Add HitObject colours back in the mix.

osu.Desktop.VisualTests/Tests/TestCasePlayer.cs

@@ -6,6 +6,7 @@ using osu.Framework.GameModes.Testing;
 using osu.Framework.MathUtils;
 using osu.Framework.Timing;
 using osu.Game.Beatmaps;
+using osu.Game.Beatmaps.Formats;
 using osu.Game.Beatmaps.Objects;
 using osu.Game.Beatmaps.Objects.Osu;
 using osu.Game.GameModes.Play;
@@ -38,20 +39,27 @@ namespace osu.Desktop.VisualTests.Tests
                 objects.Add(new Circle()
                 {
                     StartTime = time,
-                    Position = new Vector2(RNG.Next(100, 400), RNG.Next(100, 200))
+                    Position = new Vector2(RNG.Next(0, 512), RNG.Next(0, 384)),
+                    NewCombo = (i + 1) % 4 == 0
                 });
 
                 time += 500;
             }
 
+            var decoder = new ConstructableBeatmapDecoder();
+
+            Beatmap b = new Beatmap
+            {
+                HitObjects = objects
+            };
+
+            decoder.Process(b);
+
             Add(new Player
             {
                 Beatmap = new WorkingBeatmap
                 {
-                    Beatmap = new Beatmap
-                    {
-                        HitObjects = objects
-                    }
+                    Beatmap = b
                 }
             });
         }

osu.Game/Beatmaps/Formats/BeatmapDecoder.cs

@@ -1,13 +1,15 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using osu.Game.Beatmaps.Objects;
+using OpenTK.Graphics;
 
 namespace osu.Game.Beatmaps.Formats
 {
     public abstract class BeatmapDecoder
     {
         private static Dictionary<string, Type> decoders { get; } = new Dictionary<string, Type>();
-    
+
         public static BeatmapDecoder GetDecoder(TextReader stream)
         {
             var line = stream.ReadLine().Trim();
@@ -20,7 +22,39 @@ namespace osu.Game.Beatmaps.Formats
         {
             decoders[magic] = typeof(T);
         }
-    
-        public abstract Beatmap Decode(TextReader stream);
+
+        public virtual Beatmap Decode(TextReader stream)
+        {
+            Beatmap b = ParseFile(stream);
+            Process(b);
+            return b;
+        }
+
+        public virtual Beatmap Process(Beatmap beatmap)
+        {
+            ApplyColours(beatmap);
+
+            return beatmap;
+        }
+
+        protected abstract Beatmap ParseFile(TextReader stream);
+
+        public virtual void ApplyColours(Beatmap b)
+        {
+            List<Color4> colours = b.ComboColors ?? new List<Color4>() {
+                new Color4(17, 136, 170, 255),
+                new Color4(102,136,0, 255),
+                new Color4(204,102,0, 255),
+                new Color4(121,9,13, 255),
+            };
+
+            int i = 0;
+
+            foreach (HitObject h in b.HitObjects)
+            {
+                h.Colour = colours[i];
+                if (h.NewCombo) i = (i + 1) % colours.Count;
+            }
+        }
     }
 }

osu.Game/Beatmaps/Formats/ConstructableBeatmapDecoder.cs

@@ -0,0 +1,20 @@
+//Copyright (c) 2007-2016 ppy Pty Ltd <contact@ppy.sh>.
+//Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace osu.Game.Beatmaps.Formats
+{
+    public class ConstructableBeatmapDecoder : BeatmapDecoder
+    {
+        protected override Beatmap ParseFile(TextReader stream)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

osu.Game/Beatmaps/Formats/OsuLegacyDecoder.cs

@@ -207,7 +207,7 @@ namespace osu.Game.Beatmaps.Formats
             });
         }
 
-        public override Beatmap Decode(TextReader stream)
+        protected override Beatmap ParseFile(TextReader stream)
         {
             var beatmap = new Beatmap
             {

osu.Game/Beatmaps/Objects/HitObject.cs

@@ -4,6 +4,7 @@
 using osu.Game.Beatmaps.Objects.Osu;
 using osu.Game.Beatmaps.Samples;
 using osu.Game.GameModes.Play;
+using OpenTK.Graphics;
 
 namespace osu.Game.Beatmaps.Objects
 {
@@ -15,6 +16,10 @@ namespace osu.Game.Beatmaps.Objects
         public double StartTime;
         public virtual double EndTime => StartTime;
 
+        public bool NewCombo { get; set; }
+
+        public Color4 Colour = new Color4(17, 136, 170, 255);
+
         public double Duration => EndTime - StartTime;
 
         public HitSampleInfo Sample;

osu.Game/Beatmaps/Objects/Osu/Circle.cs

@@ -7,6 +7,5 @@ namespace osu.Game.Beatmaps.Objects.Osu
 {
     public class Circle : OsuBaseHit
     {
-        public Color4 Colour = new Color4(17, 136, 170, 255);
     }
 }

osu.Game/Beatmaps/Objects/Osu/OsuBaseHit.cs

@@ -10,7 +10,6 @@ namespace osu.Game.Beatmaps.Objects.Osu
     public abstract class OsuBaseHit : HitObject
     {
         public Vector2 Position { get; set; }
-        public bool NewCombo { get; set; }
 
         [Flags]
         private enum HitObjectType

osu.Game/osu.Game.csproj

@@ -64,6 +64,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Beatmaps\Beatmap.cs" />
+    <Compile Include="Beatmaps\Formats\ConstructableBeatmapDecoder.cs" />
     <Compile Include="Beatmaps\WorkingBeatmap.cs" />
     <Compile Include="Beatmaps\Drawable\BeatmapSetHeader.cs" />
     <Compile Include="Beatmaps\Drawable\DifficultyIcon.cs" />