减少使用水平 space 的 TreeView

Question

我如何控制展开的 TreeViewItems 使用的水平 space 以便树视图可以占用更少 space？可以单独通过样式来完成还是必须完全重新制作树视图才能控制这些样式属性？

Answer 1

您看到的项目是由父级 TreeViewItem 的 ItemsPresenter 布局的。这意味着要更改子项的缩进，您必须更改 ItemsPresenter 在布局中的位置。

为此，您必须覆盖 TreeViewItem 的默认值 ControlTemplate。找到 ItemsPresenter 并给它一个负左 Margin 以减少缩进或一个正左边距以增加子项的缩进。

以下Style摘自Microsoft Docs: TreeView ControlTemplate Example。在那里您可以找到以下 Style 所依赖的所有资源。

关键是在名为“ItemsHost”的ItemsPresenter上设置一个左负数Margin：

<ItemsPresenter x:Name="ItemsHost"
                ...
                Margin="-12,0,0,0" />

完整的 TreeViewItemStyle（没有资源）：

<Style x:Key="{x:Type TreeViewItem}"
       TargetType="{x:Type TreeViewItem}">
  <Setter Property="Background"
          Value="Transparent" />
  <Setter Property="HorizontalContentAlignment"
          Value="{Binding Path=HorizontalContentAlignment,
    RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}" />
  <Setter Property="VerticalContentAlignment"
          Value="{Binding Path=VerticalContentAlignment,
    RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}" />
  <Setter Property="Padding"
          Value="1,0,0,0" />
  <Setter Property="Foreground"
          Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" />
  <Setter Property="FocusVisualStyle"
          Value="{StaticResource TreeViewItemFocusVisual}" />
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="{x:Type TreeViewItem}">
        <Grid>
          <Grid.ColumnDefinitions>
            <ColumnDefinition MinWidth="19"
                              Width="Auto" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
          </Grid.ColumnDefinitions>
          <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition />
          </Grid.RowDefinitions>
          <VisualStateManager.VisualStateGroups>
            <VisualStateGroup x:Name="SelectionStates">
              <VisualState x:Name="Selected">
                <Storyboard>
                  <ColorAnimationUsingKeyFrames Storyboard.TargetName="Bd"
                                                Storyboard.TargetProperty="(Panel.Background).
                    (SolidColorBrush.Color)"
                                                >
                    <EasingColorKeyFrame KeyTime="0"
                                         Value="{StaticResource SelectedBackgroundColor}" />
                  </ColorAnimationUsingKeyFrames>
                </Storyboard>
              </VisualState>
              <VisualState x:Name="Unselected" />
              <VisualState x:Name="SelectedInactive">
                <Storyboard>
                  <ColorAnimationUsingKeyFrames Storyboard.TargetName="Bd"
                                                Storyboard.TargetProperty="(Panel.Background).
                    (SolidColorBrush.Color)">
                    <EasingColorKeyFrame KeyTime="0"
                                         Value="{StaticResource SelectedUnfocusedColor}" />
                  </ColorAnimationUsingKeyFrames>
                </Storyboard>
              </VisualState>
            </VisualStateGroup>
            <VisualStateGroup x:Name="ExpansionStates">
              <VisualState x:Name="Expanded">
                <Storyboard>
                  <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)"
                                                 Storyboard.TargetName="ItemsHost">
                    <DiscreteObjectKeyFrame KeyTime="0"
                                            Value="{x:Static Visibility.Visible}" />
                  </ObjectAnimationUsingKeyFrames>
                </Storyboard>
              </VisualState>
              <VisualState x:Name="Collapsed" />
            </VisualStateGroup>
          </VisualStateManager.VisualStateGroups>
          <ToggleButton x:Name="Expander"
                        Style="{StaticResource ExpandCollapseToggleStyle}"
                        ClickMode="Press"
                        IsChecked="{Binding IsExpanded, 
            RelativeSource={RelativeSource TemplatedParent}}"/>
          <Border x:Name="Bd"
                  Grid.Column="1"
                  Background="{TemplateBinding Background}"
                  BorderBrush="{TemplateBinding BorderBrush}"
                  BorderThickness="{TemplateBinding BorderThickness}"
                  Padding="{TemplateBinding Padding}">
            <ContentPresenter x:Name="PART_Header"
                              ContentSource="Header"
                              HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"/>
          </Border>


          <!-- Host of the child items -->
          <ItemsPresenter x:Name="ItemsHost"
                          Grid.Row="1"
                          Grid.Column="1"
                          Grid.ColumnSpan="2"
                          Visibility="Collapsed"
                          Margin="-12,0,0,0" />
        </Grid>
        <ControlTemplate.Triggers>
          <Trigger Property="HasItems"
                   Value="false">
            <Setter TargetName="Expander"
                    Property="Visibility"
                    Value="Hidden" />
          </Trigger>
          <MultiTrigger>
            <MultiTrigger.Conditions>
              <Condition Property="HasHeader"
                         Value="false" />
              <Condition Property="Width"
                         Value="Auto" />
            </MultiTrigger.Conditions>
            <Setter TargetName="PART_Header"
                    Property="MinWidth"
                    Value="75" />
          </MultiTrigger>
          <MultiTrigger>
            <MultiTrigger.Conditions>
              <Condition Property="HasHeader"
                         Value="false" />
              <Condition Property="Height"
                         Value="Auto" />
            </MultiTrigger.Conditions>
            <Setter TargetName="PART_Header"
                    Property="MinHeight"
                    Value="19" />
          </MultiTrigger>
        </ControlTemplate.Triggers>
      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>

减少使用水平 space 的 TreeView

Decrease used horizontal space of TreeView

c#

wpf

xaml

treeview