Using the same onTouchEvent in various Activity

Question

I am using an onTouchEvent for in my MainActivity.class. It's working fine : if the user make a double L with the fingers, I call a fragment. I would like to use this onTouchEvent in an other Activity but I think it's dirty if I copy all my code.

Now for that I have created an implement TouchListenerImpl for that :

class TouchListenerImpl implements View.OnTouchListener {

    private boolean movingDownL, movingDownR, movingLeft, movingRight, movingSuccessL, movingSuccessR = false;
    private Point oldCoordsL, oldCoordsR, startPointL, startPointR = new Point(0, 0);
    private boolean admin_touch = false;
    private OnLTouch callback;

    void setCallback(OnLTouch c) {
        callback = c;
    }

    interface OnLTouch {
        void lTouchSuccess();
    }

    @Override
    public boolean onTouch(View v, MotionEvent event) {

        Log.d("debugTouch", "onTouch");

        int pIndexL = event.findPointerIndex(event.getPointerId(0));
        int pIndexR = 0;

        if(event.getPointerCount() > 1) pIndexR = event.findPointerIndex(event.getPointerId(1));

        if(event.getPointerCount() > 1 && event.getX(pIndexL) > event.getX(pIndexR)) {
            int tmp = pIndexR;
            pIndexR = pIndexL;
            pIndexL = tmp;
        }

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                movingDownL = true;
                movingDownR = true;
                movingSuccessL = false;
                movingSuccessR = false;

                if(event.getPointerCount() > 1) {
                    startPointR = new Point((int) event.getX(pIndexR), (int) event.getY(pIndexR));
                    oldCoordsR = new Point((int) event.getX(pIndexR), (int) event.getY(pIndexR));
                }

                startPointL = new Point((int) event.getX(pIndexL), (int) event.getY(pIndexL));
                oldCoordsL = new Point((int) event.getX(pIndexL), (int) event.getY(pIndexL));
                break;
            case MotionEvent.ACTION_MOVE:
                int downMinDistance = 300;
                int lnrInaccuracy = 10;
                int downInaccuracy = 30;
                if(event.getPointerCount() > 1) {
                    if(!movingDownR) {
                        if(Math.abs(oldCoordsR.x - event.getX(pIndexR)) < downInaccuracy &&
                                oldCoordsR.y < event.getY(pIndexR)) break;
                        if(Math.abs(oldCoordsR.y - event.getY(pIndexR)) < lnrInaccuracy &&
                                oldCoordsR.x > event.getX(pIndexR) && !movingRight) {
                            movingRight = true;
                            startPointR = new Point(new Point((int)event.getX(pIndexR), (int)event.getY(pIndexR)));
                        }
                    } else {
                        if (Math.abs(oldCoordsR.x - event.getX(pIndexR)) > downInaccuracy ||
                                oldCoordsR.y < event.getY(pIndexR)) {
                            movingDownR = false;
                            break;
                        } else if(findDistance(startPointR,
                                new Point((int)event.getX(pIndexR), (int)event.getY(pIndexR))) >= downMinDistance){
                            movingDownR = false;
                        }
                    }
                }

                if(!movingDownL) {
                    if(Math.abs(oldCoordsL.x - event.getX(pIndexL)) < downInaccuracy &&
                            oldCoordsL.y < event.getY(pIndexL)) break;
                    if(Math.abs(oldCoordsL.y - event.getY(pIndexL)) < lnrInaccuracy &&
                            oldCoordsL.x < event.getX(pIndexL) && !movingLeft) {
                        movingLeft = true;
                        startPointL = new Point(new Point((int)event.getX(pIndexL), (int)event.getY(pIndexL)));
                    }
                }else {
                    if (Math.abs(oldCoordsL.x - event.getX(pIndexL)) > downInaccuracy ||
                            oldCoordsL.y > event.getY(pIndexL)) {
                        movingDownL = false;
                        break;
                    } else if(findDistance(startPointL,
                            new Point((int)event.getX(pIndexL), (int)event.getY(pIndexL))) >= downMinDistance){
                        movingDownL = false;
                    }
                }

                int lnrMinDistance = 50;
                if(movingLeft) {
                    if (Math.abs(oldCoordsL.y - event.getY(pIndexL)) > lnrInaccuracy ||
                            oldCoordsL.x > event.getX(pIndexL)) {
                        movingLeft = false;
                        break;
                    } else if(findDistance(startPointL,
                            new Point((int)event.getX(pIndexL), (int)event.getY(pIndexL))) >= lnrMinDistance) {
                        movingLeft = false;
                        movingSuccessL = true;
                    }
                }

                if(movingRight) {
                    if (Math.abs(oldCoordsR.y - event.getY(pIndexR)) > lnrInaccuracy ||
                            oldCoordsR.x < event.getX(pIndexR)) {
                        movingRight = false;
                        break;
                    } else if(findDistance(startPointR,
                            new Point((int)event.getX(pIndexR), (int)event.getY(pIndexR))) >= lnrMinDistance) {
                        movingRight = false;
                        movingSuccessR = true;
                    }
                }

                if(movingSuccessL && movingSuccessR) {
                    if (!admin_touch)
                    {
                        admin_touch = true;

                        if (callback != null)
                            callback.lTouchSuccess();
                    }
                }

                oldCoordsL = new Point((int)event.getX(pIndexL), (int)event.getY(pIndexL));
                oldCoordsR = new Point((int)event.getX(pIndexR), (int)event.getY(pIndexR));

                break;
            case MotionEvent.ACTION_UP:
                movingDownL = false;
                movingDownR = false;
                movingLeft = false;
                movingRight = false;
                break;
            default:
                return false;
        }
        return true;
    }

    private double findDistance(Point p1, Point p2) {
        return Math.sqrt(Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2));
    }
}

In my Activity, I call the implement like this :

public class MainActivity extends AppCompatActivity implements View.OnTouchListener {
    TouchListenerImpl imp = new TouchListenerImpl();

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

        setContentView(R.layout.activity_main);

        imp.setCallback(new TouchListenerImpl.OnLTouch() {
            @Override
            public void lTouchSuccess() {
                Log.d("debugTouch", "WORKING !");         
            }
        });
    }


    @Override
    public boolean onTouch(View v, MotionEvent event) {
        Log.d("debugTouch", "onTouch");
        return imp.onTouch(v, event);
    }
}

The problem is I never enter in my logs. It's not working at all...

Answer 1

You could use @DrilonBlakqori solution with little modification.

Make a separate class containing common code but use a callback to make View visible.

class TouchListenerImpl implements OnTouchListener {
    private OnLTouch callback;
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        // all your code
        ...
            if (callback != null)
                callback.lTouchSuccess();
        ...
    }

    void setCallback(OnLTouch c) {
        callback = c;
    }

    interface OnLTouch {
        void lTouchSuccess();
    }
}

In your MainActivity, create a new instance of TouchListenerImpl and setCallback like

TouchListenerImpl imp = new TouchListenerImpl();
imp.setCallback(new OnLTouch() {
    public void lTouchSuccess() {
        frameLayoutAdmin.setVisibility(View.VISIBLE);
        getSupportFragmentManager().beginTransaction()
            .replace(R.id.framelayout_admin,new AdminLoginFragment())
            .commit();
        img_close.setVisibility(View.VISIBLE);
    }
});

And in MainActivity, the View on which you want to detect the double L on that View set this listener on that View.

view.setOnTouchListener(imp);

I assume you want to detect double L on the main layout. For that you can do

findViewById(R.id.mylayout).setOnTouchListener(imp);

I hope this solves your problem.