How to detect a flip / home press from a service such as a chat service?

Question

I was looking through several stackoverflow questions to find out how I can listen to the return button in a service using the window manager. Most of the answers suggest that this is impossible, but I see that the messenger does it very well.

How does the sender of the message handle the "Send" button on the main chat service? (Or am I completely wrong and they are not a service using window manager?)

Answer 1

, , ViewGroup, . :

public class BackButtonAwareLinearLayout extends LinearLayout {

    public interface BackButtonListener {
        void onBackButtonPressed();
    }

    @Nullable
    private BackButtonListener mListener;

    public BackButtonAwareLinearLayout(Context context) {
        super(context);
    }

    public BackButtonAwareLinearLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public BackButtonAwareLinearLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public void setBackButtonListener(@Nullable BackButtonListener listener) {
        mListener = listener;
    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        if (event != null && event.getKeyCode() == KeyEvent.KEYCODE_BACK
                && mListener != null) {
            mListener.onBackButtonPressed();
            return true;
        }
        return super.dispatchKeyEvent(event);
    }
}

, KeyEvent - . xml ( chat_head_container.xml):

<?xml version="1.0" encoding="utf-8"?>
<com.pablo432.myapplication.BackButtonAwareLinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="48sp"
        android:text="Hello, world!"
        android:textColor="#000"
        android:background="#f5f5f5"
        android:gravity="center"/>

</com.pablo432.myapplication.BackButtonAwareLinearLayout>

, WindowManager (, , , , ):

public class ChatHeadService extends Service
        implements BackButtonAwareLinearLayout.BackButtonListener {

    private WindowManager mWindowManager;
    private BackButtonAwareLinearLayout mRootContainer;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mWindowManager = (WindowManager) getSystemService(Context.WINDOW_SERVICE);
        LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mRootContainer = (BackButtonAwareLinearLayout) inflater.inflate(
                R.layout.chat_head_container, null, false);
        mRootContainer.setBackButtonListener(this);

        WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.MATCH_PARENT,
                WindowManager.LayoutParams.MATCH_PARENT,
                WindowManager.LayoutParams.TYPE_PHONE,
                WindowManager.LayoutParams.FLAG_FULLSCREEN,
                PixelFormat.TRANSPARENT);

        mWindowManager.addView(mRootContainer, layoutParams);
    }

    @Override
    public void onBackButtonPressed() {
        mRootContainer.setBackButtonListener(null);
        mWindowManager.removeView(mRootContainer);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (mRootContainer != null) mWindowManager.removeView(mRootContainer);
    }
}

, BackButtonAwareLinearLayout , .

, . fooobar.com/questions/235402/... fooobar.com/questions/1015772/... - - + fooobar.com/questions/30766/..., (, FLAG_NOT_FOCUSABLE WindowManager.LayoutParams).

, -, startService, AndroidManifest.xml SYSTEM_ALERT_WINDOW.