xaml - DataTriggerBehavior 不适用于枚举？

Question

我正在尝试使用 DataTriggerBehavior来自行为 SDK。但它似乎不适用于枚举......否则我做错了什么。

您可以假设 DataContext这些示例是这样的(INotifyPropertyChanged 已实现，但我不打算在这里展示):

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" };

这是不起作用的代码(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 中指定枚举值的正确方法是什么？ Value属性(property)，这样这将起作用吗？

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>

或直接绑定(bind)到示例中的字符串。不幸的是，WinRT 中的 DataTriggerBehavior 比 Windows Phone 8 中的 DataTrigger 更糟糕