DataTriggerBehavior不适用于Enum？

Question

我正在尝试使用DataTriggerBehaviorBehaviors SDK中的一个.但它似乎与枚举无关......或者我做错了什么.

您可以假设DataContext这些示例是这样的(INotifyPropertyChanged已实现,但我不打算在此处显示):

public class MyDataClass
{
    public MyEnum ItemCommand { get; set; }
    public string ItemCommandString { get; set; }
}

public enum MyEnum
{
    EnumValue1
}

_Button.DataContext = new MyDataClass() { ItemCommand = MyEnum.EnumValue1, 
                                          ItemCommandString = "EnumValue1" };

以下代码不起作用(尝试指定枚举值并检查ItemCommand枚举属性):

<ToggleButton x:Name="_Button">
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding ItemCommand}" 
                                  Value="EnumValue1">
            <Core:ChangePropertyAction PropertyName="Command" 
                                       TargetObject="{Binding ElementName=_Button}"
                                       Value="{x:Null}">
            </Core:ChangePropertyAction>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</ToggleButton>

并且此代码(检查枚举资源)也不起作用:

<UserControl.Resources>
    <local:MyEnum x:Key="_MyEnumValue">EnumValue1</local:MyEnum>
</UserControl.Resources>

<ToggleButton x:Name="_Button">
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding ItemCommand}" 
                                  Value="{StaticResource _MyEnumValue}">
            <Core:ChangePropertyAction PropertyName="Command" 
                                       TargetObject="{Binding ElementName=_Button}"
                                       Value="{x:Null}">
            </Core:ChangePropertyAction>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</ToggleButton>

而这段代码(检查字符串)确实有效:

<ToggleButton x:Name="_Button">
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding ItemCommandString}" 
                                  Value="EnumValue1">
            <Core:ChangePropertyAction PropertyName="Command" 
                                       TargetObject="{Binding ElementName=_Button}"
                                       Value="{x:Null}">
            </Core:ChangePropertyAction>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</ToggleButton>

在DataTriggerBehavior Value属性中指定枚举值的正确方法是什么,以便这可以工作？

Answer 1

你可以写一个转换器：

 public class MyEnumConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, string language)
        {
            MyEnum myEnumValue = (MyEnum)value;
            return myEnumValue.ToString();
        }

        public object ConvertBack(object value, Type targetType, object parameter, string language)
        {
            throw new NotImplementedException();
        }
    }

并在 XAML 中使用它：

<ToggleButton x:Name="_Button">
    <Interactivity:Interaction.Behaviors>
        <Core:DataTriggerBehavior Binding="{Binding ItemCommand, Converter={StaticResource MyEnumConverter}}" 
                                  Value="EnumValue1">
            <Core:ChangePropertyAction PropertyName="Command" 
                                       TargetObject="{Binding ElementName=_Button}"
                                       Value="{x:Null}">
            </Core:ChangePropertyAction>
        </Core:DataTriggerBehavior>
    </Interactivity:Interaction.Behaviors>
</ToggleButton>

或者像示例中那样直接绑定到字符串。不幸的是，WinRT 中的 DataTriggerBehavior 比 Windows Phone 8 中的 DataTrigger 更糟糕