osu/osu.Game/Storyboards/CommandTimeline.cs

// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE

using osu.Framework.Caching;
using osu.Framework.Graphics;
using System.Collections.Generic;
using System.Linq;

namespace osu.Game.Storyboards
{
    public class CommandTimeline<T> : CommandTimeline
    {
        private readonly List<Command> commands = new List<Command>();
        public IEnumerable<Command> Commands => commands.OrderBy(c => c.StartTime);
        public bool HasCommands => commands.Count > 0;

        private Cached<double> startTimeBacking;
        public double StartTime => startTimeBacking.IsValid ? startTimeBacking : (startTimeBacking.Value = HasCommands ? commands.Min(c => c.StartTime) : double.MinValue);

        private Cached<double> endTimeBacking;
        public double EndTime => endTimeBacking.IsValid ? endTimeBacking : (endTimeBacking.Value = HasCommands ? commands.Max(c => c.EndTime) : double.MaxValue);
        
        public T StartValue => HasCommands ? commands.OrderBy(c => c.StartTime).First().StartValue : default(T);
        public T EndValue => HasCommands ? commands.OrderByDescending(c => c.EndTime).First().EndValue : default(T);

        public void Add(Easing easing, double startTime, double endTime, T startValue, T endValue)
        {
            if (endTime < startTime)
                return;

            commands.Add(new Command { Easing = easing, StartTime = startTime, EndTime = endTime, StartValue = startValue, EndValue = endValue, });

            startTimeBacking.Invalidate();
            endTimeBacking.Invalidate();
        }

        public override string ToString()
            => $"{commands.Count} command(s)";

        public class Command
        {
            public Easing Easing;
            public double StartTime;
            public double EndTime;
            public T StartValue;
            public T EndValue;

            public double Duration => EndTime - StartTime;

            public override string ToString()
                => $"{StartTime} -> {EndTime}, {StartValue} -> {EndValue} {Easing}";
        }
    }

    public interface CommandTimeline
    {
        double StartTime { get; }
        double EndTime { get; }
        bool HasCommands { get; }
    }
}