Xceed属性网格无法完全查看或单击选择空值

Question

我正在使用带有数据绑定的Xceed PropertyGrid和AutoGenerateProperties = true。我有如下所述的可空属性导致奇怪的UI行为。

网格允许我单击值Yes和No，但null选项稍微被属性网格隐藏，并且不允许我单击它以选择它。如果我选择是并使用向上箭头键我可以选择它。 Microsoft属性网格已满显示空选项，并允许我单击它。

我做错了什么或这是一个错误？我在GitHub问题中问过，但对我的issue没有回应。

YesNo? _compressed;
[CategoryAttribute("Package")]
[Description("Set to 'yes' to have compressed files in the source. This attribute cannot be set for merge modules. ")]
public YesNo? Compressed { get { return _compressed; } set { _compressed = value; RaisePropertyChangedEvent("Compressed"); } }

Answer 1

这不是一个真正的错误。如果你想将default(YesNo?)的值显示为空的string或null，你需要定义你想以某种方式显示它的方式。你可以通过创建自己的自定义编辑器来完成：

public class CustomEditor：Xceed.Wpf.Toolkit.PropertyGrid.Editors.ComboBoxEditor {

protected override IValueConverter CreateValueConverter()
{
    return new CustomValueConverter<T>();
}

protected override ComboBox CreateEditor()
{
    ComboBox comboBox = base.CreateEditor();
    FrameworkElementFactory textBlock = new FrameworkElementFactory(typeof(TextBlock));
    textBlock.SetBinding(TextBlock.TextProperty, new Binding(".") { Converter = new CustomValueConverter<T>() });
    comboBox.ItemTemplate = new DataTemplate() { VisualTree = textBlock };
    return comboBox;
}

protected override IEnumerable CreateItemsSource(Xceed.Wpf.Toolkit.PropertyGrid.PropertyItem propertyItem)
{
    return new string[1] { CustomValueConverter<T>.Null }
        .Concat(Enum.GetValues(typeof(T)).OfType<T>().Select(x => x.ToString()));
}

}

public class CustomValueConverter：IValueConverter {internal const string Null =“”; public object Convert（object value，System.Type targetType，object parameter，CultureInfo culture）{if（value == null）return null;

    return value.ToString();
}

public object ConvertBack(object value, System.Type targetType, object parameter, CultureInfo culture)
{
    string s = value?.ToString();
    if (s == Null)
        return null;

    return Enum.Parse(typeof(T), s);
}

}

用法：

YesNo? _compressed;
[CategoryAttribute("Package")]
[Description("Set to 'yes' to have compressed files in the source. This attribute cannot be set for merge modules. ")]
[Editor(typeof(CustomEditor<YesNo>), typeof(CustomEditor<YesNo>))]
public YesNo? Compressed { get { return _compressed; } set { _compressed = value; RaisePropertyChangedEvent("Compressed"); } }