Merge fc90cfa604d37e1b063f7f5bffbb9f2d5a3cb015 into f8c419f9babb4991c581f4c11ca724936fb275eb

osu.Game/Graphics/Containers/BeatSyncedContainer.cs

@@ -0,0 +1,62 @@
+// 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.Allocation;
+using osu.Framework.Configuration;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Beatmaps;
+using osu.Game.Beatmaps.Timing;
+
+namespace osu.Game.Graphics.Containers
+{
+    public class BeatSyncedContainer : Container
+    {
+        /// <summary>
+        /// A new beat will not be sent if the time since the beat is larger than this tolerance.
+        /// </summary>
+        private const int seek_tolerance = 20;
+
+        private readonly Bindable<WorkingBeatmap> beatmap = new Bindable<WorkingBeatmap>();
+
+        private int lastBeat;
+        private ControlPoint lastControlPoint;
+
+        protected override void Update()
+        {
+            if (beatmap.Value?.Track == null)
+                return;
+
+            double currentTrackTime = beatmap.Value.Track.CurrentTime;
+            ControlPoint overridePoint;
+            ControlPoint controlPoint = beatmap.Value.Beatmap.TimingInfo.TimingPointAt(currentTrackTime, out overridePoint);
+
+            bool kiai = (overridePoint ?? controlPoint).KiaiMode;
+            int beat = controlPoint.BeatLength > 0 ? (int)((currentTrackTime - controlPoint.Time) / controlPoint.BeatLength) : 0;
+
+            // The beats before the start of the first control point are off by 1, this should do the trick
+            if (currentTrackTime < controlPoint.Time)
+                beat--;
+
+            if (controlPoint == lastControlPoint && beat == lastBeat)
+                return;
+
+            if ((currentTrackTime - controlPoint.Time) % controlPoint.BeatLength > seek_tolerance)
+                return;
+
+            OnNewBeat(beat, controlPoint.BeatLength, controlPoint.TimeSignature, kiai);
+
+            lastBeat = beat;
+            lastControlPoint = controlPoint;
+        }
+
+        protected virtual void OnNewBeat(int newBeat, double beatLength, TimeSignatures timeSignature, bool kiai)
+        {
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuGameBase game)
+        {
+            beatmap.BindTo(game.Beatmap);
+        }
+    }
+}

osu.Game/osu.Game.csproj

@@ -292,6 +292,7 @@
     <Compile Include="Graphics\UserInterface\RollingCounter.cs" />
     <Compile Include="Graphics\UserInterface\Volume\VolumeControlReceptor.cs" />
     <Compile Include="Graphics\Backgrounds\Background.cs" />
+    <Compile Include="Graphics\Containers\BeatSyncedContainer.cs" />
     <Compile Include="Graphics\Containers\ParallaxContainer.cs" />
     <Compile Include="Graphics\Cursor\MenuCursor.cs" />
     <Compile Include="Graphics\Processing\RatioAdjust.cs" />