WPF自定义ComboBox

<ControlTemplate x:Key="ComboBoxTextBox" TargetType="{x:Type TextBox}">
<Border x:Name="PART_ContentHost" Focusable="False" Background="{TemplateBinding Background}" />
</ControlTemplate>
<ControlTemplate x:Key="ComboBoxToggleButton" TargetType="{x:Type ToggleButton}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding XPath=bord}"/>
</Grid.ColumnDefinitions>
<Border x:Name="bord" Grid.Column="0" BorderThickness="2" BorderBrush="#e8e8e8" CornerRadius="5,5,5,5"/>
<Border Grid.Column="1" Background="#e8e8e8" Cursor="Hand" CornerRadius="5,5,5,5"/>
<Path x:Name="Arrow" Grid.Column="1" HorizontalAlignment="Center" VerticalAlignment="Center" Data="M 0 0 L 4 4 L 8 0 Z" Stretch="Fill" Fill="#e8e8e8"/>
</Grid>
</ControlTemplate>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<!-- ToggleButton 已数据绑定到 ComboBox 本身以切换 IsDropDownOpen -->
<ToggleButton Grid.Column="2" Template="{DynamicResource ComboBoxToggleButton}" x:Name="ToggleButton" Focusable="false" 
IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press"/>
<ContentPresenter HorizontalAlignment="Left" Margin="5,0,0,0" x:Name="ContentSite" VerticalAlignment="Center"
Content="{TemplateBinding SelectionBoxItem}" 
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
IsHitTestVisible="False"/>
<!-- 必须将 TextBox 命名为 PART_EditableTextBox，否则 ComboBox 将无法识别它 -->
<TextBox Visibility="Hidden" Template="{DynamicResource ComboBoxTextBox}" 
HorizontalAlignment="Left" x:Name="PART_EditableTextBox" Style="{x:Null}"
VerticalAlignment="Center" Focusable="True" Background="Transparent" Foreground="#2259AA" IsReadOnly="{TemplateBinding IsReadOnly}"/>
<!-- Popup 可显示 ComboBox 中的项列表。IsOpen 已数据绑定到通过 ComboBoxToggleButton 来切换的 IsDropDownOpen -->
<Popup IsOpen="{TemplateBinding IsDropDownOpen}" Placement="Bottom" x:Name="Popup" Focusable="False" AllowsTransparency="True" PopupAnimation="Slide">
<Grid MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{TemplateBinding ActualWidth}" x:Name="DropDown" SnapsToDevicePixels="True">
<Border x:Name="DropDownBorder" Background="{DynamicResource WindowBackgroundBrush}"
BorderBrush="{DynamicResource SolidBorderBrush}" BorderThickness="1"/>
<ScrollViewer Style="{DynamicResource SimpleScrollViewer}" SnapsToDevicePixels="True" HorizontalScrollBarVisibility="Auto"
VerticalScrollBarVisibility="Auto" CanContentScroll="True">
<!-- StackPanel 用于显示子级，方法是将 IsItemsHost 设置为 True -->
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" Background="White"/>
</ScrollViewer>
</Grid>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>