WPF實現樹形表格控制項(TreeListView)

前言本文將探討如何利用WPF框架實現樹形表格控制項，該控制項不僅能夠有效地展示覆雜的層級數據，還能夠提供豐富的個性化定製選項。我們將介紹如何使用WPF提供的控制項、模板、佈局、數據綁定等技術來構建這樣一個樹形表格。一、運行效果 1.1預設樣式 1.2 自定義樣式二、代碼實現 2.1 創建自定義控制項（ ...

前言

　　本文將探討如何利用WPF框架實現樹形表格控制項，該控制項不僅能夠有效地展示覆雜的層級數據，還能夠提供豐富的個性化定製選項。我們將介紹如何使用WPF提供的控制項、模板、佈局、數據綁定等技術來構建這樣一個樹形表格。

一、運行效果

1.1預設樣式

1.2 自定義樣式

二、代碼實現

2.1 創建自定義控制項（TreeListView）

新建一個繼承自TreeView的控制項，並定義一個類型為ViewBase的View依賴屬性，用於在代碼中指定列。

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控制項模板中處理列頭

為了在TreeListView中顯示列頭，需要在合適的位置添加GridViewHeaderRowPresenter控制項，併在Columns屬性上綁定我們之前定義的View.Columns屬性。下麵我們首先來分析TreeView控制項模板的代碼。

<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>

通過以上代碼我們可以看出，只要將GridViewHeaderRowPresenter控制項添加到ScrollViewer控制項上面即可實現列頭功能，但這樣會有一個問題，那就是內容寬度超出控制項寬度後，滑鼠拖動橫向滾動條時列頭不會跟隨下方的數據列表一起滾動。為解決這個問題我們需要將GridViewHeaderRowPresenter放置到ScrollViewer控制項模板中，以下為完整代碼。

<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模板中處理子項的展開和收縮

新建一個繼承自TreeViewItem的類，命名為TreeListViewItem（如有個性化需求，可以在該類中處理），編輯控制項模板，在模板中添加以下代碼。

<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>

此處的核心在於模板中添加了GridViewRowPresenter控制項，併在Columns屬性上綁定了我們之前定義的View.Columns屬性，這樣就可以在每一行上面顯示列數據。還有一個關鍵點是ItemsPresenter，它用於顯示子項數據，此處命名為ItemsHost，它由屬性觸發器中的代碼來控制項展開和收起。以下是屬性觸發器代碼。

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

2.4 在單元格模板中控制項子項的展開與收起

為了達到展開和收起的效果，需要在首列的單元格中控制TreeListViewItem的IsExpanded屬性。以下為完整代碼。

<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>

其關鍵代碼為

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

2.5 控制項使用

<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