Cusom event attributes in android bindings app:onMyEvent

Question

Is there any way to wire up custom onSomeEventListener to the attribute using binding library? Examples provided for onClick are simple and they all use 'on' prefix and single-method interface listeners, and what about 'add' prefix and more complicated scenarios?

Imagine I want to use custom wire up logic on RecyclerView.addOnItemTouchListener, determining the child view was touched from SimpleOnItemTouchListener.onTouchEvent and passing it to my view model, how can I achieve this?

I want to end up with something like this:

<RecyclerView
    app:onItemTouch="@{handlers::recyclerViewOnItemTouch}"/>

public class Handlers {
    public void recyclerViewOnItemTouch(View view) { ... }
}

Is there something similar to approach when notifying binding framework about your custom property update using BindingAdapter and InverseBindingListener?

@BindingAdapter("app:someAttrChanged") 
public static void setListener(View view, InverseBindingListener listener)

Answer 1

After some investigation and trial and error, I found a solution.

Of course, you'll need to activate the Binding in your Activity or Fragment and set an instance of the ClickHandler to it, and have a variable for it in your xml for the ClickHandler. Assuming that you already know that, I'll continue:

One part of the magic is using app:addOnItemTouchListener for the RecyclerView:

<android.support.v7.widget.RecyclerView
    android:id="@+id/rec_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:addOnItemTouchListener="@{clickHandler.touchListener}"/>

The other part is the ClickHandler.class:

public class ClickHandler {

    public RecyclerView.OnItemTouchListener touchListener;

    public ClickHandler(){
        //initialize the instance of your touchListener in the constructor
        touchListener = new RecyclerView.SimpleOnItemTouchListener(){
            @Override
            public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e)     {
                //allow clicks
                return true;
            }

            @Override
                public void onTouchEvent(RecyclerView rv, MotionEvent e) {
                //check if it is working / check if we get the touch event:
                Log.d("onTouchEvent", "RecView: " + rv.getId() + "\nMotionEvent: "+ e.getAction());
            }
        };
    }

    /* last but not least: a method which returns the touchlistener. 
       You can rename the method, but don't forget to rename the attribute in the xml, too. */
    public RecyclerView.OnItemTouchListener touchListener(){
        return touchListener;
    }
}