dispatchTouchEvent in Fragment in Android

Question

I am trying to get swipe up and swipe down gestures working in Fragment. The same is working fine with activity. In Fragment, I have an issue with dispatchTouchEvent. How d

Answer 1

You must dispatchTouchEvent in your parent activity like that Add this code to parent activity:

private List<MyOnTouchListener> onTouchListeners;
@Override
protected void onCreate(Bundle savedInstanceState) {
    if(onTouchListeners==null)
    {
        onTouchListeners=new ArrayList<>();
    }
}
public void registerMyOnTouchListener(MyOnTouchListener listener){
    onTouchListeners.add(listener);
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    for(MyOnTouchListener listener:onTouchListeners)
        listener.onTouch(ev);
    return super.dispatchTouchEvent(ev);
}
public interface MyOnTouchListener {
    public void onTouch(MotionEvent ev);
}

OnSwipeTouchListener:

public class OnSwipeTouchListener{

private final GestureDetector gestureDetector;

public OnSwipeTouchListener (Context ctx){
    gestureDetector = new GestureDetector(ctx, new GestureListener());
}

private final class GestureListener extends SimpleOnGestureListener {
     //override touch methode like ondown ... 
     //and call the impelinfragment()
}
public void impelinfragment(){
 //this method impelment in fragment
}
//by calling this mehod pass touch to detector
public void onTouch( MotionEvent event) {
     gestureDetector.onTouchEvent(event);
}

And add this code to fragment you like to dispach touch in it:

//ontouch listenr
MainActivity.MyOnTouchListener onTouchListener;
private OnSwipeTouchListener touchListener=new OnSwipeTouchListener(getActivity()) {
    public void impelinfragment(){
 //do what you want:D
}

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

    //setting for on touch listener
    ((MainActivity)getActivity()).registerMyOnTouchListener(new MainActivity.MyOnTouchListener() {
        @Override
        public void onTouch(MotionEvent ev) {
            LocalUtil.showToast("i got it ");
            touchListener.onTouch(ev);
        }
    });
}

I use this method to get all swipe to right or left event in fragment without conflicting with other elem in page .unlike rax answer

Answer 2

If your goal is to detect/handle swipe, add touch event listener on the fragment's view after creating the view.

Answer 3

Fragments are attached to activity, not replacing activity. So you can still override dispatchTouchEvent in your fragment parent activity and pass any actions from there.

For example:

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    MyFragment myFragment = (MyFragment) getFragmentManager().findFragmentByTag("MY_FRAGMENT_TAG");
    myFragment.doSomething();
    return super.dispatchTouchEvent(ev);
}