added AbstractThemePlugin to make plugin implementations more error p…

…roof (#29)

README.md

@@ -205,19 +205,18 @@ After this, you need to register this class in the builder:
 As we do not want to force you to use a specific WinForms control library, we currently only support styling of standard controls and controls from our [winforms-stylable-controls](https://github.com/Assorted-Development/winforms-stylable-controls) project.
 As we understand you may want to also style other controls, we support adding specialised plugins to handle styling of a specific type of control. To do this, you need to implement ``:
 ```csharp
-    internal class MyCustomControlThemePlugin : IThemePlugin
+    internal class MyCustomControlThemePlugin : AbstractThemePlugin<MyCustomControl>
     {
-        public void Apply(Control control, AbstractTheme theme)
+        protected override void ApplyPlugin(MyCustomControl mcc, AbstractTheme theme)
         {
-            MyCustomControl mcc = (MyCustomControl)control;
             //style control based on the colors available in the Theme
         }
     }
 ```
 At last, you just need to register it for the correct type:
 ```csharp
  ThemeRegistryHolder.GetBuilder()
-     .AddThemePlugin<MyCustomControl>(new MyCustomControlThemePlugin())
+     .AddThemePlugin(new MyCustomControlThemePlugin())
      .Build();
 ```
 

WinFormsThemes/TestProject/AbstractThemeTest.cs

@@ -1,4 +1,4 @@
-using System.Windows.Forms;
+using System.Windows.Forms;
 using WinFormsThemes;
 using WinFormsThemes.Themes;
 
@@ -13,7 +13,7 @@ public void PluginShouldBeCalledForExactType()
             ThemePlugin plugin = new();
             IThemeRegistry registry = ThemeRegistryHolder.GetBuilder()
                             .SetLoggerFactory(LoggerFactory)
-                            .AddThemePlugin<Button>(plugin)
+                            .AddThemePlugin(plugin)
                             .Build();
             using Button button = new();
             registry.GetTheme()?.Apply(button);
@@ -26,7 +26,7 @@ public void PluginShouldNotBeCalledForDifferentType()
             ThemePlugin plugin = new();
             IThemeRegistry registry = ThemeRegistryHolder.GetBuilder()
                             .SetLoggerFactory(LoggerFactory)
-                            .AddThemePlugin<Button>(plugin)
+                            .AddThemePlugin(plugin)
                             .Build();
             using Form form = new();
             registry.GetTheme()?.Apply(form);
@@ -38,7 +38,7 @@ public void PluginShouldNotBeCalledForSubType()
         {
             ThemePlugin plugin = new();
             IThemeRegistry registry = ThemeRegistryHolder.GetBuilder().SetLoggerFactory(LoggerFactory)
-                            .AddThemePlugin<Button>(plugin)
+                            .AddThemePlugin(plugin)
                             .Build();
             using MyCustomButton button = new();
             registry.GetTheme()?.Apply(button);
@@ -48,11 +48,11 @@ public void PluginShouldNotBeCalledForSubType()
         private class MyCustomButton : Button
         { }
 
-        private class ThemePlugin : IThemePlugin
+        private class ThemePlugin : AbstractThemePlugin<Button>
         {
             public bool WasCalled { get; private set; }
 
-            public void Apply(Control control, AbstractTheme theme)
+            protected override void ApplyPlugin(Button button, AbstractTheme theme)
             {
                 WasCalled = true;
             }

WinFormsThemes/TestProject/ThemeRegistryBuilderTest.cs

@@ -11,7 +11,7 @@ public class ThemeRegistryBuilderTest : AbstractTestClass
         public void AddingThemePluginsShouldWork()
         {
             IThemeRegistry registry = ThemeRegistryHolder.GetBuilder().SetLoggerFactory(LoggerFactory)
-                            .AddThemePlugin<Button>(new ThemePlugin())
+                            .AddThemePlugin(new ThemePlugin())
                             .Build();
             Assert.AreEqual(1, registry.GetTheme()?.ThemePlugins?.Count);
             Assert.AreEqual(typeof(ThemePlugin), registry.GetTheme()?.ThemePlugins?[typeof(Button)]?.GetType());
@@ -21,8 +21,8 @@ public void AddingThemePluginsShouldWork()
         public void AddingThemePluginTwiceShouldThrow()
         {
             IThemeRegistryBuilder registry = ThemeRegistryHolder.GetBuilder().SetLoggerFactory(LoggerFactory)
-                            .AddThemePlugin<Button>(new ThemePlugin());
-            InvalidOperationException ex = Assert.ThrowsException<InvalidOperationException>(() => registry.AddThemePlugin<Button>(new ThemePlugin()));
+                            .AddThemePlugin(new ThemePlugin());
+            InvalidOperationException ex = Assert.ThrowsException<InvalidOperationException>(() => registry.AddThemePlugin(new ThemePlugin()));
             Assert.AreEqual("ThemePlugin for Button already added", ex.Message);
         }
 
@@ -67,9 +67,9 @@ public void DefaultsShouldBeAddedWhenNotSet()
             Assert.AreEqual(0, registry.GetTheme(DefaultDarkTheme.THEME_NAME)?.AdvancedCapabilities?.Count);
         }
 
-        private class ThemePlugin : IThemePlugin
+        private class ThemePlugin : AbstractThemePlugin<Button>
         {
-            public void Apply(Control control, AbstractTheme theme)
+            protected override void ApplyPlugin(Button button, AbstractTheme theme)
             { }
         }
     }

WinFormsThemes/WinFormsThemes/ThemeConfig/IThemeRegistryBuilder.cs

@@ -10,9 +10,8 @@ public interface IThemeRegistryBuilder
         /// <summary>
         /// Add a plugin to handle additional controls for Themes that support it
         /// </summary>
-        /// <typeparam name="T">the Control to handle</typeparam>
         /// <param name="plugin">the plugin handling the theming</param>
-        IThemeRegistryBuilder AddThemePlugin<T>(IThemePlugin plugin) where T : Control;
+        IThemeRegistryBuilder AddThemePlugin(IThemePlugin plugin);
 
         /// <summary>
         /// return the final IThemeRegistry

WinFormsThemes/WinFormsThemes/ThemeConfig/ThemeRegistryBuilder.cs

@@ -41,9 +41,9 @@ public ThemeRegistryBuilder()
             _logger = new Logger<IThemeRegistryBuilder>(_loggerFactory);
         }
 
-        public IThemeRegistryBuilder AddThemePlugin<T>(IThemePlugin plugin) where T : Control
+        public IThemeRegistryBuilder AddThemePlugin(IThemePlugin plugin)
         {
-            Type t = typeof(T);
+            Type t = plugin.GetSupportedType();
             if (_themePlugins.ContainsKey(t))
             {
                 _logger.LogError("ThemePlugin for {ThemeName} already added", t.Name);

WinFormsThemes/WinFormsThemes/Themes/AbstractThemePlugin.cs

@@ -0,0 +1,27 @@
+
+namespace WinFormsThemes.Themes
+{
+    /// <summary>
+    /// helper implementation to make implementing <see cref="IThemePlugin"/> easier
+    /// </summary>
+    /// <typeparam name="T">the control type this plugin supports</typeparam>
+    public abstract class AbstractThemePlugin<T> : IThemePlugin where T : Control
+    {
+        public void Apply(Control control, AbstractTheme theme)
+        {
+            ApplyPlugin((T)control, theme);
+        }
+
+        /// <summary>
+        /// should be implemented by the plugin to style the given control
+        /// </summary>
+        /// <param name="control">the control to style</param>
+        /// <param name="theme">the theme to be applied</param>
+        protected abstract void ApplyPlugin(T control, AbstractTheme theme);
+
+        public Type GetSupportedType()
+        {
+            return typeof(T);
+        }
+    }
+}

WinFormsThemes/WinFormsThemes/Themes/IThemePlugin.cs

@@ -1,4 +1,4 @@
-namespace WinFormsThemes.Themes
+namespace WinFormsThemes.Themes
 {
     /// <summary>
     /// Interface for all Theme Plugins
@@ -11,5 +11,9 @@ public interface IThemePlugin
         /// <param name="control"></param>
         /// <param name="theme"></param>
         void Apply(Control control, AbstractTheme theme);
+        /// <summary>
+        /// Returns the Control type that this plugin supports
+        /// </summary>
+        Type GetSupportedType();
     }
-}
+}