如何定位嵌套 ControlTemplate 中的元素

Question

在自定义组合框的样式中，我想更改 ToggleButton 的 ControlTemplate 中 Border 元素的 Background 属性 ComboBox.IsEditable 属性设置为 true 但运行进入此针对 Border:

的错误

Cannot find the Trigger target. (The target must appear before any Setters, Triggers, or Conditions that use it.)

我尝试过的事情：

按名称定位边界：TargetName="Border"
将边框定位为 ToggleButton 的子项：TargetName="ToggleButton.Border"

网上唯一能找到的资料是这样说的：

TargetName operates only within the one ControlTemplate section

但我不确定这是否与我的情况相关，因为 ToggleButtons 的 ControlTemplate 是我的自定义组合框 ControlTemplate.

的子项

样式（为简洁起见删除了不相关的代码）

<Style x:Key="{x:Type local:CustomComboBox}" TargetType="{x:Type local:CustomComboBox}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:CustomComboBox}">
                <Grid>
                    <ToggleButton x:Name="ToggleButton" Focusable="False" ClickMode="Press"
                                  VerticalContentAlignment="Center"
                                  IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}">
                        <ToggleButton.Template>
                            <ControlTemplate TargetType="{x:Type ToggleButton}">
                                <Grid>
                                    <Border x:Name="Border" Grid.ColumnSpan="2"
                                            Background="{Binding Background, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:CustomComboBox}}"/>
                                </Grid>
                            </ControlTemplate>
                        </ToggleButton.Template>
                    </ToggleButton>                 
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="ComboBox.IsEditable" Value="True">
                        <Setter Property="Background" TargetName="ToggleButton.Border" Value="Green"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Answer 1

不是在嵌套模板上设置值，而是相反，通过 [= 在嵌套模板中绑定父 CustomComboBox 的 IsEditable 属性 17=]。如果属性是 True.

，请使用 DataTrigger 将 Border 的颜色设置为 Green

<Style x:Key="{x:Type local:CustomComboBox}" TargetType="{x:Type local:CustomComboBox}">
   <Setter Property="Template">
      <Setter.Value>
         <ControlTemplate TargetType="{x:Type local:CustomComboBox}">
            <Grid>
               <ToggleButton x:Name="ToggleButton" Focusable="False" ClickMode="Press"
                             VerticalContentAlignment="Center"
                             IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}">
                  <ToggleButton.Template>
                     <ControlTemplate TargetType="{x:Type ToggleButton}">
                        <Grid>
                           <Border x:Name="Border" Grid.ColumnSpan="2"
                                   Background="{Binding Background, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:CustomComboBox}}"/>
                        </Grid>
                        <ControlTemplate.Triggers>
                           <DataTrigger Binding="{Binding IsEditable, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:CustomComboBox}}" Value="True">
                              <Setter TargetName="Border" Property="Background" Value="Green"/>
                           </DataTrigger>
                        </ControlTemplate.Triggers>
                     </ControlTemplate>
                  </ToggleButton.Template>
               </ToggleButton>                 
            </Grid>
         </ControlTemplate>
      </Setter.Value>
   </Setter>
</Style>

如何定位嵌套 ControlTemplate 中的元素

How to target elements in nested ControlTemplates

c#

wpf

xaml

controltemplate