TreeView in ComboBox

在网上有很多人在问如何实现ComboBox中嵌套一个TreeView。在查了一些资料后，综合大家的意见。我做了一个简单的实例。

可以从这里下载：

 

主要的解决办法：

ComboBox主要有两部分组成，一个ToggleButton，一个Popup。通过重新设置一个Popup，可以很容易的添加一个TreeView。

另外，需要将选择的Node表示在ToggleButton中，也需要重新定义一个ToggleButton，并奖显示的内容与TreeView.SelectedItem.Header帮顶。

如果需要有编辑功能，需要另外再加一个TextBox在ToggleButton上。下面是主要的ComboBox Style。具体的内容可以从这里下载

 1            <Style x:Key="{x:Type ComboBox}" TargetType="ComboBox">
 2                <Setter Property="SnapsToDevicePixels" Value="true"/>
 3                <Setter Property="OverridesDefaultStyle" Value="true"/>
 4                <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
 5                <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
 6                <Setter Property="ScrollViewer.CanContentScroll" Value="true"/>
 7                <Setter Property="MinWidth" Value="120"/>
 8                <Setter Property="MinHeight" Value="20"/>
 9                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="ComboBox">
                            <Grid>
                                <ToggleButton Name="ToggleButton" 
                                              Template="{StaticResource ComboBoxToggleButton}" 
                                              Grid.Column="2" 
                                              Focusable="false"
                                              IsChecked="{Binding Path=IsDropDownOpen,Mode=TwoWay,RelativeSource={RelativeSource TemplatedParent}}"
                                              ClickMode="Press">
                                </ToggleButton>
                                <ContentPresenter Name="ContentSite"
                                                  IsHitTestVisible="False" 
                                                  Content="{Binding ElementName=tv, Mode=OneWay, Path=SelectedItem, Converter={StaticResource TreeViewSelectionConverter}}"
                                                  ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
                                                  ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
                                                  Margin="3,3,23,3"
                                                  VerticalAlignment="Center"
                                                  HorizontalAlignment="Left" />
                                <TextBox x:Name="PART_EditableTextBox"
                                         Style="{x:Null}" 
                                         Text="{Binding ElementName=tv, Mode=OneWay, Path=SelectedItem.Header}"
                                         Template="{StaticResource ComboBoxTextBox}" 
                                         HorizontalAlignment="Left" 
                                         VerticalAlignment="Center" 
                                         Margin="3,3,23,3"
                                         Focusable="True" 
                                         Background="Transparent"
                                         Visibility="Hidden"
                                         IsReadOnly="{TemplateBinding IsReadOnly}"/>
                                <Popup Name="Popup"
                                       Placement="Bottom"
                                       IsOpen="{TemplateBinding IsDropDownOpen}"
                                       AllowsTransparency="True" 
                                       Focusable="False"
                                       PopupAnimation="Slide">
                                    <Grid Name="DropDown"
                                          SnapsToDevicePixels="True"                
                                          MinWidth="{TemplateBinding ActualWidth}"
                                          MaxHeight="{TemplateBinding MaxDropDownHeight}">
                                        <Border x:Name="DropDownBorder"
                                                Background="{StaticResource WindowBackgroundBrush}"
                                                BorderThickness="1"
                                                BorderBrush="{StaticResource SolidBorderBrush}">
                                            <ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True">
                                                <TreeView Name="tv">
                                                    <TreeViewItem Header="Employee1">
                                                        <TreeViewItem Header="Jesper"/>
                                                        <TreeViewItem Header="Aaberg"/>
                                                        <TreeViewItem Header="12345"/>
                                                    </TreeViewItem>
                                                    <TreeViewItem Header="Employee2">
                                                        <TreeViewItem Header="Dominik"/>
                                                        <TreeViewItem Header="Paiha"/>
                                                        <TreeViewItem Header="98765"/>
                                                    </TreeViewItem>
                                                </TreeView>
                                            </ScrollViewer>
                                        </Border>

                                    </Grid>
                                </Popup>
                            </Grid>
                            <ControlTemplate.Triggers>
                                <Trigger Property="HasItems" Value="false">
                                    <Setter TargetName="DropDownBorder" Property="MinHeight" Value="95"/>
                                </Trigger>
                                <Trigger Property="IsEnabled" Value="false">
                                    <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}"/>
                                </Trigger>
                                <Trigger Property="IsGrouping" Value="true">
                                    <Setter Property="ScrollViewer.CanContentScroll" Value="false"/>
                                </Trigger>
                                <Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="true">
                                    <Setter TargetName="DropDownBorder" Property="CornerRadius" Value="4"/>
                                    <Setter TargetName="DropDownBorder" Property="Margin" Value="0,2,0,0"/>
                                </Trigger>
                                <Trigger Property="IsEditable" Value="true">
                                    <Setter Property="IsTabStop" Value="false"/>
                                    <Setter TargetName="PART_EditableTextBox" Property="Visibility"    Value="Visible"/>
                                    <Setter TargetName="ContentSite" Property="Visibility" Value="Hidden"/>
                                </Trigger>
                            </ControlTemplate.Triggers>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>