wpf - 动态宽度绑定(bind)到自定义组合框中使用的下拉列表(弹出窗口)

Question

我正在使用带有样式的自定义组合框，我想通过编码动态设置弹出窗口的宽度，以便自动调整弹出窗口的宽度

所以我想像第二张图片一样动态地更改 Popup(无论 ComboBox 的大小如何)我使用的样式如下

<Style x:Key="ComboBoxStyle" TargetType="{x:Type ComboBox}">
        <Setter Property="Foreground" Value="#666666"/>
        <Setter Property="FontFamily" Value="Arial"/>
        <Setter Property="FontSize" Value="13"/>
        <Setter Property="Height" Value="28"/>
        <Setter Property="BorderThickness" Value="1.5"/>
        <Setter Property="Padding" Value="4,3"/>
        <Setter Property="Margin" Value="5"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ComboBox}">
                    <Grid>                            
                        <Popup Margin="1" x:Name="PART_Popup" AllowsTransparency="true" IsOpen="{Binding Path=IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" Placement="Bottom" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Grid.ColumnSpan="2" Width="{Binding ActualWidth,RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Grid}}">
                            <Border Name="DropDownBorder" Width="Auto" Height="Auto" BorderThickness="1,0,1,1" CornerRadius="0,0,4,4" BorderBrush="#FFbbbbbb">
                                <Border.Background>
                                    <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                        <GradientStop Color="White" Offset="0" />
                                        <GradientStop Color="#FFE9E9E9" Offset="1" />
                                    </LinearGradientBrush>
                                </Border.Background>
                                <ScrollViewer CanContentScroll="true">
                                    <ItemsPresenter  />
                                </ScrollViewer>
                            </Border>
                        </Popup>                           
                        <ToggleButton Style="{StaticResource cmbToggle}" Grid.ColumnSpan="2" IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"/>
                        <ContentPresenter HorizontalAlignment="Left" Margin="5,0,0,0" VerticalAlignment="Center" IsHitTestVisible="false" Content="{TemplateBinding SelectionBoxItem}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"/>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

<Style x:Key="cmbToggle" TargetType="{x:Type ToggleButton}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ToggleButton}">
                    <Border Name="cmbBorder" CornerRadius="3" BorderBrush="#FFaaaaaa" BorderThickness="1.5">
                        <Border.Background>
                            <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                                <GradientStop Color="White" Offset="0" />
                                <GradientStop Color="#FFE9E9E9" Offset="1" />
                            </LinearGradientBrush>
                        </Border.Background>
                        <Border BorderBrush="#FFaaaaaa" BorderThickness="1,0,0,0" Width="20" HorizontalAlignment="Right">                                
                            <Polygon Name="pol" Fill="#FF787878" Points="4,9 8,14 12,9" Stroke="#FF787878" StrokeThickness="0" Margin="1 1 0 0">
                            </Polygon>
                        </Border>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsChecked" Value="True">
                            <Setter Property="CornerRadius" TargetName="cmbBorder" Value="4,4,0,0"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

所以我的想法是动态更改弹出窗口的宽度(组合框宽度 - 切换按钮宽度 = 弹出窗口宽度)。我在 App.xaml 中编写了样式如何做到这一点，请帮助我。提前致谢。

Answer 1

好的，所以在您的 ToggleButton Style 中我们可以看到 Border 持有 Polygon 箭头是 20 in 宽度。这是要从 Popup

中删除的 Width

因此我们可以这样做:

首先在 ComboBox ControlTemplate 中的 Grid 添加 2 列

<ControlTemplate TargetType="{x:Type ComboBox}">
  <Grid>
    <!-- New Bit -->
    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="*" />
      <ColumnDefinition Width="20" />
    </Grid.ColumnDefinitions>
    <!-- End of New Bit -->
    <Popup x:Name="PART_Popup"
            Grid.ColumnSpan="2"
    ...

然后更新Popup的Width为

<Popup x:Name="PART_Popup"
        Grid.ColumnSpan="2"
        Width="{Binding Path=ColumnDefinitions[0].ActualWidth,
                        RelativeSource={RelativeSource Mode=FindAncestor,
                                                      AncestorType=Grid}}"
...

您的 Style 已经在适当的控件上提到了 ColumnSpan，因此不需要其他任何东西。这应该会为您提供所需的输出。