RecyclerView onDrawOver view disappear after scroll

Question

I want to display a View (example TextView) over the RecyclerView after scroll to a position (example: 3) so I use

public class HeaderItemDecoration extends RecyclerView.ItemDecoration {

    @Override
    public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
        super.onDrawOver(c, parent, state);
        int topChildPosition = parent.getChildAdapterPosition(parent.getChildAt(0));

        if(topChildPosition == 3) {
            Log.i("TAG", "draw header");
            TextView textView = new TextView(parent.getContext());
            textView.setText("bbdasdasd");
            textView.setBackgroundColor(Color.RED);
            textView.layout(0, 0, 100, 100);
            drawText(c, textView);
        }
    }

    private void drawText(Canvas c, View header) {
        c.save();
        c.translate(0, 0);
        header.draw(c);
        c.restore();
    }
}

and

mRecyclerView.addItemDecoration(new HeaderItemDecoration());

I work but the problem is this TextView will gone if I continue scroll. How to make this View always visible after I draw it? Any help or suggestion would be great appreciated.

Answer 1

Just change the if condition:

if(topChildPosition == 3) {
    ...
}

to:

if(topChildPosition >= 3) {
    ...
}

So the view will remain visible if you continue to scroll down.

If you want it remain visible even if you scroll back to top, just add a member variable to remember if the view is already shown, if it's shown, keep drawing it.