Code/SboxSuperuser/Core/Menu/Notices.cs
A small generic helper that holds short-lived pop-up notices for a menu. Keeps the newest 4 entries, drops them after a 5 second lifetime, and returns the remaining ones with an opacity value that fades over the last second.
namespace SboxSuperuser.Core.Menu;
/// <summary>
/// Short-lived pop-up notices, newest last. Each shows for a few seconds and fades out over its last second;
/// only the newest few are kept so a burst of results cannot fill the screen.
/// </summary>
internal sealed class Notices<T>
{
internal static readonly TimeSpan Lifetime = TimeSpan.FromSeconds( 5 );
private static readonly TimeSpan FadeTime = TimeSpan.FromSeconds( 1 );
internal const int MaximumShown = 4;
private readonly List<(T Value, DateTimeOffset Shown)> _items = new();
internal void Add( T value, DateTimeOffset now )
{
_items.Add( (value, now) );
if ( _items.Count > MaximumShown ) _items.RemoveAt( 0 );
}
/// <summary>Drops expired notices and returns the rest with their opacity (1 = fully visible).</summary>
internal IReadOnlyList<(T Value, float Opacity)> Visible( DateTimeOffset now )
{
_items.RemoveAll( item => now - item.Shown >= Lifetime );
return _items.Select( item =>
{
var left = Lifetime - (now - item.Shown);
var opacity = left >= FadeTime ? 1f : (float)(left / FadeTime);
return (item.Value, opacity);
} ).ToArray();
}
}