Add timeline beat display

osu.Game.Tests/Visual/Editor/TestSceneTimelineBeatLineDisplay.cs

@@ -0,0 +1,32 @@
+// 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 NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Game.Screens.Edit.Compose.Components;
+using osu.Game.Screens.Edit.Compose.Components.Timeline;
+using osuTK;
+
+namespace osu.Game.Tests.Visual.Editor
+{
+    [TestFixture]
+    public class TestSceneTimelineBeatLineDisplay : TimelineTestScene
+    {
+        public override Drawable CreateTestComponent() => new TimelineBeatLineDisplay();
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            BeatDivisor.Value = 4;
+
+            Add(new BeatDivisorControl(BeatDivisor)
+            {
+                Anchor = Anchor.TopRight,
+                Origin = Anchor.TopRight,
+                Margin = new MarginPadding(30),
+                Size = new Vector2(90)
+            });
+        }
+    }
+}

osu.Game/Screens/Edit/Components/Timelines/Summary/Visualisations/PointVisualisation.cs

@@ -12,7 +12,7 @@ namespace osu.Game.Screens.Edit.Components.Timelines.Summary.Visualisations
     /// </summary>
     public class PointVisualisation : Box
     {
-        protected PointVisualisation(double startTime)
+        public PointVisualisation(double startTime)
         {
             Origin = Anchor.TopCentre;
 

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineBeatLineDisplay.cs

@@ -0,0 +1,90 @@
+// 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.Linq;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Game.Beatmaps;
+using osu.Game.Graphics;
+using osu.Game.Screens.Edit.Components.Timelines.Summary.Parts;
+using osu.Game.Screens.Edit.Components.Timelines.Summary.Visualisations;
+
+namespace osu.Game.Screens.Edit.Compose.Components.Timeline
+{
+    public class TimelineBeatLineDisplay : TimelinePart
+    {
+        [Resolved]
+        private EditorBeatmap beatmap { get; set; }
+
+        [Resolved]
+        private Bindable<WorkingBeatmap> working { get; set; }
+
+        [Resolved]
+        private BindableBeatDivisor beatDivisor { get; set; }
+
+        [Resolved]
+        private OsuColour colours { get; set; }
+
+        public TimelineBeatLineDisplay()
+        {
+            RelativeSizeAxes = Axes.Both;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            beatDivisor.BindValueChanged(_ => createLines(), true);
+        }
+
+        private void createLines()
+        {
+            Clear();
+
+            for (var i = 0; i < beatmap.ControlPointInfo.TimingPoints.Count; i++)
+            {
+                var point = beatmap.ControlPointInfo.TimingPoints[i];
+                var until = beatmap.ControlPointInfo.TimingPoints.Count < i + 1 ? beatmap.ControlPointInfo.TimingPoints[i + 1].Time : working.Value.Track.Length;
+
+                int beat = 0;
+
+                for (double t = point.Time; t < until; t += point.BeatLength / beatDivisor.Value)
+                {
+                    var indexInBeat = beat % beatDivisor.Value;
+
+                    if (indexInBeat == 0)
+                    {
+                        Add(new PointVisualisation(t)
+                        {
+                            Colour = BindableBeatDivisor.GetColourFor(1, colours),
+                            Anchor = Anchor.BottomLeft,
+                            Origin = Anchor.BottomLeft,
+                        });
+                    }
+                    else
+                    {
+                        var divisor = BindableBeatDivisor.GetDivisorForBeatIndex(beat, beatDivisor.Value);
+                        var colour = BindableBeatDivisor.GetColourFor(divisor, colours);
+                        var height = 0.1f - (float)divisor / BindableBeatDivisor.VALID_DIVISORS.Last() * 0.08f;
+
+                        Add(new PointVisualisation(t)
+                        {
+                            Colour = colour,
+                            Height = height,
+                        });
+
+                        Add(new PointVisualisation(t)
+                        {
+                            Colour = colour,
+                            Anchor = Anchor.BottomLeft,
+                            Origin = Anchor.BottomLeft,
+                            Height = height,
+                        });
+                    }
+
+                    beat++;
+                }
+            }
+        }
+    }
+}

osu.Game/Screens/Edit/EditorScreenWithTimeline.cs

@@ -102,7 +102,11 @@ namespace osu.Game.Screens.Edit
                 LoadComponentAsync(new TimelineArea
                 {
                     RelativeSizeAxes = Axes.Both,
-                    Child = CreateTimelineContent()
+                    Children = new[]
+                    {
+                        new TimelineBeatLineDisplay(),
+                        CreateTimelineContent(),
+                    }
                 }, timelineContainer.Add);
             });
         }