WPF实现树形表格控件(TreeListView)

前言

　　本文将探讨如何利用WPF框架实现树形表格控件，该控件不仅能够有效地展示复杂的层级数据，还能够提供丰富的个性化定制选项。我们将介绍如何使用WPF提供的控件、模板、布局、数据绑定等技术来构建这样一个树形表格。

一、运行效果

1.1默认样式

1.2 自定义样式

二、代码实现

2.1 创建自定义控件（TreeListView）

新建一个继承自TreeView的控件，并定义一个类型为ViewBase的View依赖属性，用于在代码中指定列。

public class TreeListView : TreeView
{
        public ViewBase View
        {
            get { return (ViewBase)GetValue(ViewProperty); }
            set { SetValue(ViewProperty, value); }
        }

        public static readonly DependencyProperty ViewProperty =
            DependencyProperty.Register("View", typeof(ViewBase), typeof(TreeListView));
}

2.2 在TreeListView控件模板中处理列头

为了在TreeListView中显示列头，需要在合适的位置添加GridViewHeaderRowPresenter控件，并在Columns属性上绑定我们之前定义的View.Columns属性。下面我们首先来分析TreeView控件模板的代码。

<ControlTemplate TargetType="{x:Type TreeView}">
    <Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" SnapsToDevicePixels="true">
        <ScrollViewer x:Name="_tv_scrollviewer_" Background="{TemplateBinding Background}" CanContentScroll="false" Focusable="false" HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}">
            <ItemsPresenter/>
        </ScrollViewer>
    </Border>
    <ControlTemplate.Triggers>
        <Trigger Property="IsEnabled" Value="false">
            <Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
        </Trigger>
        <Trigger Property="VirtualizingPanel.IsVirtualizing" Value="true">
            <Setter Property="CanContentScroll" TargetName="_tv_scrollviewer_" Value="true"/>
        </Trigger>
    </ControlTemplate.Triggers>
</ControlTemplate>

通过以上代码我们可以看出，只要将GridViewHeaderRowPresenter控件添加到ScrollViewer控件上面即可实现列头功能，但这样会有一个问题，那就是内容宽度超出控件宽度后，鼠标拖动横向滚动条时列头不会跟随下方的数据列表一起滚动。为解决这个问题我们需要将GridViewHeaderRowPresenter放置到ScrollViewer控件模板中，以下为完整代码。

<Style x:Key="{x:Static GridView.GridViewScrollViewerStyleKey}" TargetType="{x:Type ScrollViewer}">
    <Setter Property="Focusable" Value="false" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type ScrollViewer}">
                <Grid Background="{TemplateBinding Background}" SnapsToDevicePixels="true">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition Width="*" />
                        <ColumnDefinition Width="Auto" />
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                        <RowDefinition Height="*" />
                        <RowDefinition Height="Auto" />
                    </Grid.RowDefinitions>

                    <DockPanel Margin="{TemplateBinding Padding}">
                        <ScrollViewer
                                DockPanel.Dock="Top"
                                Focusable="false"
                                HorizontalScrollBarVisibility="Hidden"
                                VerticalScrollBarVisibility="Hidden">
                            <GridViewHeaderRowPresenter
                                    Margin="2,0,2,0"
                                    AllowsColumnReorder="{Binding TemplatedParent.View.AllowsColumnReorder, RelativeSource={RelativeSource TemplatedParent}}"
                                    ColumnHeaderContainerStyle="{Binding TemplatedParent.View.ColumnHeaderContainerStyle, RelativeSource={RelativeSource TemplatedParent}}"
                                    ColumnHeaderContextMenu="{Binding TemplatedParent.View.ColumnHeaderContextMenu, RelativeSource={RelativeSource TemplatedParent}}"
                                    ColumnHeaderStringFormat="{Binding TemplatedParent.View.ColumnHeaderStringFormat, RelativeSource={RelativeSource TemplatedParent}}"
                                    ColumnHeaderTemplate="{Binding TemplatedParent.View.ColumnHeaderTemplate, RelativeSource={RelativeSource TemplatedParent}}"
                                    ColumnHeaderTemplateSelector="{Binding TemplatedParent.View.ColumnHeaderTemplateSelector, RelativeSource={RelativeSource TemplatedParent}}"
                                    ColumnHeaderToolTip="{Binding TemplatedParent.View.ColumnHeaderToolTip, RelativeSource={RelativeSource TemplatedParent}}"
                                    Columns="{Binding TemplatedParent.View.Columns, RelativeSource={RelativeSource TemplatedParent}}"
                                    SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
                        </ScrollViewer>
                        <ScrollContentPresenter
                                x:Name="PART_ScrollContentPresenter"
                                CanContentScroll="{TemplateBinding CanContentScroll}"
                                Content="{TemplateBinding Content}"
                                ContentTemplate="{TemplateBinding ContentTemplate}"
                                KeyboardNavigation.DirectionalNavigation="Local"
                                SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
                    </DockPanel>

                    <ScrollBar
                            x:Name="PART_HorizontalScrollBar"
                            Grid.Row="1"
                            Cursor="Arrow"
                            Maximum="{TemplateBinding ScrollableWidth}"
                            Minimum="0.0"
                            Orientation="Horizontal"
                            ViewportSize="{TemplateBinding ViewportWidth}"
                            Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"
                            Value="{Binding HorizontalOffset, Mode=OneWay, RelativeSource={RelativeSource TemplatedParent}}" />
                    <ScrollBar
                            x:Name="PART_VerticalScrollBar"
                            Grid.Column="1"
                            Cursor="Arrow"
                            Maximum="{TemplateBinding ScrollableHeight}"
                            Minimum="0.0"
                            Orientation="Vertical"
                            ViewportSize="{TemplateBinding ViewportHeight}"
                            Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"
                            Value="{Binding VerticalOffset, Mode=OneWay, RelativeSource={RelativeSource TemplatedParent}}" />
                    <DockPanel
                            Grid.Row="1"
                            Grid.Column="1"
                            Background="{Binding Background, ElementName=PART_VerticalScrollBar}"
                            LastChildFill="false">
                        <Rectangle
                                Width="1"
                                DockPanel.Dock="Left"
                                Fill="White"
                                Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}" />
                        <Rectangle
                                Height="1"
                                DockPanel.Dock="Top"
                                Fill="White"
                                Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}" />
                    </DockPanel>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

<Style TargetType="{x:Type local:TreeListView}">
    <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto" />
    <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
    <Setter Property="ScrollViewer.CanContentScroll" Value="true" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:TreeListView}">
                <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
                    <ScrollViewer Padding="{TemplateBinding Padding}" Style="{StaticResource {x:Static GridView.GridViewScrollViewerStyleKey}}">
                        <ItemsPresenter />
                    </ScrollViewer>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

2.3 在TreeListViewItem模板中处理子项的展开和收缩

新建一个继承自TreeViewItem的类，命名为TreeListViewItem（如有个性化需求，可以在该类中处理），编辑控件模板，在模板中添加以下代码。

<Style TargetType="{x:Type local:TreeListViewItem}">
    <Setter Property="BorderThickness" Value="1" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:TreeListViewItem}">
                <StackPanel>
                    <Border
                            Name="Bd"
                            Padding="{TemplateBinding Padding}"
                            Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}">
                        <GridViewRowPresenter
                                x:Name="PART_Header"
                                Columns="{Binding RelativeSource={RelativeSource AncestorType=local:TreeListView}, Path=View.Columns}"
                                Content="{TemplateBinding Header}" />
                    </Border>
                    <ItemsPresenter x:Name="ItemsHost" />
                </StackPanel>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsExpanded" Value="false">
                        <Setter TargetName="ItemsHost" Property="Visibility" Value="Collapsed" />
                    </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>

                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="extensions:TreeViewItemExtensions.IsMouseDirectlyOverItem" Value="True" />
                        </MultiTrigger.Conditions>
                        <Setter TargetName="Bd" Property="Background" Value="{StaticResource Item.MouseOver.Background}" />
                        <Setter TargetName="Bd" Property="BorderBrush" Value="{StaticResource Item.MouseOver.Border}" />
                    </MultiTrigger>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="Selector.IsSelectionActive" Value="False" />
                            <Condition Property="IsSelected" Value="True" />
                        </MultiTrigger.Conditions>
                        <Setter TargetName="Bd" Property="Background" Value="{StaticResource Item.SelectedInactive.Background}" />
                        <Setter TargetName="Bd" Property="BorderBrush" Value="{StaticResource Item.SelectedInactive.Border}" />
                    </MultiTrigger>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="Selector.IsSelectionActive" Value="True" />
                            <Condition Property="IsSelected" Value="True" />
                        </MultiTrigger.Conditions>
                        <Setter TargetName="Bd" Property="Background" Value="{StaticResource Item.SelectedActive.Background}" />
                        <Setter TargetName="Bd" Property="BorderBrush" Value="{StaticResource Item.SelectedActive.Border}" />
                    </MultiTrigger>
                    <Trigger Property="IsEnabled" Value="False">
                        <Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

此处的核心在于模板中添加了GridViewRowPresenter控件，并在Columns属性上绑定了我们之前定义的View.Columns属性，这样就可以在每一行上面显示列数据。还有一个关键点是ItemsPresenter，它用于显示子项数据，此处命名为ItemsHost，它由属性触发器中的代码来控件展开和收起。以下是属性触发器代码。

<Trigger Property="IsExpanded" Value="false">
    <Setter TargetName="ItemsHost" Property="Visibility" Value="Collapsed" />
</Trigger>

2.4 在单元格模板中控件子项的展开与收起

为了达到展开和收起的效果，需要在首列的单元格中控制TreeListViewItem的IsExpanded属性。以下为完整代码。

<DataTemplate x:Key="ExpandCellTemplate">
    <DockPanel>
        <ToggleButton
                            x:Name="Expander"
                            Margin="{Binding Path=Level, Converter={StaticResource LevelIndentConverter}, RelativeSource={RelativeSource AncestorType={x:Type TreeListViewItem}}}"
                            ClickMode="Press"
                            IsChecked="{Binding Path=IsExpanded, RelativeSource={RelativeSource AncestorType={x:Type TreeListViewItem}}}"
                            Style="{StaticResource ExpandCollapseToggleStyle}" />
        <TextBlock Text="{Binding Property1}" />
    </DockPanel>
    <DataTemplate.Triggers>
        <DataTrigger Binding="{Binding Path=HasItems, RelativeSource={RelativeSource AncestorType={x:Type TreeListViewItem}}}" Value="False">
            <Setter TargetName="Expander" Property="Visibility" Value="Hidden" />
        </DataTrigger>
    </DataTemplate.Triggers>
</DataTemplate>

其关键代码为

IsChecked="{Binding Path=IsExpanded, RelativeSource={RelativeSource AncestorType={x:Type TreeListViewItem}}}"

2.5 控件使用

<TreeListView ItemsSource="{Binding Collection}">
    <TreeListView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding Collection, IsAsync=True}" />
    </TreeListView.ItemTemplate>
    <TreeListView.View>
        <GridView>
            <GridViewColumn CellTemplate="{StaticResource ExpandCellTemplate}" Header="Property1" />
            <GridViewColumn DisplayMemberBinding="{Binding Property2}" Header="Property2" />
            <GridViewColumn DisplayMemberBinding="{Binding Property3}" Header="Property3" />
            <GridViewColumn DisplayMemberBinding="{Binding Property4}" Header="Property4" />
            <GridViewColumn DisplayMemberBinding="{Binding Property5}" Header="Property5" />
            <GridViewColumn DisplayMemberBinding="{Binding Property6}" Header="Property6" />
            <GridViewColumn DisplayMemberBinding="{Binding Property7}" Header="Property7" />
            <GridViewColumn DisplayMemberBinding="{Binding Property8}" Header="Property8" />
            <GridViewColumn DisplayMemberBinding="{Binding Property9}" Header="Property9" />
            <GridViewColumn DisplayMemberBinding="{Binding Property10}" Header="Property10" />
            <GridViewColumn DisplayMemberBinding="{Binding Property11}" Header="Property11" />
            <GridViewColumn DisplayMemberBinding="{Binding Property12}" Header="Property12" />
        </GridView>
    </TreeListView.View>
</TreeListView>