Fix MvxColorValueConverter not working (#4807)

MvvmCross.Plugins/Color/MvxColorValueConverter.cs

@@ -1,44 +1,35 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MS-PL license.
 // See the LICENSE file in the project root for more information.
-
-using System;
+#nullable enable
 using System.Globalization;
 using MvvmCross.Converters;
 using MvvmCross.UI;
 
-namespace MvvmCross.Plugin.Color
-{
-#nullable enable
-    public abstract class MvxColorValueConverter : MvxValueConverter
-    {
-        private readonly IMvxNativeColor? _nativeColor;
+namespace MvvmCross.Plugin.Color;
 
-        protected MvxColorValueConverter()
-        {
-            Mvx.IoCProvider?.TryResolve<IMvxNativeColor>(out _nativeColor);
-        }
+public abstract class MvxColorValueConverter : MvxValueConverter
+{
+    private readonly Lazy<IMvxNativeColor?> _nativeColor = new(() => Mvx.IoCProvider?.Resolve<IMvxNativeColor>());
 
-        protected abstract System.Drawing.Color Convert(object value, object? parameter, CultureInfo? culture);
+    protected abstract System.Drawing.Color Convert(object value, object? parameter, CultureInfo? culture);
 
-        public sealed override object Convert(object value, Type? targetType, object? parameter,
-                                       CultureInfo? culture)
-        {
-            return _nativeColor?.ToNative(Convert(value, parameter, culture)) ?? MvxBindingConstant.UnsetValue;
-        }
+    public sealed override object Convert(object value, Type? targetType, object? parameter,
+        CultureInfo? culture)
+    {
+        return _nativeColor.Value?.ToNative(Convert(value, parameter, culture)) ?? MvxBindingConstant.UnsetValue;
     }
+}
 
-    public abstract class MvxColorValueConverter<T> : MvxColorValueConverter
+public abstract class MvxColorValueConverter<T> : MvxColorValueConverter
+{
+    protected sealed override System.Drawing.Color Convert(object value, object? parameter, CultureInfo? culture)
     {
-        protected sealed override System.Drawing.Color Convert(object value, object? parameter, CultureInfo? culture)
-        {
-            if (value is T t)
-                return Convert(t, parameter, culture);
+        if (value is T t)
+            return Convert(t, parameter, culture);
 
-            return default;
-        }
-
-        protected abstract System.Drawing.Color Convert(T value, object? parameter, CultureInfo? culture);
+        return default;
     }
-#nullable restore
+
+    protected abstract System.Drawing.Color Convert(T value, object? parameter, CultureInfo? culture);
 }

MvvmCross/Binding/Binders/MvxNamedInstanceRegistryFiller.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Linq;
 using System.Reflection;
+using Microsoft.Extensions.Logging;
 using MvvmCross.Base;
 using MvvmCross.IoC;
 
@@ -88,9 +89,10 @@ where type.IsConventional()
                     MvxBindingLog.Trace("Registering value converter {0}:{1}", pair.Name, pair.Type.Name);
                     registry.AddOrOverwrite(pair.Name, converter);
                 }
-                catch (Exception)
+                catch (Exception ex)
                 {
-                    // ignore this
+                    MvxBindingLog.Instance?.LogError(ex, "Failed to register {Name} from {Type}", pair.Name,
+                        pair.Type.Name);
                 }
             }
         }

Projects/Playground/Playground.Core/Converters/TextToColorValueConverter.cs

@@ -0,0 +1,24 @@
+using System.Drawing;
+using System.Globalization;
+using MvvmCross.Plugin.Color;
+
+namespace Playground.Core.Converters;
+
+// Sample converter to show issue found in GH issue #4803
+public sealed class TextToColorValueConverter : MvxColorValueConverter
+{
+    protected override Color Convert(object value, object parameter, CultureInfo culture)
+    {
+        if (value is not string stringValue)
+            return Color.Magenta;
+
+        return stringValue switch
+        {
+            "I am green!" => Color.Green,
+            "I am yellow!" => Color.Yellow,
+            "I am brown!" => Color.Brown,
+            "I am orange!" => Color.Orange,
+            _ => Color.Black
+        };
+    }
+}

Projects/Playground/Playground.Core/Playground.Core.csproj

@@ -15,6 +15,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <ProjectReference Include="..\..\..\MvvmCross.Plugins\Color\MvvmCross.Plugin.Color.csproj" />
     <ProjectReference Include="..\..\..\MvvmCross.Plugins\JsonLocalization\MvvmCross.Plugin.JsonLocalization.csproj" />
     <ProjectReference Include="..\..\..\MvvmCross.Plugins\Json\MvvmCross.Plugin.Json.csproj" />
     <ProjectReference Include="..\..\..\MvvmCross.Plugins\Messenger\MvvmCross.Plugin.Messenger.csproj" />

Projects/Playground/Playground.Droid/Resources/layout/activity_converters.xml

@@ -36,7 +36,7 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_gravity="center"
-        local:MvxBind="Text ColorText; TextColor NativeColor(TextColor)"/>
+        local:MvxBind="Text ColorText; TextColor TextToColor(ColorText)"/>
 
     <Button
         android:layout_width="match_parent"