列表框项目的 DataTemplate 中 IsSelected 的 WPF 触发器
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WPF Trigger for IsSelected in a DataTemplate for ListBox items
提问by TimothyP
I have a listbox, and I have the following ItemTemplate for it:
我有一个列表框，我有以下 ItemTemplate：
<DataTemplate x:Key="ScenarioItemTemplate">
<Border Margin="5,0,5,0"
Background="#FF3C3B3B"
BorderBrush="#FF797878"
BorderThickness="2"
CornerRadius="5">
<DockPanel>
<DockPanel DockPanel.Dock="Top"
Margin="0,2,0,0">
<Button HorizontalAlignment="Left"
DockPanel.Dock="Left"
FontWeight="Heavy"
Foreground="White" />
<Label Content="{Binding Path=Name}"
DockPanel.Dock="Left"
FontWeight="Heavy"
Foreground="white" />
<Label HorizontalAlignment="Right"
Background="#FF3C3B3B"
Content="X"
DockPanel.Dock="Left"
FontWeight="Heavy"
Foreground="White" />
</DockPanel>
<ContentControl Name="designerContent"
Visibility="Collapsed"
MinHeight="100"
Margin="2,0,2,2"
Content="{Binding Path=DesignerInstance}"
Background="#FF999898">
</ContentControl>
</DockPanel>
</Border>
</DataTemplate>
As you can see the ContentControl has Visibility set to collapsed.
如您所见，ContentControl 已将 Visibility 设置为折叠。
I need to define a trigger that causes the Visibility to be set to "Visible"
我需要定义一个触发器，导致可见性设置为“可见”
when the ListItem is selected, but I can't figure it out.
当 ListItem 被选中时，但我无法弄清楚。
Any ideas?
有任何想法吗？
UPDATE: Of course I could simply duplicate the DataTemplate and add triggers to the ListBox in question to use either one or the other, but I want to prevent duplicating this code.
更新：当然，我可以简单地复制 DataTemplate 并将触发器添加到有问题的 ListBox 以使用其中一个或另一个，但我想防止复制此代码。
回答by Matt Hamilton
You can style your ContentControl such that a trigger fires when its container (the ListBoxItem) becomes selected:
您可以设置 ContentControl 样式，以便在其容器（ListBoxItem）被选中时触发触发器：
<ContentControl
x:Name="designerContent"
MinHeight="100"
Margin="2,0,2,2"
Content="{Binding Path=DesignerInstance}"
Background="#FF999898">
<ContentControl.Style>
<Style TargetType="{x:Type ContentControl}">
<Setter Property="Visibility" Value="Collapsed"/>
<Style.Triggers>
<DataTrigger
Binding="{Binding
RelativeSource={RelativeSource
Mode=FindAncestor,
AncestorType={x:Type ListBoxItem}},
Path=IsSelected}"
Value="True">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ContentControl.Style>
</ContentControl>
Alternatively, I think you can add the trigger to the template itself and reference the control by name. I don't know this technique well enough to type it from memory and assume it'll work, but it's something like this:
或者，我认为您可以将触发器添加到模板本身并按名称引用控件。我不太了解这种技术，无法从内存中键入它并假设它会起作用，但它是这样的：
<DataTemplate x:Key="ScenarioItemTemplate">
<DataTemplate.Triggers>
<DataTrigger
Binding="{Binding
RelativeSource={RelativeSource
Mode=FindAncestor,
AncestorType={x:Type ListBoxItem}},
Path=IsSelected}"
Value="True">
<Setter
TargetName="designerContent"
Property="Visibility"
Value="Visible"/>
</DataTrigger>
</DataTemplate.Triggers>
...
</DataTemplate>
回答by TimothyP
@Matt, Thank you!!!
@马特，谢谢！！！
Just had to add a trigger for IsSelected == false as well, and now it works like a charm!
只需要为 IsSelected == false 添加一个触发器，现在它就像一个魅力！
<ContentControl.Style>
<Style TargetType="{x:Type ContentControl}">
<Setter Property="Visibility" Value="Collapsed"/>
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBoxItem}},Path=IsSelected}" Value="True">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBoxItem}},Path=IsSelected}" Value="False">
<Setter Property="Visibility" Value="Collapsed"/>
</DataTrigger>
</Style.Triggers>
</Style>
