唯一的方法是为 ComboBox 定义一个新的 ControlTemplate。我在下面创建了一个样式,它将为您提供所需的功能。
<Style x:Key="ComboBoxStyle" TargetType="{x:Type ComboBox}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition MaxWidth="18"/>
</Grid.ColumnDefinitions>
<TextBox Name="PART_EditableTextBox"
Padding="5,0,0,0"
Background="Azure"
Height="{TemplateBinding Height}"
IsEnabled="{TemplateBinding IsEditable}"/>
<ToggleButton Grid.Column="1" Margin="0"
Height="{TemplateBinding Height}"
Focusable="False"
IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
ClickMode="Press">
<Path Grid.Column="1"
HorizontalAlignment="Center"
VerticalAlignment="Center"
Data="M 0 0 L 4 4 L 8 0 Z"
Fill="DodgerBlue" />
</ToggleButton>
<ContentPresenter Name="ContentSite"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
VerticalAlignment="Center"
HorizontalAlignment="Left"
Visibility="Visible"
Margin="5,0,0,0"/>
<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="Azure"
BorderThickness="1"
BorderBrush="Azure"/>
<ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True">
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</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="Gray"/>
</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>
您将需要修改颜色、边距等以满足您的需要,但它应该为您提供一个良好的起点。