WPF TreeViewItem背景

Question

当TreeViewItem (或应用程序)失去焦点时，如何更改所选TreeView的Background。在这种情况下，默认情况下所选项目的背景为浅灰色。

编辑:在first answer之后尝试:将找不到带有TargetName="Bd"的元素。

<TreeView>
        <TreeView.Resources>
            <Style x:Key="{x:Type TreeViewItem}" TargetType="{x:Type TreeViewItem}">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="{x:Type TreeViewItem}">
                            <ControlTemplate.Triggers>
                                <MultiTrigger>
                                    <MultiTrigger.Conditions>
                                        <Condition Property="IsSelected" Value="True"/>
                                        <Condition Property="IsSelectionActive" Value="False"/>
                                    </MultiTrigger.Conditions>
                                    <Setter TargetName="Bd" Property="Background" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}" />
                                    <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}" />
                                </MultiTrigger>
                            </ControlTemplate.Triggers>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </TreeView.Resources>

        <TreeViewItem Header="Test1" IsExpanded="True">
            <TreeViewItem Header="Test2" />
            <TreeViewItem Header="Test3" />
            <TreeViewItem Header="Test4" />
            <TreeViewItem Header="Test5" />
        </TreeViewItem>
    </TreeView>

Answer 1

您需要修改TreeViewItem的默认样式。具体来说，您需要修改以下触发器：

<Style x:Key="{x:Type TreeViewItem}"
       TargetType="{x:Type TreeViewItem}">
    ...
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TreeViewItem}">
                ...
                <ControlTemplate.Triggers>
                    ...
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="IsSelected"
                                       Value="true"/>
                            <Condition Property="IsSelectionActive"
                                       Value="false"/>
                        </MultiTrigger.Conditions>
                        <Setter TargetName="Bd"
                                Property="Background"
                                Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
                        <Setter Property="Foreground"
                                Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
                    </MultiTrigger>
                    ...
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    ...
</Style>

正如您所看到的，如果项目被聚焦并且选择不是活动的(焦点在其他地方)，则触发器将背景设置为{DynamicResource {x:Static SystemColors.ControlBrushKey}}。

更新：

Aero主题的完整TreeViewItem样式如下所示：

<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>
                    <ToggleButton x:Name="Expander"
                                  Style="{StaticResource ExpandCollapseToggleStyle}"
                                  IsChecked="{Binding Path=IsExpanded,RelativeSource={RelativeSource TemplatedParent}}"
                                  ClickMode="Press"/>
                    <Border Name="Bd"
                            Grid.Column="1"
                            Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}"
                            Padding="{TemplateBinding Padding}"
                            SnapsToDevicePixels="true">
                        <ContentPresenter x:Name="PART_Header"
                                          ContentSource="Header"
                                          HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                          SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                    </Border>
                    <ItemsPresenter x:Name="ItemsHost"
                                    Grid.Row="1"
                                    Grid.Column="1"
                                    Grid.ColumnSpan="2"/>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsExpanded"
                             Value="false">
                        <Setter TargetName="ItemsHost"
                                Property="Visibility"
                                Value="Collapsed"/>
                    </Trigger>
                    <Trigger Property="HasItems"
                             Value="false">
                        <Setter TargetName="Expander"
                                Property="Visibility"
                                Value="Hidden"/>
                    </Trigger>
                    <Trigger Property="IsSelected"
                             Value="true">
                        <Setter TargetName="Bd"
                                Property="Background"
                                Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
                        <Setter Property="Foreground"
                                Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
                    </Trigger>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="IsSelected"
                                       Value="true"/>
                            <Condition Property="IsSelectionActive"
                                       Value="false"/>
                        </MultiTrigger.Conditions>
                        <Setter TargetName="Bd"
                                Property="Background"
                                Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
                        <Setter Property="Foreground"
                                Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
                    </MultiTrigger>
                    <Trigger Property="IsEnabled"
                             Value="false">
                        <Setter Property="Foreground"
                                Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
  <Style.Triggers>
    <Trigger Property="VirtualizingStackPanel.IsVirtualizing"
             Value="true">
      <Setter Property="ItemsPanel">
        <Setter.Value>
          <ItemsPanelTemplate>
            <VirtualizingStackPanel/>
          </ItemsPanelTemplate>
        </Setter.Value>
      </Setter>
    </Trigger>
  </Style.Triggers>
</Style>

为此，您还需要以下代码：

<PathGeometry x:Key="TreeArrow">
    <PathGeometry.Figures>
        <PathFigureCollection>
            <PathFigure IsFilled="True"
                        StartPoint="0 0"
                        IsClosed="True">
                <PathFigure.Segments>
                    <PathSegmentCollection>
                        <LineSegment Point="0 6"/>
                        <LineSegment Point="6 0"/>
                    </PathSegmentCollection>
                </PathFigure.Segments>
            </PathFigure>
        </PathFigureCollection>
    </PathGeometry.Figures>
</PathGeometry>

<Style x:Key="ExpandCollapseToggleStyle"
       TargetType="{x:Type ToggleButton}">
    <Setter Property="Focusable"
            Value="False"/>
    <Setter Property="Width"
            Value="16"/>
    <Setter Property="Height"
            Value="16"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ToggleButton}">
                <Border Width="16"
                        Height="16"
                        Background="Transparent"
                        Padding="5,5,5,5">
                    <Path x:Name="ExpandPath"
                          Fill="Transparent"
                          Stroke="#FF989898"
                          Data="{StaticResource TreeArrow}">
                        <Path.RenderTransform>
                            <RotateTransform Angle="135"
                                             CenterX="3"
                                             CenterY="3"/>
                        </Path.RenderTransform>
                    </Path>
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver"
                             Value="True">
                        <Setter TargetName="ExpandPath"
                                Property="Stroke"
                                Value="#FF1BBBFA"/>
                        <Setter TargetName="ExpandPath"
                                Property="Fill"
                                Value="Transparent"/>
                    </Trigger>

                    <Trigger Property="IsChecked"
                             Value="True">
                        <Setter TargetName="ExpandPath"
                                Property="RenderTransform">
                            <Setter.Value>
                                <RotateTransform Angle="180"
                                                 CenterX="3"
                                                 CenterY="3"/>
                            </Setter.Value>
                        </Setter>
                        <Setter TargetName="ExpandPath"
                                Property="Fill"
                                Value="#FF595959"/>
                        <Setter TargetName="ExpandPath"
                                Property="Stroke"
                                Value="#FF262626"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

在所有这些操作中，您只需要修改您感兴趣的部分(如果选择处于非活动状态，则修改背景颜色)，并将这些样式放置在主窗口中App.xaml的资源部分中。

Answer 2

对于您的特定情况，存在更简单的方法。与ListBox类似，您可以将ControlBrush资源替换为TreeViewItem的使用样式：

<Style TargetType="TreeViewItem">
    <Style.Resources>
        <SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="{x:Static SystemColors.HighlightColor}" Opacity=".4" />
    </Style.Resources>
</Style>

您可以指定任何其他颜色。建议使用不透明度，因为如果您有多个TreeView/ListBox，您可以确定哪一个是焦点。当然，编辑完整样式可以为将来的定制带来更大的灵活性。

使用渐变进行采样：

<Style TargetType="TreeViewItem">
    <Style.Resources>
        <LinearGradientBrush x:Key="{x:Static SystemColors.ControlBrushKey}" EndPoint='0 1'>
            <GradientStop Color='#AA00FF00' />
            <GradientStop Offset='1' Color='#AA007700' />
        </LinearGradientBrush>
        <LinearGradientBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" EndPoint='0 1'>
            <GradientStop Color='#AA00FF00' />
            <GradientStop Offset='1' Color='#AA007700' />
        </LinearGradientBrush>
    </Style.Resources>
</Style>

Answer 3

如果你不想覆盖默认的控制模板，你可以使用textblock为标题定义你自己的模板，并将该模板中的样式应用于textblock本身(在TreeViewItem的默认控制模板中有一个小的填充，所以你也应该将它设置为零以达到像素的完美)。

<TreeView.Resources>
    <Style TargetType="TreeViewItem">
        <Setter Property="Padding" Value="0"/>
        <Setter Property="HeaderTemplate">
            <Setter.Value>
                <DataTemplate>
                    <DataTemplate.Resources>
                        <Style TargetType="TextBlock">
                            <Style.Triggers>
                                <MultiDataTrigger>
                                    <MultiDataTrigger.Conditions>
                                        <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource AncestorType=TreeViewItem}}" Value="True"/>
                                        <Condition Binding="{Binding IsSelectionActive, RelativeSource={RelativeSource AncestorType=TreeViewItem}}" Value="False"/>
                                    </MultiDataTrigger.Conditions>
                                    <Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" />
                                    <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}" />
                                </MultiDataTrigger>
                            </Style.Triggers>
                        </Style>
                    </DataTemplate.Resources>
                    <TextBlock Text="{Binding}"></TextBlock>
                </DataTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</TreeView.Resources>

<TreeViewItem Header="Test1" IsExpanded="True">
    <TreeViewItem Header="Test2" />
    <TreeViewItem Header="Test3" />
    <TreeViewItem Header="Test4" />
    <TreeViewItem Header="Test5" />
</TreeViewItem>

​