ShrlAlgoToolkit/Melskin/Controls/TreeGrid.xaml

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:assists="clr-namespace:Melskin.Assists"
    xmlns:controls="clr-namespace:Melskin.Controls"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <Style TargetType="{x:Type controls:TreeGrid}">
        <Setter Property="Background" Value="{DynamicResource BackgroundLayoutBrush}" />
        <Setter Property="assists:ControlAssist.CornerRadius" Value="4" />
        <Setter Property="BorderBrush" Value="{DynamicResource BorderNormalBrush}" />
        <Setter Property="BorderThickness" Value="1" />
        <Setter Property="Foreground" Value="{DynamicResource TextPrimaryBrush}" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type controls:TreeGrid}">
                    <Grid>
                        <Border Background="{TemplateBinding Background}" CornerRadius="{TemplateBinding assists:ControlAssist.CornerRadius}">
                            <Border.OpacityMask>
                                <VisualBrush>
                                    <VisualBrush.Visual>
                                        <!--  定义遮罩形状：黑色代表可见区域，圆角与外部一致  -->
                                        <Border
                                            Background="Black"
                                            CornerRadius="{Binding CornerRadius, RelativeSource={RelativeSource AncestorType=Border}}"
                                            Height="{Binding ActualHeight, RelativeSource={RelativeSource AncestorType=Border}}"
                                            SnapsToDevicePixels="True"
                                            Width="{Binding ActualWidth, RelativeSource={RelativeSource AncestorType=Border}}" />
                                    </VisualBrush.Visual>
                                </VisualBrush>
                            </Border.OpacityMask>
                            <DockPanel>
                                <!--  1. 表头区域，放置在顶部  -->
                                <!--  - 用 ScrollViewer 包裹以同步滚动  -->
                                <!--  - 隐藏自己的滚动条，因为它只是一个“跟随者”  -->
                                <ScrollViewer
                                    Background="Transparent"
                                    DockPanel.Dock="Top"
                                    HorizontalScrollBarVisibility="Hidden"
                                    VerticalScrollBarVisibility="Disabled"
                                    x:Name="PART_HeaderScrollViewer">
                                    <GridViewHeaderRowPresenter Columns="{Binding Columns, RelativeSource={RelativeSource TemplatedParent}}" />
                                </ScrollViewer>

                                <!--  2. 内容区域，占据剩余空间  -->
                                <!--  - 将所有相关属性从外层 TreeGrid 传递给内部的 TreeView  -->
                                <TreeView
                                    Background="{DynamicResource ControlBackgroundNormalBrush}"
                                    BorderThickness="0"
                                    ItemContainerStyle="{Binding ItemContainerStyle, RelativeSource={RelativeSource TemplatedParent}}"
                                    ItemTemplate="{Binding ItemTemplate, RelativeSource={RelativeSource TemplatedParent}}"
                                    ItemsSource="{Binding ItemsSource, RelativeSource={RelativeSource TemplatedParent}}"
                                    assists:ControlAssist.CornerRadius="0"
                                    x:Name="PART_ContentTreeView">
                                    <!--  可选：为了性能，可以启用虚拟化  -->
                                    <TreeView.ItemsPanel>
                                        <ItemsPanelTemplate>
                                            <VirtualizingStackPanel />
                                        </ItemsPanelTemplate>
                                    </TreeView.ItemsPanel>
                                </TreeView>
                            </DockPanel>
                        </Border>
                        <Border
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}"
                            CornerRadius="{TemplateBinding assists:ControlAssist.CornerRadius}"
                            IsHitTestVisible="False" />
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>