Implement beatmap card difficulty list

osu.Game/Beatmaps/Drawables/Cards/BeatmapCardDifficultyList.cs

@@ -0,0 +1,103 @@
+// 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.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Containers;
+using osu.Game.Online.Chat;
+using osu.Game.Rulesets;
+using osuTK;
+
+namespace osu.Game.Beatmaps.Drawables.Cards
+{
+    public class BeatmapCardDifficultyList : CompositeDrawable
+    {
+        public BeatmapCardDifficultyList(IBeatmapSetInfo beatmapSetInfo)
+        {
+            RelativeSizeAxes = Axes.X;
+            AutoSizeAxes = Axes.Y;
+
+            FillFlowContainer flow;
+
+            InternalChild = flow = new FillFlowContainer
+            {
+                RelativeSizeAxes = Axes.X,
+                AutoSizeAxes = Axes.Y,
+                Direction = FillDirection.Vertical,
+                Spacing = new Vector2(0, 3)
+            };
+
+            bool firstGroup = true;
+
+            foreach (var group in beatmapSetInfo.Beatmaps.GroupBy(beatmap => beatmap.Ruleset.OnlineID).OrderBy(group => group.Key))
+            {
+                if (!firstGroup)
+                {
+                    flow.Add(Empty().With(s =>
+                    {
+                        s.RelativeSizeAxes = Axes.X;
+                        s.Height = 4;
+                    }));
+                }
+
+                foreach (var difficulty in group.OrderBy(b => b.StarRating))
+                    flow.Add(new BeatmapCardDifficultyRow(difficulty));
+
+                firstGroup = false;
+            }
+        }
+
+        private class BeatmapCardDifficultyRow : CompositeDrawable
+        {
+            private readonly IBeatmapInfo beatmapInfo;
+
+            public BeatmapCardDifficultyRow(IBeatmapInfo beatmapInfo)
+            {
+                this.beatmapInfo = beatmapInfo;
+            }
+
+            [BackgroundDependencyLoader]
+            private void load(RulesetStore rulesets)
+            {
+                RelativeSizeAxes = Axes.X;
+                AutoSizeAxes = Axes.Y;
+
+                InternalChild = new FillFlowContainer
+                {
+                    RelativeSizeAxes = Axes.X,
+                    AutoSizeAxes = Axes.Y,
+                    Direction = FillDirection.Horizontal,
+                    Spacing = new Vector2(4, 0),
+                    Children = new[]
+                    {
+                        (rulesets.GetRuleset(beatmapInfo.Ruleset.OnlineID)?.CreateInstance().CreateIcon() ?? new SpriteIcon { Icon = FontAwesome.Regular.QuestionCircle }).With(icon =>
+                        {
+                            icon.Anchor = icon.Origin = Anchor.CentreLeft;
+                            icon.Size = new Vector2(16);
+                        }),
+                        new StarRatingDisplay(new StarDifficulty(beatmapInfo.StarRating, 0), StarRatingDisplaySize.Small)
+                        {
+                            Anchor = Anchor.CentreLeft,
+                            Origin = Anchor.CentreLeft
+                        },
+                        new LinkFlowContainer(s =>
+                        {
+                            s.Font = OsuFont.Default.With(size: 14, weight: FontWeight.SemiBold);
+                        }).With(d =>
+                        {
+                            d.AutoSizeAxes = Axes.Both;
+                            d.Anchor = Anchor.CentreLeft;
+                            d.Origin = Anchor.CentreLeft;
+                            d.Padding = new MarginPadding { Bottom = 2 };
+                            d.AddLink(beatmapInfo.DifficultyName, LinkAction.OpenBeatmap, beatmapInfo.OnlineID.ToString());
+                        })
+                    }
+                };
+            }
+        }
+    }
+}