void Control_Scroll(object sender, AbsListView.ScrollEventArgs e)
{
int y = (int)(-e.View.GetChildAt(0).GetY() / 2);
if (y == lastY)
{
return;
}
if (e.FirstVisibleItem == 0 && y <= 255 && y >= 0)
{
CustomNavigationPage.SetBarBackgroundColor(Color.FromRgba(255, 80, 80, lastY = y));
}
else if (e.FirstVisibleItem != 0 && Math.Abs(lastY - 1) > double.Epsilon)
{
CustomNavigationPage.SetBarBackgroundColor(Color.FromRgba(255, 80, 80, lastY = 255));
}
}