How do I inject a custom UITypeEditor for all properties of a closed-source type?

Question

I want to avoid placing an EditorAttribute on every instance of a certain type that I\'ve written a custom UITypeEditor for.

I can\'t place an EditorAttribute on t

Answer 1

Marc's solution bluntly applies the EditorAttribute to the Bar type globally. If you have a delicate disposition, you might rather annotate properties of a specific instances. Alas, that isn't possible with TypeDescriptor.AddAttributes

My solution was to write a wrapper ViewModel, which copies properties from T, annotating some with extra attributes. Suppose we have a variable datum of type Report, we'd use it like this

        var pretty = ViewModel.DressUp(datum);
        pretty.PropertyAttributeReplacements[typeof(Smiley)] = new List() { new EditorAttribute(typeof(SmileyEditor),typeof(UITypeEditor))};
        propertyGrid1.SelectedObject = pretty;

Where ViewModel is defined:

public class ViewModel : CustomTypeDescriptor
{
    private T _instance;
    private ICustomTypeDescriptor _originalDescriptor;
    public ViewModel(T instance, ICustomTypeDescriptor originalDescriptor) : base(originalDescriptor)
    {
        _instance = instance;
        _originalDescriptor = originalDescriptor;
        PropertyAttributeReplacements = new Dictionary>();
    }

    public static ViewModel DressUp(T instance)
    {
        return new ViewModel(instance, TypeDescriptor.GetProvider(instance).GetTypeDescriptor(instance));
    }

    /// 

    /// Most useful for changing EditorAttribute and TypeConvertorAttribute
    /// 
    public IDictionary> PropertyAttributeReplacements {get; set; } 

    public override PropertyDescriptorCollection GetProperties (Attribute[] attributes)
    {
        var properties = base.GetProperties(attributes).Cast();

        var bettered = properties.Select(pd =>
            {
                if (PropertyAttributeReplacements.ContainsKey(pd.PropertyType))
                {
                    return TypeDescriptor.CreateProperty(typeof(T), pd, PropertyAttributeReplacements[pd.PropertyType].ToArray());
                }
                else
                {
                    return pd;
                }
            });
        return new PropertyDescriptorCollection(bettered.ToArray());
    }

    public override PropertyDescriptorCollection GetProperties()
    {
        return GetProperties(null);
    }
}

As defined above, this substitutes properties of a specific type, but you can substitute properties by name if you need the greater resolution.