Make Merge a method of Style.

TODO.md

@@ -99,7 +99,7 @@
   - ~~Style sheet~~
   - ~~Add style settings for UI panels (for buttons, labels, etc.).~~
   - ~~Parse StyleSheet from TOML file.~~
-  - Style variables
   - Animated styles
+  - (stretch goal) Style variables
   - Find a way to reference external assets in the style (fonts, textures).
   - Create a default style for widgets.

Voile/Source/UI/Style.cs

@@ -20,6 +20,24 @@ public class Style
     public Color? BorderColor { get; set; }
     public float CornerRadius { get; set; }
     public Color? TextColor { get; set; }
+
+    /// <summary>
+    /// 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>
+    /// <returns>A merged <see cref="Style"/>.</returns>
+    public Style Merge(Style overrideStyle)
+    {
+        return new Style
+        {
+            BackgroundColor = overrideStyle.BackgroundColor != default ? overrideStyle.BackgroundColor : BackgroundColor,
+            TextColor = overrideStyle.TextColor != default ? overrideStyle.TextColor : TextColor,
+            Padding = overrideStyle.Padding != default ? overrideStyle.Padding : Padding,
+            BorderSize = overrideStyle.BorderSize != default ? overrideStyle.BorderSize : BorderSize,
+            BorderColor = overrideStyle.BorderColor != default ? overrideStyle.BorderColor : BorderColor,
+        };
+    }
 }
 
 public class StyleSheetLoader : ResourceLoader<StyleSheet>
@@ -88,25 +106,13 @@ public class StyleSheetLoader : ResourceLoader<StyleSheet>
             var subKey = string.Join('.', parts.Take(i));
             if (allStyles.TryGetValue(subKey, out var parentStyle))
             {
-                merged = MergeStyles(merged, parentStyle);
+                merged = merged.Merge(parentStyle);
             }
         }
 
         return merged;
     }
 
-    private Style MergeStyles(Style baseStyle, Style overrideStyle)
-    {
-        return new Style
-        {
-            BackgroundColor = overrideStyle.BackgroundColor != default ? overrideStyle.BackgroundColor : baseStyle.BackgroundColor,
-            TextColor = overrideStyle.TextColor != default ? overrideStyle.TextColor : baseStyle.TextColor,
-            Padding = overrideStyle.Padding != default ? overrideStyle.Padding : baseStyle.Padding,
-            BorderSize = overrideStyle.BorderSize != default ? overrideStyle.BorderSize : baseStyle.BorderSize,
-            BorderColor = overrideStyle.BorderColor != default ? overrideStyle.BorderColor : baseStyle.BorderColor,
-        };
-    }
-
     private readonly TomlDataReader _reader = new();
 }