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wpfxaml

DockPanel inside TreeViewItem.Header don't fill all the space

I want to have 2 Textblocks in my TreeViewItem.Header. So I though it works like this:

<TreeViewItem>
    <TreeViewItem.Header>
       <DockPanel LastChildFill="False" HorizontalAlignment="Stretch">
            <TextBlock Text="Pizza" DockPanel.Dock="Left"/>
            <TextBlock Text="5,00 €" DockPanel.Dock="Right"/>
       </DockPanel>
    </TreeViewItem.Header>
</TreeViewItem>

But the DockPanel don't fill all the Space which is available in TreeViewItem.Header. I tried to Use HorizontalAlignment="Stretch", but this hasn't any effect.

Is there an Attribute to make this Work?

I have a picture where can u see the problem better: Image

Solution

  • If you want the header of a TreeView to stretch horizontally, you should override the ControlTemplate:

    <TreeViewItem HorizontalContentAlignment="Stretch">
    <TreeViewItem.Template>
        <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" ClickMode="Press" IsChecked="{Binding IsExpanded, RelativeSource={RelativeSource TemplatedParent}}" />
                <Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Grid.Column="2" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
                    <ContentPresenter x:Name="PART_Header" ContentSource="Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                </Border>
                <ItemsPresenter x:Name="ItemsHost" Grid.ColumnSpan="2" Grid.Column="1" Grid.Row="1"/>
            </Grid>
            <ControlTemplate.Triggers>
                <Trigger Property="IsExpanded" Value="false">
                    <Setter Property="Visibility" TargetName="ItemsHost" Value="Collapsed"/>
                </Trigger>
                <Trigger Property="HasItems" Value="false">
                    <Setter Property="Visibility" TargetName="Expander" Value="Hidden"/>
                </Trigger>
                <Trigger Property="IsSelected" Value="true">
                    <Setter Property="Background" TargetName="Bd" 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 Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightBrushKey}}"/>
                    <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.InactiveSelectionHighlightTextBrushKey}}"/>
                </MultiTrigger>
                <Trigger Property="IsEnabled" Value="false">
                    <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
                </Trigger>
            </ControlTemplate.Triggers>
        </ControlTemplate>
    </TreeViewItem.Template>
    <TreeViewItem.Header>
        <DockPanel LastChildFill="False">
            <TextBlock Text="Pizza" DockPanel.Dock="Left"/>
            <TextBlock Text="5,00 €" DockPanel.Dock="Right"/>
        </DockPanel>
    </TreeViewItem.Header>
</TreeViewItem>