protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.activity_demo);
_scrollView = FindViewById<ParallaxScrollView>(Resource.Id.scroll_view);
_factorText = FindViewById<TextView>(Resource.Id.factor_text);
_minus = FindViewById<Button>(Resource.Id.minus);
_minus.SetOnClickListener(this);
_plus = FindViewById<Button>(Resource.Id.plus);
_plus.SetOnClickListener(this);
}