Show view when toolbar collapses

Question

I have an activity with a CoordinatorLayout, AppBarLayout, CollapsingToolbarLayout and Toolbar. So, basically, a view tha

Answer 1

Taking a look at the CollapsingToolbarLayout source, the content scrim animations are triggered via an OnOffsetChangedListener on the AppBarLayout. So you could add another one to trigger alpha animations on your text view:

mListener = new AppBarLayout.OnOffsetChangedListener() {
    @Override
    public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
        if(collapsingToolbar.getHeight() + verticalOffset < 2 * ViewCompat.getMinimumHeight(collapsingToolbar)) {
            hello.animate().alpha(1).setDuration(600);
        } else {
            hello.animate().alpha(0).setDuration(600);
        }
    }
};

appBar.addOnOffsetChangedListener(mListener);