Handling scroll state to hide FAB in Fragment

Question

I have a FAB that is tied with a ViewPager that when clicked opens a fragment and hides the FAB, but when I horizontally scroll within the fragment the FAB reappears. So I decided to handle scroll state of the ViewPager by calling addOnPageChangeListener and use a custom ViewPager to set the scroll state (setSwipeEnabled). This is the problem. Either I get the fragment to not scroll but neither will the ViewPager on fragment exit or I get the buttons reappearing. The conditional I am trying to achieve is (if newly opened fragment by FAB is !null don't scroll, otherwise, scroll). Any help appreciated! Code:

HomeActivity

    mViewPager = findViewById(R.id.viewPager);
    mViewPager.setSwipeEnabled(true);

    ...

    mFAB = findViewById(R.id.mainFab);

    mViewPager.addOnPageChangeListener(new CustomViewPager.OnPageChangeListener() {

        Fragment fragment = null;

        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        }

        @Override
        public void onPageSelected(final int position) {

            if(position == 2){
                mFAB.hide();
            }else{
                mFAB.show();
            }


            switch (position){
                case 0:
                    mFAB.setImageResource(R.drawable.ic_handshake_white_54dp);
                    mFAB.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {



                            mActionBar.setTitle("New Package");

                            mFAB.hide();

                            fragment = new AddPackageFragment();

                            mFragmentManager.beginTransaction().add(R.id.contentFrame,fragment).addToBackStack("HomeFrag").commit();

                            //Condition I can't get to work
                            if(fragment != null){
                                mViewPager.setSwipeEnabled(false);
                            }else{
                                mViewPager.setSwipeEnabled(true);
                            }

                        }

                    });

                    break;
                case 1:
                    mFAB.setImageResource(R.drawable.ic_mail_outline_24dp);
                    mFAB.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {

                            mFAB.hide();

                            mActionBar.setTitle("New Message");

                            fragment = new NewMessageFragment();

                            mFragmentManager.beginTransaction().add(R.id.contentFrame,fragment).addToBackStack(null).commit();

                        }
                    });
                    break;
                case 2:

                    mFAB.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {

                            fragment = new DialogEditRequestFragment();

                            mFragmentManager.beginTransaction().replace(R.id.contentFrame,fragment).addToBackStack(null).commit();

                        }
                    });
                    break;

            }

        }

        @Override
        public void onPageScrollStateChanged(int state) {
            //Animate fab
            if(state == SCROLL_STATE_DRAGGING){
                mFAB.hide();
            }

            if(state == SCROLL_STATE_SETTLING){
                mFAB.show();
            }
        }
    });

}

CustomViewPager

    public class CustomViewPager extends ViewPager {

private boolean swipePageEnabled;

public CustomViewPager(Context context, AttributeSet attrs) {
    super(context, attrs);
    this.swipePageEnabled = false; // By default swiping is disabled
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    return this.swipePageEnabled && super.onTouchEvent(event);

}

@Override
public boolean onInterceptTouchEvent(MotionEvent event) {
    return this.swipePageEnabled && super.onInterceptTouchEvent(event);

}

@Override
public boolean executeKeyEvent(KeyEvent event) {
    return this.swipePageEnabled && super.executeKeyEvent(event);
}

public void setSwipeEnabled(boolean enabled) {
    this.swipePageEnabled = enabled;
}

public boolean isSwipeEnabled(){
    return swipePageEnabled;
}

Answer 1

So I figured it out! All it took was a boolean interface that checks if fragment is visible. Sounds so simple but sometimes you just need sleep.

HomeActivity

    @Override
public void onFragmentVisible(boolean isVisible) {
    if(!isVisible){
        mViewPager.setSwipeEnabled(true);
        mFAB.show();
    }
}

Fragment

    mCloseBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            mFragmentVisibilityListener.onFragmentVisible(false);
            mActionBarListener.onActionBarListener(R.string.app_name);
            getFragmentManager().popBackStack();
        }
    });

  @Override
public void onAttach(Context context) {
    super.onAttach(context);

    try{
        mFragmentVisibilityListener = (OnFragmentInteractionListener) context;
        mActionBarListener = (OnFragmentInteractionListener) context;
    }catch (ClassCastException e){
        throw new ClassCastException(context.toString() + "must implement OnFragmentInteraction Listener");
    }
}

    @Override
public void onDetach() {
    super.onDetach();
    mActionBarListener = null;
    mFragmentVisibilityListener = null;
}

Interface

    public interface OnFragmentInteractionListener {

void onActionBarListener(int title);

void onFragmentVisible(boolean isVisible);

Hope this helps anyone else!