Move beatmap play button nearer its only remaining usage

osu.Game/Overlays/BeatmapSet/Buttons/PlayButton.cs

@@ -0,0 +1,175 @@
+// 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 osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Input.Events;
+using osu.Game.Audio;
+using osu.Game.Graphics;
+using osu.Game.Graphics.UserInterface;
+using osu.Game.Online.API.Requests.Responses;
+using osuTK;
+using osuTK.Graphics;
+
+namespace osu.Game.Overlays.BeatmapSet.Buttons
+{
+    public class PlayButton : Container
+    {
+        public IBindable<bool> Playing => playing;
+
+        private readonly BindableBool playing = new BindableBool();
+
+        public PreviewTrack Preview { get; private set; }
+
+        private APIBeatmapSet beatmapSet;
+
+        public APIBeatmapSet BeatmapSet
+        {
+            get => beatmapSet;
+            set
+            {
+                if (value == beatmapSet) return;
+
+                beatmapSet = value;
+
+                Preview?.Stop();
+                Preview?.Expire();
+                Preview = null;
+
+                playing.Value = false;
+            }
+        }
+
+        private Color4 hoverColour;
+        private readonly SpriteIcon icon;
+        private readonly LoadingSpinner loadingSpinner;
+
+        private const float transition_duration = 500;
+
+        private bool loading
+        {
+            set
+            {
+                if (value)
+                {
+                    icon.FadeTo(0.5f, transition_duration, Easing.OutQuint);
+                    loadingSpinner.Show();
+                }
+                else
+                {
+                    icon.FadeTo(1, transition_duration, Easing.OutQuint);
+                    loadingSpinner.Hide();
+                }
+            }
+        }
+
+        public PlayButton(APIBeatmapSet setInfo = null)
+        {
+            BeatmapSet = setInfo;
+            AddRange(new Drawable[]
+            {
+                icon = new SpriteIcon
+                {
+                    Anchor = Anchor.Centre,
+                    Origin = Anchor.Centre,
+                    FillMode = FillMode.Fit,
+                    RelativeSizeAxes = Axes.Both,
+                    Icon = FontAwesome.Solid.Play,
+                },
+                loadingSpinner = new LoadingSpinner
+                {
+                    Size = new Vector2(15),
+                },
+            });
+
+            playing.ValueChanged += playingStateChanged;
+        }
+
+        [Resolved]
+        private PreviewTrackManager previewTrackManager { get; set; }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour colour)
+        {
+            hoverColour = colour.Yellow;
+        }
+
+        protected override bool OnClick(ClickEvent e)
+        {
+            playing.Toggle();
+            return true;
+        }
+
+        protected override bool OnHover(HoverEvent e)
+        {
+            icon.FadeColour(hoverColour, 120, Easing.InOutQuint);
+            return base.OnHover(e);
+        }
+
+        protected override void OnHoverLost(HoverLostEvent e)
+        {
+            if (!playing.Value)
+                icon.FadeColour(Color4.White, 120, Easing.InOutQuint);
+            base.OnHoverLost(e);
+        }
+
+        private void playingStateChanged(ValueChangedEvent<bool> e)
+        {
+            icon.Icon = e.NewValue ? FontAwesome.Solid.Stop : FontAwesome.Solid.Play;
+            icon.FadeColour(e.NewValue || IsHovered ? hoverColour : Color4.White, 120, Easing.InOutQuint);
+
+            if (e.NewValue)
+            {
+                if (BeatmapSet == null)
+                {
+                    playing.Value = false;
+                    return;
+                }
+
+                if (Preview != null)
+                {
+                    attemptStart();
+                    return;
+                }
+
+                loading = true;
+
+                LoadComponentAsync(Preview = previewTrackManager.Get(beatmapSet), preview =>
+                {
+                    // Make sure that we schedule to after the next audio frame to fix crashes in single-threaded execution.
+                    // See: https://github.com/ppy/osu-framework/issues/4692
+                    Schedule(() =>
+                    {
+                        // beatmapset may have changed.
+                        if (Preview != preview)
+                            return;
+
+                        AddInternal(preview);
+                        loading = false;
+                        // make sure that the update of value of Playing (and the ensuing value change callbacks)
+                        // are marshaled back to the update thread.
+                        preview.Stopped += () => Schedule(() => playing.Value = false);
+
+                        // user may have changed their mind.
+                        if (playing.Value)
+                            attemptStart();
+                    });
+                });
+            }
+            else
+            {
+                Preview?.Stop();
+                loading = false;
+            }
+        }
+
+        private void attemptStart()
+        {
+            if (Preview?.Start() != true)
+                playing.Value = false;
+        }
+    }
+}