Fix explicit definition of nested styles, resolve parent style if the style for the variant is not present in the stylesheet.

TestGame/Resources/default.style.toml

@@ -1,12 +1,9 @@
 [Button]
 BackgroundColor = "#0f62fe"
+CornerRadius = 16.0
 TextColor = "#ffffff"
 Padding = 16.0
 
-# Creates an empty rule for Button.Normal.
-# This will inherit style from Button, this is a temporary workaround.
-[Button.Normal]
-
 [Button.Hovered]
 BackgroundColor = "#0353e9"
 

Voile/Source/UI/Style.cs

@@ -11,7 +11,7 @@ namespace Voile.UI;
 /// </summary>
 public class Style
 {
-    public enum AnimationType
+    public enum TransitionType
     {
         Linear,
         EaseIn,
@@ -20,7 +20,7 @@ public class Style
     }
 
     public float TransitionDuration = 0f;
-    public AnimationType TransitionType = AnimationType.Linear;
+    public TransitionType Transition = TransitionType.Linear;
 
     public Style() { }
 
@@ -35,17 +35,39 @@ public class Style
     /// Merges this <see cref="Style"/> with a different one.<br />
     /// Properties that are not set for this <see cref="Style"/> will be inherited from <paramref name="overrideStyle"/>.
     /// </summary>
-    /// <param name="overrideStyle"></param>
+    /// <param name="other"></param>
     /// <returns>A merged <see cref="Style"/>.</returns>
-    public Style Merge(Style overrideStyle)
+    public Style Merge(Style other)
     {
         return new Style
         {
-            BackgroundColor = overrideStyle.BackgroundColor != default ? overrideStyle.BackgroundColor : BackgroundColor,
+            Padding =
-            TextColor = overrideStyle.TextColor != default ? overrideStyle.TextColor : TextColor,
+                other.Padding ?? Padding,
-            Padding = overrideStyle.Padding != default ? overrideStyle.Padding : Padding,
+
-            BorderSize = overrideStyle.BorderSize != default ? overrideStyle.BorderSize : BorderSize,
+            BackgroundColor =
-            BorderColor = overrideStyle.BorderColor != default ? overrideStyle.BorderColor : BorderColor,
+                other.BackgroundColor ?? BackgroundColor,
+
+            BorderSize =
+                other.BorderSize ?? BorderSize,
+
+            BorderColor =
+                other.BorderColor ?? BorderColor,
+
+            TextColor =
+                other.TextColor ?? TextColor,
+
+            CornerRadius =
+                other.CornerRadius != default
+                    ? other.CornerRadius
+                    : CornerRadius,
+
+            TransitionDuration =
+                other.TransitionDuration != default
+                    ? other.TransitionDuration
+                    : TransitionDuration,
+
+            Transition =
+                other.Transition
         };
     }
 }
@@ -88,12 +110,12 @@ public class StyleSheetLoader : ResourceLoader<StyleSheet>
     {
         var style = new Style();
 
-        string easingName = reader.GetString("TransitionType", "Linear");
+        string transitionName = reader.GetString("TransitionType", "Linear");
 
-        if (!Enum.TryParse<Style.AnimationType>(easingName, true, out var easing))
+        if (!Enum.TryParse<Style.TransitionType>(transitionName, true, out var transition))
-            easing = Style.AnimationType.Linear;
+            throw new ArgumentException($"\"{transitionName}\" is not a valid TransitionType.");
 
-        style.TransitionType = easing;
+        style.Transition = transition;
 
 
         if (reader.HasKey("BackgroundColor"))
@@ -147,9 +169,13 @@ public class StyleSheet : Resource
 
     public void Add(string key, Style style) => _styles.Add(key, style);
 
-    public bool TryGet(string styleName, [NotNullWhen(true)] out Style? style)
+    public bool TryGet(
+        string styleName,
+        [NotNullWhen(true)] out Style? style)
     {
-        return _styles.TryGetValue(styleName, out style);
+        style = Resolve(styleName);
+
+        return style != null;
     }
 
     public static StyleSheet Default => new(new Dictionary<string, Style>()
@@ -226,5 +252,29 @@ public class StyleSheet : Resource
         }},
     });
 
+    private Style? Resolve(string fullKey)
+    {
+        var parts = fullKey.Split('.');
+
+        Style? merged = null;
+
+        for (int i = 1; i <= parts.Length; i++)
+        {
+            var subKey = string.Join('.',
+                parts.Take(i));
+
+            if (_styles.TryGetValue(
+                subKey,
+                out var style))
+            {
+                merged ??= new Style();
+
+                merged = merged.Merge(style);
+            }
+        }
+
+        return merged;
+    }
+
     private Dictionary<string, Style> _styles = new();
 }

Voile/Source/UI/StyleAnimator.cs

@@ -13,14 +13,14 @@ public class StyleAnimator
         _elapsed = 0f;
     }
 
-    public static float Ease(float t, Style.AnimationType type)
+    public static float Ease(float t, Style.TransitionType type)
     {
         return type switch
         {
-            Style.AnimationType.Linear => t,
+            Style.TransitionType.Linear => t,
-            Style.AnimationType.EaseIn => t * t,
+            Style.TransitionType.EaseIn => t * t,
-            Style.AnimationType.EaseOut => t * (2 - t),
+            Style.TransitionType.EaseOut => t * (2 - t),
-            Style.AnimationType.EaseInOut => t < 0.5f
+            Style.TransitionType.EaseInOut => t < 0.5f
                 ? 2 * t * t
                 : -1 + (4 - 2 * t) * t,
             _ => t
@@ -31,7 +31,7 @@ public class StyleAnimator
     {
         _elapsed = MathF.Min(_elapsed + deltaTime, _duration);
         float t = _duration == 0 ? 1 : _elapsed / _duration;
-        float easedT = Ease(t, _to.TransitionType);
+        float easedT = Ease(t, _to.Transition);
 
         return LerpStyle(_from, _to, easedT);
     }
@@ -45,7 +45,7 @@ public class StyleAnimator
             Padding = MathUtils.LerpSize(from.Padding ?? Size.Zero, to.Padding ?? Size.Zero, t),
             BorderColor = MathUtils.LerpColor(from.BorderColor ?? Color.Transparent, to.BorderColor ?? Color.Transparent, t),
             BorderSize = MathUtils.LerpSize(from.BorderSize ?? Size.Zero, to.BorderSize ?? Size.Zero, t),
-            TransitionType = to.TransitionType
+            Transition = to.Transition
         };
 
         return result;