Binoy Babu Binoy Babu - 6 months ago 38
Java Question

Passing MotionEvents from RecyclerView.OnItemTouchListener to GestureDetectorCompat

I have a Fragment that implemets RecyclerView.OnItemTouchListener. How do I pass click and long-click motion events only from the RecyclerView to the GestureDetectorCompat. That is I mean I only want to handle clicks and long-clicks, rest of the events should be handled by the RecyclerView as it would happen normally. How can I set this up?

public class MyFragment extends Fragment implements RecyclerView.OnItemTouchListener,
GestureDetector.OnGestureListener {

protected RecyclerView recyclerView;
protected RecyclerView.Adapter adapter;
protected LinearLayoutManager layoutManager;
private GestureDetectorCompat detector;

public MyFragment() {
// Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.myfrag, container, false);

recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerview);

layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
recyclerView.addOnItemTouchListener(this);

adapter = new MyAdapter(myData));
recyclerView.setAdapter(adapter);
return rootView;
}


@Override
public boolean onDown(MotionEvent e) {
return false;
}

@Override
public void onShowPress(MotionEvent e) {

}

@Override
public boolean onSingleTapUp(MotionEvent e) {
return false;
}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
return false;
}

@Override
public void onLongPress(MotionEvent e) {

}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
return false;
}

@Override
public boolean onInterceptTouchEvent(RecyclerView recyclerView, MotionEvent event) {
return false;
}

@Override
public void onTouchEvent(RecyclerView recyclerView, MotionEvent event) {

}
}

Answer

You have to initialize GestureDetectorCompat in onCreateView() method:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.myfrag, container, false);

    detector = new GestureDetectorCompat(getActivity(), new RecyclerViewOnGestureListener());

    recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerview);

    layoutManager = new LinearLayoutManager(getActivity());
    recyclerView.setLayoutManager(layoutManager);
    recyclerView.addOnItemTouchListener(this);

    adapter = new MyAdapter(myData));
    recyclerView.setAdapter(adapter);
    return rootView;
}

RecyclerViewOnGestureListener is your own inner class extending SimpleOnGestureListener (that provides empty implementation of OnGestureListener methods)

private class RecyclerViewOnGestureListener extends SimpleOnGestureListener {

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        View view = recyclerView.findChildViewUnder(e.getX(), e.getY());
        int position = recyclerView.getChildPosition(view);

        // handle single tap

        return super.onSingleTapConfirmed(e);
    }

    public void onLongPress(MotionEvent e) {
        View view = recyclerView.findChildViewUnder(e.getX(), e.getY());
        int position = recyclerView.getChildPosition(view);

        // handle long press

        super.onLongPress(e);
    }
}

Now look at line (from onCreateView() method):

recyclerView.addOnItemTouchListener(this);

In our case 'this' is OnItemTouchListener containing two methods we need to implement:

@Override
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
    detector.onTouchEvent(e);
    return false;
}

@Override
public void onTouchEvent(RecyclerView rv, MotionEvent e) {
}

Here is an explanation what these methods mean: https://developer.android.com/reference/android/support/v7/widget/RecyclerView.OnItemTouchListener.html

It's all you need to handle single tap and long press events from RecyclerView.