Hide FAB in NestedScrollView when scrolling

Question

I am having a nestedscrollview with content like some linearlayouts and textviews. I am using a floatingactionbutton library for some reasons, as well. So I can\'t use any behav

Answer 1

Create FabScrollBehavior class

public class FabScrollBehavior extends CoordinatorLayout.Behavior {
    private int toolbarHeight;

    public FabScrollBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.toolbarHeight = AppUtil.getToolbarHeight(context);
    }

    @Override
    public boolean layoutDependsOn(CoordinatorLayout parent, FloatingActionButton fab, View dependency) {
        return dependency instanceof AppBarLayout;
    }

    @Override
    public boolean onDependentViewChanged(CoordinatorLayout parent, FloatingActionButton fab, View dependency) {
        if (dependency instanceof AppBarLayout) {
            CoordinatorLayout.LayoutParams lp = (CoordinatorLayout.LayoutParams) fab.getLayoutParams();
            int fabBottomMargin = lp.bottomMargin;
            int distanceToScroll = fab.getHeight() + fabBottomMargin;
            float ratio = (float)dependency.getY()/(float)toolbarHeight;
            fab.setTranslationY(-distanceToScroll * ratio);
        }
        return true;
    }
}

Where AppUtil.getToolbarHeight(context) is -

public static int getToolbarHeight(Context context) {
        final TypedArray styledAttributes = context.getTheme().obtainStyledAttributes(
                new int[]{R.attr.actionBarSize});
        int toolbarHeight = (int) styledAttributes.getDimension(0, 0);
        styledAttributes.recycle();

        return toolbarHeight;
    }

then in your layout add to FloatingActionButton layout_behavior:

The whole layout looks like

Implemented from https://mzgreen.github.io/2015/02/15/How-to-hideshow-Toolbar-when-list-is-scroling(part1)/