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Full source code can be found : https://github.com/Ali-Rezaei/Contacts/tree/QuickHideBehavior

I have following CoordinatorLayout behavior class :

public abstract class QuickHideBehavior extends CoordinatorLayout.Behavior<View> {

    private static final int DIRECTION_UP = 1;
    private static final int DIRECTION_DOWN = -1;

    /* Tracking direction of user motion */
    private int mScrollingDirection;

    /* Tracking last threshold crossed */
    private int mScrollTrigger;

    /* Accumulated scroll distance */
    private int mScrollDistance;

    /* Distance threshold to trigger animation */
    private int mScrollThreshold;

    private ObjectAnimator mAnimator;

    protected View mRecyclerView;

    protected abstract float getTargetHideValue(ViewGroup parent, View target);

    protected abstract void setMarginUpScroll();

    protected abstract void setMarginDownScroll();

    //Required to instantiate as a default behavior
    @SuppressWarnings("unused")
    public QuickHideBehavior() {
    }

    //Required to attach behavior via XML
    @SuppressWarnings("unused")
    public QuickHideBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray a = context.getTheme()
                .obtainStyledAttributes(new int[] {R.attr.actionBarSize});
        //Use half the standard action bar height
        mScrollThreshold = a.getDimensionPixelSize(0, 0) / 2;
        a.recycle();
    }

    @Override
    public boolean onLayoutChild(@NonNull CoordinatorLayout parent, @NonNull View child,
                                 int layoutDirection) {
        if (mRecyclerView == null) {
            mRecyclerView = parent.findViewById(R.id.recyclerView);
        }
        return super.onLayoutChild(parent, child, layoutDirection);
    }

    //Called before a nested scroll event. Return true to declare interest
    @Override
    public boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout,
                                       @NonNull View child, @NonNull View directTargetChild,
                                       @NonNull View target, int nestedScrollAxes, int type) {
        //We have to declare interest in the scroll to receive further events
        return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0;
    }

    //Called before the scrolling child consumes the event
    // We can steal all/part of the event by filling in the consumed array
    @Override
    public void onNestedPreScroll(CoordinatorLayout coordinatorLayout,
                                  View child, View target,
                                  int dx, int dy,
                                  int[] consumed) {
        //Determine direction changes here
        if (dy > 0 && mScrollingDirection != DIRECTION_UP) {
            mScrollingDirection = DIRECTION_UP;
            mScrollDistance = 0;
        } else if (dy < 0 && mScrollingDirection != DIRECTION_DOWN) {
            mScrollingDirection = DIRECTION_DOWN;
            mScrollDistance = 0;
        }
    }

    //Called after the scrolling child consumes the event, with amount consumed
    @Override
    public void onNestedScroll(CoordinatorLayout coordinatorLayout,
                               View child, View target,
                               int dxConsumed, int dyConsumed,
                               int dxUnconsumed, int dyUnconsumed) {
        //Consumed distance is the actual distance traveled by the scrolling view
        mScrollDistance += dyConsumed;
        if (mScrollDistance > mScrollThreshold
                && mScrollTrigger != DIRECTION_UP) {
            //Hide the target view
            mScrollTrigger = DIRECTION_UP;
            restartAnimator(child, getTargetHideValue(coordinatorLayout, child));
        } else if (mScrollDistance < -mScrollThreshold
                && mScrollTrigger != DIRECTION_DOWN) {
            //Return the target view
            mScrollTrigger = DIRECTION_DOWN;
            restartAnimator(child, 0f);
        }
    }

    //Called after the scrolling child handles the fling
    @Override
    public boolean onNestedFling(@NonNull CoordinatorLayout coordinatorLayout,
                                 @NonNull View child, @NonNull View target, float velocityX,
                                 float velocityY, boolean consumed) {
        //We only care when the target view is already handling the fling
        if (consumed) {
            if (velocityY > 0 && mScrollTrigger != DIRECTION_UP) {
                mScrollTrigger = DIRECTION_UP;
                restartAnimator(child, getTargetHideValue(coordinatorLayout, child));
                setMarginUpScroll();

            } else if (velocityY < 0 && mScrollTrigger != DIRECTION_DOWN) {
                mScrollTrigger = DIRECTION_DOWN;
                restartAnimator(child, 0f);
                setMarginDownScroll();
            }
        }
        return false;
    }
}
I want to hide/show following layout using above CoordinatorLayout behavior :

<RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_behavior=".behavior.QuickHideBottomBarBehavior">

        <com.sample.android.contact.widget.ListenableTabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="48dp"
            android:layout_alignParentBottom="true"
            android:background="@drawable/rectangle_shape"
            app:tabIndicatorHeight="2dp"
            app:tabSelectedTextColor="@color/color1" />

        <ImageView
            android:id="@+id/triangle"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_above="@+id/tab_layout"
            android:layout_marginBottom="@dimen/dimen_triangle_bottom_margin"
            android:src="@drawable/triangle_shape"
            tools:ignore="ContentDescription" />

    </RelativeLayout>
For some reason onNestedScroll never get called. But it is working very well for the appBarLayout:

<com.google.android.material.appbar.AppBarLayout
            android:id="@+id/appBarLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_behavior=".behavior.QuickHideAppBarBehavior"
            app:showData="@{vm.liveData}">

Why onNestedPreScroll get called but onNestedScroll never get called for FooterLayout which is a RelativeLayout in my case?