osu-lazer/osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSliderTail.cs

// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

using System.Diagnostics;
using osu.Framework.Allocation;
using osu.Framework.Bindables;
using osu.Framework.Graphics;
using osu.Framework.Graphics.Containers;
using osu.Game.Rulesets.Objects.Drawables;
using osu.Game.Skinning;
using osuTK;

namespace osu.Game.Rulesets.Osu.Objects.Drawables
{
    public class DrawableSliderTail : DrawableOsuHitObject, IRequireTracking, ITrackSnaking
    {
        private readonly SliderTailCircle tailCircle;

        /// <summary>
        /// The judgement text is provided by the <see cref="DrawableSlider"/>.
        /// </summary>
        public override bool DisplayResult => false;

        public bool Tracking { get; set; }

        private readonly IBindable<float> scaleBindable = new BindableFloat();

        private readonly SkinnableDrawable circlePiece;

        private readonly Container scaleContainer;

        public DrawableSliderTail(Slider slider, SliderTailCircle tailCircle)
            : base(tailCircle)
        {
            this.tailCircle = tailCircle;
            Origin = Anchor.Centre;

            Size = new Vector2(OsuHitObject.OBJECT_RADIUS * 2);

            InternalChildren = new Drawable[]
            {
                scaleContainer = new Container
                {
                    RelativeSizeAxes = Axes.Both,
                    Origin = Anchor.Centre,
                    Anchor = Anchor.Centre,
                    Children = new Drawable[]
                    {
                        // no default for this; only visible in legacy skins.
                        circlePiece = new SkinnableDrawable(new OsuSkinComponent(OsuSkinComponents.SliderTailHitCircle), _ => Empty())
                    }
                },
            };
        }

        [BackgroundDependencyLoader]
        private void load()
        {
            scaleBindable.BindValueChanged(scale => scaleContainer.Scale = new Vector2(scale.NewValue), true);
            scaleBindable.BindTo(HitObject.ScaleBindable);
        }

        protected override void UpdateInitialTransforms()
        {
            base.UpdateInitialTransforms();

            circlePiece.FadeInFromZero(HitObject.TimeFadeIn);
        }

        protected override void UpdateStateTransforms(ArmedState state)
        {
            base.UpdateStateTransforms(state);

            Debug.Assert(HitObject.HitWindows != null);

            switch (state)
            {
                case ArmedState.Idle:
                    this.Delay(HitObject.TimePreempt).FadeOut(500);

                    Expire(true);
                    break;

                case ArmedState.Miss:
                    this.FadeOut(100);
                    break;

                case ArmedState.Hit:
                    // todo: temporary / arbitrary
                    this.Delay(800).FadeOut();
                    break;
            }
        }

        protected override void CheckForResult(bool userTriggered, double timeOffset)
        {
            if (!userTriggered && timeOffset >= 0)
                ApplyResult(r => r.Type = Tracking ? r.Judgement.MaxResult : r.Judgement.MinResult);
        }

        public void UpdateSnakingPosition(Vector2 start, Vector2 end) =>
            Position = tailCircle.RepeatIndex % 2 == 0 ? end : start;
    }
}