Add StarDifficulty property and correct colouring of difficulty icons.

osu.Game/Beatmaps/Drawables/BeatmapPanel.cs

@@ -131,7 +131,7 @@ namespace osu.Game.Beatmaps.Drawables
                                         },
                                     }
                                 },
-                                new StarCounter { Count = beatmap.BaseDifficulty?.OverallDifficulty ?? 5, StarSize = 8 }
+                                new StarCounter { Count = beatmap.StarDifficulty, StarSize = 8 }
                             }
                         }
                     }

osu.Game/Beatmaps/Drawables/DifficultyIcon.cs

@@ -1,7 +1,10 @@
 //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 osu.Framework.Allocation;
 using osu.Framework.Graphics;
+using osu.Framework.Graphics.Colour;
 using osu.Framework.Graphics.Containers;
 using osu.Game.Database;
 using osu.Game.Graphics;
@@ -13,20 +16,76 @@ namespace osu.Game.Beatmaps.Drawables
 {
     class DifficultyIcon : Container
     {
+        private readonly BeatmapInfo beatmap;
+        private OsuColour palette;
+
         public DifficultyIcon(BeatmapInfo beatmap)
         {
+            this.beatmap = beatmap;
             const float size = 20;
             Size = new Vector2(size);
-            Children = new[]
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour palette)
+        {
+            this.palette = palette;
+
+            Children = new[]
             {
                 new TextAwesome
                 {
                     Anchor = Anchor.Centre,
-                    TextSize = size,
+                    TextSize = Size.X,
-                    Colour = new Color4(159, 198, 0, 255),
+                    Colour = getColour(beatmap),
+                    Icon = FontAwesome.fa_circle
+                },
+                new TextAwesome
+                {
+                    Anchor = Anchor.Centre,
+                    TextSize = Size.X,
+                    Colour = Color4.White,
                     Icon = Ruleset.GetRuleset(beatmap.Mode).Icon
                 }
-            };
+            };
+        }
+
+        enum DifficultyRating
+        {
+            Easy,
+            Normal,
+            Hard,
+            Insane,
+            Expert
+        }
+
+        private DifficultyRating getDifficultyRating(BeatmapInfo beatmap)
+        {
+            var rating = beatmap.StarDifficulty;
+
+            if (rating < 1.5) return DifficultyRating.Easy;
+            if (rating < 2.25) return DifficultyRating.Normal;
+            if (rating < 3.75) return DifficultyRating.Hard;
+            if (rating < 5.25) return DifficultyRating.Insane;
+            return DifficultyRating.Expert;
+        }
+
+        private Color4 getColour(BeatmapInfo beatmap)
+        {
+            switch (getDifficultyRating(beatmap))
+            {
+                case DifficultyRating.Easy:
+                    return palette.Green;
+                default:
+                case DifficultyRating.Normal:
+                    return palette.Yellow;
+                case DifficultyRating.Hard:
+                    return palette.Pink;
+                case DifficultyRating.Insane:
+                    return palette.Purple;
+                case DifficultyRating.Expert:
+                    return palette.Gray0;
+            }
         }
     }
 }

osu.Game/Database/BeatmapInfo.cs

@@ -73,6 +73,8 @@ namespace osu.Game.Database
         // Metadata
         public string Version { get; set; }
 
+        public float StarDifficulty => BaseDifficulty?.OverallDifficulty ?? 5; //todo: implement properly
+
         public bool Equals(BeatmapInfo other)
         {
             return ID == other?.ID;

osu.Game/Graphics/OsuColour.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using OpenTK.Graphics;
 using osu.Framework.Graphics.Colour;
 
@@ -17,11 +18,23 @@ namespace osu.Game.Graphics
 
         private static Color4 FromHex(string hex)
         {
-            return new Color4(
+            switch (hex.Length)
-                Convert.ToByte(hex.Substring(0, 2), 16),
+            {
-                Convert.ToByte(hex.Substring(2, 2), 16),
+                default:
-                Convert.ToByte(hex.Substring(4, 2), 16),
+                    throw new Exception(@"Invalid hex string length!");
-                255);
+                case 3:
+                    return new Color4(
+                        (byte)(Convert.ToByte(hex.Substring(0, 1), 16) * 17),
+                        (byte)(Convert.ToByte(hex.Substring(1, 1), 16) * 17),
+                        (byte)(Convert.ToByte(hex.Substring(2, 1), 16) * 17),
+                        255);
+                case 6:
+                    return new Color4(
+                        Convert.ToByte(hex.Substring(0, 2), 16),
+                        Convert.ToByte(hex.Substring(2, 2), 16),
+                        Convert.ToByte(hex.Substring(4, 2), 16),
+                        255);
+            }
         }
 
         // See https://github.com/ppy/osu-web/blob/master/resources/assets/less/colors.less
@@ -56,6 +69,23 @@ namespace osu.Game.Graphics
         public Color4 GreenDark = FromHex(@"668800");
         public Color4 GreenDarker = FromHex(@"445500");
 
+        public Color4 Gray0 = FromHex(@"000");
+        public Color4 Gray1 = FromHex(@"111");
+        public Color4 Gray2 = FromHex(@"222");
+        public Color4 Gray3 = FromHex(@"333");
+        public Color4 Gray4 = FromHex(@"444");
+        public Color4 Gray5 = FromHex(@"555");
+        public Color4 Gray6 = FromHex(@"666");
+        public Color4 Gray7 = FromHex(@"777");
+        public Color4 Gray8 = FromHex(@"888");
+        public Color4 Gray9 = FromHex(@"999");
+        public Color4 GrayA = FromHex(@"aaa");
+        public Color4 GrayB = FromHex(@"bbb");
+        public Color4 GrayC = FromHex(@"ccc");
+        public Color4 GrayD = FromHex(@"ddd");
+        public Color4 GrayE = FromHex(@"eee");
+        public Color4 GrayF = FromHex(@"fff");
+
         public Color4 Red = FromHex(@"fc4549");
     }
 }

osu.Game/Screens/Select/PlaySongSelect.cs

@@ -310,7 +310,7 @@ namespace osu.Game.Screens.Select
                 if (b.Metadata == null) b.Metadata = beatmapSet.Metadata;
             });
 
-            beatmapSet.Beatmaps = beatmapSet.Beatmaps.OrderBy(b => b.BaseDifficulty.OverallDifficulty).ToList();
+            beatmapSet.Beatmaps = beatmapSet.Beatmaps.OrderBy(b => b.StarDifficulty).ToList();
 
             var beatmap = new WorkingBeatmap(beatmapSet.Beatmaps.FirstOrDefault(), beatmapSet, database);