Question

I have a custom UITypeEditor that is in use for Colour Selection with my program using the propertygrid, but I can’t seem to get it to activate if I just expose system.drawing.color. I need to wrap the Color with a CustomType before it will invoke my UITypeEditor.

Note the Property TheColour it works. The Colour doesn’t.

When I open the propertyGrid, I can see GetEditStyle is called via both methods, but when it comes to EditValue it is only called when you select TheColour in the propertygrid. The Normal Colour dropdown is shown when you select Colour Property

What am I missing?

<CategoryAttribute("Order Colour"), _
 Browsable(True), _
 DisplayName("The Colour"), _
 Description("The background colour for orders from this terminal"), _
EditorAttribute(GetType(IKMDependency.ColourSelectorEditor), _ 
GetType(System.Drawing.Design.UITypeEditor))> _
Public Property TheColour() As MyColour
    Get
        Return mMyColor
    End Get
    Set(ByVal value As MyColour)
        If value.Colour <> mMyColor.Colour Then
            mColor = value.Colour
            mMyColor = value
            mIsDirty = True
        End If
    End Set
End Property

<CategoryAttribute("Order Colour"), _
 Browsable(True), _
 DisplayName("Colour"), _
 Description("The background colour for orders from this terminal"), _
EditorAttribute(GetType(IKMDependency.ColourSelectorEditor), _ 
GetType(System.Drawing.Design.UITypeEditor))> _
Public Property Colour() As Color
    Get
        Return mColor
    End Get
    Set(ByVal value As Color)
        If mColor <> value Then
            mColor = value
            mMyColor = New MyColour(mColor)
            mIsDirty = True
        End If
    End Set
End Property

Answer 1

The problem is that it is noticing that the associated TypeConverter supports enumerated values. We need to disable that; note we can also inherit from the default implementations to get things like the color preview painting (examples in C#, but should be easy to translate):

class MyColorEditor : ColorEditor {
    public override UITypeEditorEditStyle GetEditStyle(
        ITypeDescriptorContext context) {
         return UITypeEditorEditStyle.Modal;
    }
    public override object  EditValue(
       ITypeDescriptorContext context, IServiceProvider provider, object value) {
        MessageBox.Show(
              "We could show an editor here, but you meant Green, right?");
       return Color.Green;
    }
}
class MyColorConverter : ColorConverter { // reference: System.Drawing.Design.dll
    public override bool GetStandardValuesSupported(
            ITypeDescriptorContext context) {
        return false;
    }
}
class TestObject
{
    [Category("Order Colour"), Browsable(true), DisplayName("Colour")]
    [Description("The background colour for orders from this terminal")]
    [Editor(typeof(MyColorEditor), typeof(UITypeEditor))]
    [TypeConverter(typeof(MyColorConverter))]
    public Color Colour {get;set;}
}

If you want this to apply to all Color properties, there is also a way to do it such that you don’t need to decorate every property; somewhere during your app’s initialization code, execute:

TypeDescriptor.AddAttributes(typeof(Color),
    new EditorAttribute(typeof(MyColorEditor), typeof(UITypeEditor)),
    new TypeConverterAttribute(typeof(MyColorConverter)));