FAB disappearing on RecyclerView with StaggeredGridLayout

[ffalcinelli]

I'm trying to implement hide/show events on scrolling a RecyclerView with a StaggeredGridLayout. Right now even if I don't invoke fab.attachToRecyclerView(recyclerView) it keeps disappearing when I scroll down. During the scrolling in the onScrolled callback the method fab.isShown() does always return true.

The layout is really trivial:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#e8e8e8"
        android:scrollbars="vertical" />

    <com.melnykov.fab.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="16dp"
        android:src="@drawable/ic_plus"
        app:fab_colorNormal="@color/accentLight"
        app:fab_colorPressed="@color/accent" />

</FrameLayout>

while in my fragment

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        final View view = inflater.inflate(R.layout.fragment_notes_list, container, false);
        recyclerView = (RecyclerView) view.findViewById(R.id.recycler);
        recyclerView.setLayoutManager(new StaggeredGridLayoutManager(howManyColumnsDisplayable(), StaggeredGridLayoutManager.VERTICAL));
        recyclerView.setAdapter(adapter);
        fab = (FloatingActionButton) view.findViewById(R.id.fab);

        recyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() {
            boolean scrollDown;

            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
                if (scrollDown) {
                    if (toolbarHandler.isToolbarShown())
                        toolbarHandler.hideToolbar();
                    if (fab.isShown()) {
                        Log.d(TAG, "Hiding FAB");
                        fab.hide(true);
                    }

                } else {
                    if (toolbarHandler.isToolbarHidden())
                        toolbarHandler.showToolbar();
                    if (!fab.isShown()) {
                        Log.d(TAG, "Showing FAB");
                        fab.show(true);
                    }
                }
            }

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                if (dy > 70) {
                    scrollDown = true;
                } else if (dy < -5) {
                    scrollDown = false;
                }
            }
        });
        return view;
    }

Am I missing something?

[JoniDS]

That's because dy is the amount of scroll and not the currentScroll position. You should keep a global variable: private currentScrollY=0;

and then update it:

@Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); currentScrollY+=dy; if (currentScrollY > 70) { scrollDown = true; } else if (currentScrollY < -5) { scrollDown = false; } }

[dushan135]

what is "toolbarHandler"???????????

[dosantosdp]

this is correct answer :

recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);

                if (dy >0) {
                    // Scroll Down
                    if (fab.isShown()) {
                        fab.hide();
                    }
                } else if (dy <0) {
                    // Scroll Up
                    if (!fab.isShown()) {
                        fab.show();
                    }
                }
            }
        });