Limit comment sprite height

osu.Game/Overlays/Comments/CommentMarkdownContainer.cs

@@ -1,9 +1,17 @@
 // 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.
 
+#nullable disable
+
 using Markdig.Syntax;
+using Markdig.Syntax.Inlines;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Containers.Markdown;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Graphics.Textures;
 using osu.Game.Graphics.Containers.Markdown;
+using osuTK;
 
 namespace osu.Game.Overlays.Comments
 {
@@ -16,6 +24,8 @@ namespace osu.Game.Overlays.Comments
 
         protected override MarkdownHeading CreateHeading(HeadingBlock headingBlock) => new CommentMarkdownHeading(headingBlock);
 
+        public override MarkdownTextFlowContainer CreateTextFlow() => new CommentMarkdownTextFlowContainer();
+
         private partial class CommentMarkdownHeading : OsuMarkdownHeading
         {
             public CommentMarkdownHeading(HeadingBlock headingBlock)
@@ -40,5 +50,64 @@ namespace osu.Game.Overlays.Comments
                 }
             }
         }
+
+        private partial class CommentMarkdownTextFlowContainer : MarkdownTextFlowContainer
+        {
+            protected override void AddImage(LinkInline linkInline) => AddDrawable(new CommentMarkdownImage(linkInline.Url));
+
+            private partial class CommentMarkdownImage : MarkdownImage
+            {
+                public CommentMarkdownImage(string url)
+                    : base(url)
+                {
+                }
+
+                private DelayedLoadWrapper wrapper;
+
+                protected override Drawable CreateContent(string url) => wrapper = new DelayedLoadWrapper(CreateImageContainer(url));
+
+                protected override ImageContainer CreateImageContainer(string url)
+                {
+                    var container = new CommentImageContainer(url);
+                    container.OnLoadComplete += d =>
+                    {
+                        // The size of DelayedLoadWrapper depends on AutoSizeAxes of it's content.
+                        // But since it's set to None, we need to specify the size here manually.
+                        wrapper.Size = container.Size;
+                        d.FadeInFromZero(300, Easing.OutQuint);
+                    };
+                    return container;
+                }
+
+                private partial class CommentImageContainer : ImageContainer
+                {
+                    // https://github.com/ppy/osu-web/blob/3bd0f406dc78d60b356d955cd4201f8c3e1cca09/resources/css/bem/osu-md.less#L36
+                    // Web version defines max height in em units (6 em), which assuming default pixel size as 14 results in 84 px,
+                    // which also seems to match my observations upon expecting the web element.
+                    private const float max_height = 84f;
+
+                    public CommentImageContainer(string url)
+                        : base(url)
+                    {
+                        AutoSizeAxes = Axes.None;
+                    }
+
+                    protected override Sprite CreateImageSprite() => new Sprite
+                    {
+                        RelativeSizeAxes = Axes.Both
+                    };
+
+                    protected override Texture GetImageTexture(TextureStore textures, string url)
+                    {
+                        Texture t = base.GetImageTexture(textures, url);
+
+                        if (t != null)
+                            Size = t.Height > 96 ? new Vector2(max_height / t.Height * t.Width, max_height) : t.Size;
+
+                        return t;
+                    }
+                }
+            }
+        }
     }
 }