Creating custom LockScreen in android

Question

I am developing custom lockscreen app.its working fine in below 4.0 but above 4.0,when we press home button the app stops.is there any solution for this no apps will stop when pressing home button untill unlocking the screen.(like go locker app)

Answer 1

Another way to develop a LockScreen App is by using Views, let me explain it.

First of all you can "disable" in some devices the System lock screen by disabling the KEYGUARD:

((KeyguardManager)getSystemService(Activity.KEYGUARD_SERVICE)).newKeyguardLock("IN").disableKeyguard();

You should put this line of code in your Service.

After that you can launch an activity every time the screen goes off:

public class AutoStart extends BroadcastReceiver {

    public void onReceive(Context arg0, Intent arg1) {
        if(arg1.getAction().equals("android.intent.action.SCREEN_OFF")) {
            Intent localIntent = new Intent(arg0, LockScreen.class);
            localIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            localIntent.addFlags(WindowManager.LayoutParams.TYPE_SYSTEM_ERROR);
            arg0.startActivity(localIntent);
        }
    }
}

If you read the documentation for WindowManager.LayoutParams.TYPE_SYSTEM_ERROR it explains that is a type of internal system error windows, appear on top of everything they can. In multiuser systems shows only on the owning user's window.

So now you have an activity on top of everything, but a press in HOME button will exit the activity.

Here is where the Views make their appearance. You can inflate a view from a layout resource and add it to the WindowManager as a TYPE_SYSTEM_ERROR, so will be on top of everything. And since you can control when to remove this View, the best place is in onDestroy of your Activity, because pressing the HOME button will only pause your activity, and the view will still be visible.

public WindowManager winManager;
public RelativeLayout wrapperView;

 @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
 WindowManager.LayoutParams localLayoutParams = new WindowManager.LayoutParams( WindowManager.LayoutParams.TYPE_SYSTEM_ERROR,
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE|
                        WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL|
                        WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN,
                PixelFormat.TRANSLUCENT);
        this.winManager = ((WindowManager)getApplicationContext().getSystemService(WINDOW_SERVICE));
        this.wrapperView = new RelativeLayout(getBaseContext());
        getWindow().setAttributes(localLayoutParams);
        View.inflate(this, R.layout.lock_screen, this.wrapperView);
        this.winManager.addView(this.wrapperView, localLayoutParams);
}

 public void onDestroy()
    {
        this.winManager.removeView(this.wrapperView);
        this.wrapperView.removeAllViews();
        super.onDestroy();
    }

To avoid the notification bar of showing I added the flags FLAG_NOT_FOCUSABLE | FLAG_NOT_TOUCH_MODAL | FLAG_LAYOUT_IN_SCREEN to consume all pointer events.

Not forget to add these two lines to your manifest:

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

From here you just need to add the logic of your Lock Screen app to let the user use his smartphone :)