManager.LayoutParams params = new WindowManager.LayoutParams(
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.WRAP_CONTENT,
            WindowManager.LayoutParams.TYPE_PHONE,
            WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE,
            PixelFormat.TRANSLUCENT);
    params.gravity = Gravity.CENTER;

    if (frameLayout == null) frameLayout = new FrameLayout(getApplicationContext());
    if (dv == null) dv = new DrawView(getApplicationContext());

    windowManager = (WindowManager)
            getApplicationContext().getSystemService(Context.WINDOW_SERVICE);
    windowManager.addView(frameLayout, params);
    windowManager.addView(dv, params);

    layoutInflater = (LayoutInflater)
            getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    // Here is the place where you can inject whatever layout you want.
    layoutInflater.inflate(R.layout.activity_main, frameLayout);
}

public void checkDrawOverlayPermission() {
    /* check if we already  have permission to draw over other apps */
    if (android.os.Build.VERSION.SDK_INT > 22) {
        if (!Settings.canDrawOverlays(this)) {
        /* if not construct intent to request permission */
            Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION,
                    Uri.parse("package:" + getPackageName()));
        /* request permission via start activity for result */
            startActivityForResult(intent, REQUEST_CODE);
        }
        else {
            createOnTopView();
        }
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode,  Intent data) {
    /* check if received result code
     is equal our requested code for draw permission  */
    if (requestCode == REQUEST_CODE && android.os.Build.VERSION.SDK_INT > 22) {
   /* if so check once again if we have permission */
        if (Settings.canDrawOverlays(this)) {
            createOnTopView();
        }
    }
}
}

And this is the DrawView:

    public class DrawView extends View {

int w;
int h;
int r;
float screenFactor;
TextPaint startTextPaint;

public DrawView(Context activity) {
    super(activity);
}

@Override
protected void onSizeChanged(int width, int height, int oldw, int oldh) {

        w = width;
        h = height;
        r = w / 2;

    screenFactor = (r / 160f);

    if (startTextPaint == null) startTextPaint = new TextPaint();

    startTextPaint.setTextSize(100);
    startTextPaint.setTextAlign(Paint.Align.CENTER);
    startTextPaint.setTypeface(Typeface.create("Roboto Condensed", Typeface.BOLD));

    super.onSizeChanged(w, h, oldw, oldh);
}

@Override
protected void onDraw(Canvas canvas) {

        startTextPaint.setARGB(255,255,0,0);
        canvas.drawText("Test", w / 2, h / 2, startTextPaint);
}
}

Answer 1

According to the documentation on Android 8.0 Behavior Changes for apps targeting Android 8.0:

Apps that use the SYSTEM_ALERT_WINDOW permission can no longer use the following window types to display alert windows above other apps and system windows:

TYPE_PHONE
TYPE_PRIORITY_PHONE
TYPE_SYSTEM_ALERT
TYPE_SYSTEM_OVERLAY
TYPE_SYSTEM_ERROR

Instead, apps must use a new window type called TYPE_APPLICATION_OVERLAY.

So your app could target some lower version. In this case, your alert window will ...

always appear beneath the windows that use the TYPE_APPLICATION_OVERLAY window type. If an app targets Android 8.0 (API level 26), the app uses the TYPE_APPLICATION_OVERLAY window type to display alert windows.

(quoted from the same source)