Preventing debug asserts when using debug builds of WPF

Author: batzen

Fluent.Ribbon/Converters/ObjectToImageConverter.cs

@@ -246,7 +246,36 @@ private object CreateMultiBinding(IServiceProvider serviceProvider)
             multiBinding.Bindings.Add(this.TargetVisualBinding);
         }
 
-        return multiBinding.ProvideValue(serviceProvider);
+        return multiBinding.ProvideValue(new ServiceProviderWrapper(serviceProvider));
+    }
+
+    private class ServiceProviderWrapper : IServiceProvider, IProvideValueTarget
+    {
+        private readonly IServiceProvider serviceProvider;
+
+        public ServiceProviderWrapper(IServiceProvider serviceProvider)
+        {
+            this.serviceProvider = serviceProvider;
+        }
+
+        /// <inheritdoc />
+        public object? GetService(Type serviceType)
+        {
+            if (serviceType == typeof(IProvideValueTarget))
+            {
+                return this;
+            }
+
+            return this.serviceProvider.GetService(serviceType);
+        }
+
+        /// <inheritdoc />
+        public object? TargetObject => ((IProvideValueTarget)this.serviceProvider).TargetObject is DependencyObject dpo
+            ? dpo
+            : null;
+
+        /// <inheritdoc />
+        public object TargetProperty => ((IProvideValueTarget)this.serviceProvider).TargetProperty;
     }
 
     private object? Convert(object? value, Visual? targetVisual, Size desiredSize, Type targetType)
@@ -366,9 +395,17 @@ private object CreateMultiBinding(IServiceProvider serviceProvider)
             {
                 var type = expression.GetType();
                 var method = type.GetMethod("GetValue", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
+                var field = type.GetField("_targetObject", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
 
-                if (method is not null)
+                if (method is not null
+                    && field is not null)
                 {
+                    // We have to set the target object. otherwise we might hit debug asserts.
+                    if (field.GetValue(expression) is null)
+                    {
+                        field.SetValue(expression, targetVisual);
+                    }
+
                     var valueFromExpression = method.Invoke(expression, new object[]
                     {
                         targetVisual,