隐藏WPF Expander控件的箭头

Question

当使用WPF Expander控件时，它与默认的“向上”和“向下”箭头键一起显示。有没有办法隐藏那些上下箭头？

更新：

我通过创建一个ControlTemplate设法移除了箭头，但现在扩展功能也消失了：

<ContentPresenter Content="{TemplateBinding Expander.Header}"></ContentPresenter>
            <ContentPresenter Content="{TemplateBinding Expander.Content}"></ContentPresenter>



<Expander Template="{StaticResource ExpanderControlTemplate}" IsExpanded="False" Cursor="Hand">             

                <Expander.Header>
                <Border Style="{StaticResource FeedTitleStyle}">
                <DockPanel Width="Auto">
                    <TextBlock DockPanel.Dock="Left" FontSize="16" Text="IronRuby in Action!" />                   
                </DockPanel>           

            </Border>                 
                </Expander.Header>
                <Expander.Content>                    
                    <TextBlock Text="This is the decriprion!" />
                </Expander.Content>

            </Expander>

Answer 1

不幸的是，标题的ExpanderTemplate中的ContentPresenter与箭头在同一个网格中，所以仅仅设置HeaderTemplate对我们没有帮助。

使用Mole，我们可以看到ToggleButton有一个表示圆的椭圆，一个表示箭头的路径，还有一个ContentPresenter，它显示了您为Header属性设置的内容。

​

现在我们知道了Expander的实际布局，有几种方法可以修改它。为扩展器创建一个全新的ControlTemplate，或者获取我们想要移除的部分并移除/隐藏它们。

更新：掌握了Blend，在为扩展器生成模板后，它几乎只需要通过并删除每个ToggleButton样式中的椭圆和路径。

<Style x:Key="ExpanderHeaderFocusVisual">
    <Setter Property="Control.Template">
    <Setter.Value>
        <ControlTemplate>
            <Border>
                <Rectangle SnapsToDevicePixels="true"
                           Margin="0"
                           Stroke="Black"
                           StrokeDashArray="1 2"
                           StrokeThickness="1" />
            </Border>
        </ControlTemplate>
    </Setter.Value>
    </Setter>
</Style>

<Style x:Key="ExpanderDownHeaderStyle"
       TargetType="{x:Type ToggleButton}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ToggleButton}">
                <Border Padding="{TemplateBinding Padding}">
                    <Grid SnapsToDevicePixels="False"
                          Background="Transparent">
                        <ContentPresenter SnapsToDevicePixels="True"
                                          HorizontalAlignment="Left"
                                          VerticalAlignment="Center"
                                          RecognizesAccessKey="True" />
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="ExpanderRightHeaderStyle"
       TargetType="{x:Type ToggleButton}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ToggleButton}">
                <Border Padding="{TemplateBinding Padding}">
                    <Grid SnapsToDevicePixels="False"
                          Background="Transparent">
                        <ContentPresenter SnapsToDevicePixels="True"
                                          HorizontalAlignment="Center"
                                          VerticalAlignment="Top"
                                          RecognizesAccessKey="True" />
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="ExpanderUpHeaderStyle"
       TargetType="{x:Type ToggleButton}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ToggleButton}">
                <Border Padding="{TemplateBinding Padding}">
                    <Grid SnapsToDevicePixels="False"
                          Background="Transparent">
                        <ContentPresenter SnapsToDevicePixels="True"
                                          HorizontalAlignment="Left"
                                          VerticalAlignment="Center"
                                          RecognizesAccessKey="True" />
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="ExpanderLeftHeaderStyle"
       TargetType="{x:Type ToggleButton}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ToggleButton}">
                <Border Padding="{TemplateBinding Padding}">
                    <Grid SnapsToDevicePixels="False"
                          Background="Transparent">
                        <ContentPresenter SnapsToDevicePixels="True"
                                          HorizontalAlignment="Center"
                                          VerticalAlignment="Top"
                                          RecognizesAccessKey="True" />
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
<Style x:Key="ArrowlessExpanderTemplate"
       TargetType="{x:Type Expander}">
    <Setter Property="Foreground"
            Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" />
    <Setter Property="Background"
            Value="Transparent" />
    <Setter Property="HorizontalContentAlignment"
            Value="Stretch" />
    <Setter Property="VerticalContentAlignment"
            Value="Stretch" />
    <Setter Property="BorderBrush"
            Value="Transparent" />
    <Setter Property="BorderThickness"
            Value="1" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type Expander}">
                <Border SnapsToDevicePixels="true"
                        Background="{TemplateBinding Background}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        CornerRadius="3">
                    <DockPanel>
                        <ToggleButton FontFamily="{TemplateBinding FontFamily}"
                                      FontSize="{TemplateBinding FontSize}"
                                      FontStretch="{TemplateBinding FontStretch}"
                                      FontStyle="{TemplateBinding FontStyle}"
                                      FontWeight="{TemplateBinding FontWeight}"
                                      Foreground="{TemplateBinding Foreground}"
                                      HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                                      Padding="{TemplateBinding Padding}"
                                      VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
                                      FocusVisualStyle="{StaticResource ExpanderHeaderFocusVisual}"
                                      Margin="1"
                                      MinHeight="0"
                                      MinWidth="0"
                                      x:Name="HeaderSite"
                                      Style="{StaticResource ExpanderDownHeaderStyle}"
                                      Content="{TemplateBinding Header}"
                                      ContentTemplate="{TemplateBinding HeaderTemplate}"
                                      ContentTemplateSelector="{TemplateBinding HeaderTemplateSelector}"
                                      DockPanel.Dock="Top"
                                      IsChecked="{Binding Path=IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" />
                        <ContentPresenter Focusable="false"
                                          Visibility="Collapsed"
                                          HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                          Margin="{TemplateBinding Padding}"
                                          x:Name="ExpandSite"
                                          VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                                          DockPanel.Dock="Bottom" />
                    </DockPanel>
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsExpanded"
                             Value="true">
                        <Setter Property="Visibility"
                                TargetName="ExpandSite"
                                Value="Visible" />
                    </Trigger>
                    <Trigger Property="ExpandDirection"
                             Value="Right">
                        <Setter Property="DockPanel.Dock"
                                TargetName="ExpandSite"
                                Value="Right" />
                        <Setter Property="DockPanel.Dock"
                                TargetName="HeaderSite"
                                Value="Left" />
                        <Setter Property="Style"
                                TargetName="HeaderSite"
                                Value="{StaticResource ExpanderRightHeaderStyle}" />
                    </Trigger>
                    <Trigger Property="ExpandDirection"
                             Value="Up">
                        <Setter Property="DockPanel.Dock"
                                TargetName="ExpandSite"
                                Value="Top" />
                        <Setter Property="DockPanel.Dock"
                                TargetName="HeaderSite"
                                Value="Bottom" />
                        <Setter Property="Style"
                                TargetName="HeaderSite"
                                Value="{StaticResource ExpanderUpHeaderStyle}" />
                    </Trigger>
                    <Trigger Property="ExpandDirection"
                             Value="Left">
                        <Setter Property="DockPanel.Dock"
                                TargetName="ExpandSite"
                                Value="Left" />
                        <Setter Property="DockPanel.Dock"
                                TargetName="HeaderSite"
                                Value="Right" />
                        <Setter Property="Style"
                                TargetName="HeaderSite"
                                Value="{StaticResource ExpanderLeftHeaderStyle}" />
                    </Trigger>
                    <Trigger Property="IsEnabled"
                             Value="false">
                        <Setter Property="Foreground"
                                Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

此外，我们还可以创建一个AttachedProperty，并将箭头和圆部分设置为折叠。

这是我们的AttachedProperty：

public class AttachedProperties
{
    #region HideExpanderArrow AttachedProperty

    [AttachedPropertyBrowsableForType(typeof(Expander))]
    public static bool GetHideExpanderArrow(DependencyObject obj)
    {
        return (bool)obj.GetValue(HideExpanderArrowProperty);
    }

    [AttachedPropertyBrowsableForType(typeof(Expander))]
    public static void SetHideExpanderArrow(DependencyObject obj, bool value)
    {
        obj.SetValue(HideExpanderArrowProperty, value);
    }

    // Using a DependencyProperty as the backing store for HideExpanderArrow.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty HideExpanderArrowProperty =
        DependencyProperty.RegisterAttached("HideExpanderArrow", typeof(bool), typeof(AttachedProperties), new UIPropertyMetadata(false, OnHideExpanderArrowChanged));

    private static void OnHideExpanderArrowChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
    {
        Expander expander = (Expander)o;

        if (expander.IsLoaded)
        {
            UpdateExpanderArrow(expander, (bool)e.NewValue);
        }
        else
        {
            expander.Loaded += new RoutedEventHandler((x, y) => UpdateExpanderArrow(expander, (bool)e.NewValue));
        }
    }

    private static void UpdateExpanderArrow(Expander expander, bool visible)
    {
        Grid headerGrid =
            VisualTreeHelper.GetChild(
                VisualTreeHelper.GetChild(
                        VisualTreeHelper.GetChild(
                            VisualTreeHelper.GetChild(
                                VisualTreeHelper.GetChild(
                                    expander,
                                    0),
                                0),
                            0),
                        0),
                    0) as Grid;

        headerGrid.Children[0].Visibility = visible ? Visibility.Collapsed : Visibility.Visible; // Hide or show the Ellipse
        headerGrid.Children[1].Visibility = visible ? Visibility.Collapsed : Visibility.Visible; // Hide or show the Arrow
        headerGrid.Children[2].SetValue(Grid.ColumnProperty, visible ? 0 : 1); // If the Arrow is not visible, then shift the Header Content to the first column.
        headerGrid.Children[2].SetValue(Grid.ColumnSpanProperty, visible ? 2 : 1); // If the Arrow is not visible, then set the Header Content to span both rows.
        headerGrid.Children[2].SetValue(ContentPresenter.MarginProperty, visible ? new Thickness(0) : new Thickness(4,0,0,0)); // If the Arrow is not visible, then remove the margin from the Content.
    } 

    #endregion
}

我只是直接转到包含“箭头”和标题内容的网格，而不是试图通过名称查找控件，所以如果您还将扩展器重新模板化到不同的结构中，这将不会完全起作用。一旦我们找到了包含的网格，我们可以将箭头和圆圈设置为折叠，并确保标题内容一直移到左边。

要使用附加属性，我们可以在XAML中的元素上设置它：

<StackPanel>
    <Expander x:Name="uiExpander" 
              local:AttachedProperties.HideExpanderArrow="True">
        <Expander.Header>
            <Border>
                <DockPanel Width="Auto">
                    <TextBlock DockPanel.Dock="Left"
                               FontSize="16"
                               Text="IronRuby in Action!" />
                </DockPanel>
            </Border>
        </Expander.Header>
        <Expander.Content>
            <TextBlock Text="This is the decriprion!" />
        </Expander.Content>
    </Expander>

    <Button Content="Click to Show/Hide Expander Arrow"
            Click="Button_Click" />

</StackPanel>

在代码中：

void Button_Click(object sender, RoutedEventArgs e)
{
    uiExpander.SetValue(
        AttachedProperties.HideExpanderArrowProperty, 
        !(bool)uiExpander.GetValue(AttachedProperties.HideExpanderArrowProperty));
}