无法通过数据触发设置ContentTemplate

Question

我希望ContentTemplate根据DataTrigger中的值而变化。
是的，我考虑过使用DataTemplateSelector，但现在我需要一个DataTrigger或者更好地说是一个MultiDataTrigger。
请看下面的示例应用程序，DataTemplate没有改变：

<Window x:Class="Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:src="clr-namespace:WpfApplication1">
    <StackPanel>
        <CheckBox IsChecked="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}" Content="BoolProperty"/>
        <ContentControl Content="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}">
            <ContentControl.ContentTemplate>
                <DataTemplate>
                    <CheckBox IsChecked="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}" Content="Template 1"/>
                </DataTemplate>
            </ContentControl.ContentTemplate>
            <ContentControl.Resources>
                <DataTemplate x:Key="Template2">
                    <CheckBox IsChecked="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}" Content="Template 2"/>
                </DataTemplate>
            </ContentControl.Resources>
            <ContentControl.Style>
                <Style TargetType="ContentControl">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}" Value="True">
                            <Setter Property="ContentTemplate" Value="{StaticResource Template2}"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </ContentControl.Style>
        </ContentControl>
        <Button Name="btnSwitch" Content="Switch"/>
    </StackPanel>
</Window>

---

Partial Class Window1
    Public Property BoolProperty() As Boolean
        Get
            Return GetValue(BoolPropertyProperty)
        End Get
        Set(ByVal value As Boolean)
            SetValue(BoolPropertyProperty, value)
        End Set
    End Property
    Public Shared ReadOnly BoolPropertyProperty As DependencyProperty = DependencyProperty.Register("BoolProperty", GetType(Boolean), GetType(Window1), New FrameworkPropertyMetadata(False))

    Private Sub btnSwitch_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnSwitch.Click
        BoolProperty = Not BoolProperty
    End Sub
End Class

- Shimmy Weitzhandler

Answer 1

我知道问题的提问者不再需要这个答案，但我觉得还是要回答一下，以防其他人遇到相同的问题。

这个问题中Xaml的唯一问题是ContentTemplate在ContentControl上被显式设置而不是在样式中设置，这会覆盖触发器。将它设置在样式中可以解决这个问题。

<ContentControl Content="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}">
    <ContentControl.Resources>
        <DataTemplate x:Key="Template2">
            <CheckBox IsChecked="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}" Content="Template 2"/>
        </DataTemplate>
    </ContentControl.Resources>
    <ContentControl.Style>
        <Style TargetType="ContentControl">
            <Setter Property="ContentTemplate">
                <Setter.Value>
                    <DataTemplate>
                        <CheckBox IsChecked="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}" Content="Template 1"/>
                    </DataTemplate>
                </Setter.Value>
            </Setter>
            <Style.Triggers>
                <DataTrigger Binding="{Binding BoolProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type src:Window1}}}" Value="True">
                    <Setter Property="ContentTemplate" Value="{StaticResource Template2}"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </ContentControl.Style>
</ContentControl>

- Fredrik Hedblad

Answer 2

这是我的解决方案：

<ContentControl Content="{Binding SomeBool}">
  <ContentControl.Resources>
    <DataTemplate x:Key="PinkTemplate">
      <TextBlock Text="{Binding}" Background="Pink" />
    </DataTemplate>
    <DataTemplate x:Key="LimeTemplate">
      <TextBlock Text="{Binding}" Background="Lime" />
    </DataTemplate>
  </ContentControl.Resources>
  <ContentControl.ContentTemplate>
    <DataTemplate>
      <ContentControl Name="cc"
                      Content="{Binding}"
                      ContentTemplate="{StaticResource PinkTemplate}" />
      <DataTemplate.Triggers>
        <DataTrigger Binding="{Binding}" Value="True">
          <Setter TargetName="cc" 
                  Property="ContentTemplate"
                  Value="{StaticResource LimeTemplate}" />
        </DataTrigger>
      </DataTemplate.Triggers>
    </DataTemplate>
  </ContentControl.ContentTemplate>
</ContentControl>

请注意，我的DataTemplate是另一个ContentControl，这使得我的DataTemplate.Triggers能够操作该（嵌套）ContentControl的ContentTemplate。

- itowlson

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如果有帮助的话：除非您将StaticResource更改为DynamicResource，否则可能会出现异常。 - DeeStackOverflow