Add SkinnableSprite class (#5137)

Add SkinnableSprite class

osu.Game.Rulesets.Osu/Objects/Drawables/Pieces/ApproachCircle.cs

@@ -4,7 +4,6 @@
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
-using osu.Framework.Graphics.Sprites;
 using osu.Framework.Graphics.Textures;
 using osu.Game.Skinning;
 
@@ -25,7 +24,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
         [BackgroundDependencyLoader]
         private void load(TextureStore textures)
         {
-            Child = new SkinnableDrawable("Play/osu/approachcircle", name => new Sprite { Texture = textures.Get(name) });
+            Child = new SkinnableSprite("Play/osu/approachcircle");
         }
     }
 }

osu.Game/Skinning/SkinnableDrawable.cs

@@ -15,6 +15,10 @@ namespace osu.Game.Skinning
         }
     }
 
+    /// <summary>
+    /// A drawable which can be skinned via an <see cref="ISkinSource"/>.
+    /// </summary>
+    /// <typeparam name="T">The type of drawable.</typeparam>
     public class SkinnableDrawable<T> : SkinReloadableDrawable
         where T : Drawable
     {
@@ -23,48 +27,63 @@ namespace osu.Game.Skinning
         /// </summary>
         protected Drawable Drawable { get; private set; }
 
-        private readonly Func<string, T> createDefault;
-
         private readonly string componentName;
 
         private readonly bool restrictSize;
 
         /// <summary>
-        ///
+        /// Create a new skinnable drawable.
         /// </summary>
         /// <param name="name">The namespace-complete resource name for this skinnable element.</param>
         /// <param name="defaultImplementation">A function to create the default skin implementation of this element.</param>
         /// <param name="allowFallback">A conditional to decide whether to allow fallback to the default implementation if a skinned element is not present.</param>
         /// <param name="restrictSize">Whether a user-skin drawable should be limited to the size of our parent.</param>
         public SkinnableDrawable(string name, Func<string, T> defaultImplementation, Func<ISkinSource, bool> allowFallback = null, bool restrictSize = true)
+            : this(name, allowFallback, restrictSize)
+        {
+            createDefault = defaultImplementation;
+        }
+
+        protected SkinnableDrawable(string name, Func<ISkinSource, bool> allowFallback = null, bool restrictSize = true)
             : base(allowFallback)
         {
             componentName = name;
-            createDefault = defaultImplementation;
             this.restrictSize = restrictSize;
 
             RelativeSizeAxes = Axes.Both;
         }
 
+        private readonly Func<string, T> createDefault;
+
+        protected virtual T CreateDefault(string name) => createDefault(name);
+
+        /// <summary>
+        /// Whether to apply size restrictions (specified via <see cref="restrictSize"/>) to the default implementation.
+        /// </summary>
+        protected virtual bool ApplySizeRestrictionsToDefault => false;
+
         protected override void SkinChanged(ISkinSource skin, bool allowFallback)
         {
             Drawable = skin.GetDrawableComponent(componentName);
 
+            bool isDefault = false;
+
+            if (Drawable == null && allowFallback)
+            {
+                Drawable = CreateDefault(componentName);
+                isDefault = true;
+            }
+
             if (Drawable != null)
             {
-                if (restrictSize)
+                if (restrictSize && (!isDefault || ApplySizeRestrictionsToDefault))
                 {
                     Drawable.RelativeSizeAxes = Axes.Both;
                     Drawable.Size = Vector2.One;
                     Drawable.Scale = Vector2.One;
                     Drawable.FillMode = FillMode.Fit;
                 }
-            }
-            else if (allowFallback)
-                Drawable = createDefault(componentName);
 
-            if (Drawable != null)
-            {
                 Drawable.Origin = Anchor.Centre;
                 Drawable.Anchor = Anchor.Centre;
 

osu.Game/Skinning/SkinnableSprite.cs

@@ -0,0 +1,28 @@
+// 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;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Graphics.Textures;
+
+namespace osu.Game.Skinning
+{
+    /// <summary>
+    /// A skinnable element which uses a stable sprite and can therefore share implementation logic.
+    /// </summary>
+    public class SkinnableSprite : SkinnableDrawable<Sprite>
+    {
+        protected override bool ApplySizeRestrictionsToDefault => true;
+
+        [Resolved]
+        private TextureStore textures { get; set; }
+
+        public SkinnableSprite(string name, Func<ISkinSource, bool> allowFallback = null, bool restrictSize = true)
+            : base(name, allowFallback, restrictSize)
+        {
+        }
+
+        protected override Sprite CreateDefault(string name) => new Sprite { Texture = textures.Get(name) };
+    }
+}