WPF:可编辑的组合框掉落? [英] WPF: Editable ComboBox that drops up?

问题描述

我正在尝试创建一个既可编辑又可下拉而不是下拉的组合框.按向上箭头键(默认为向下)时，菜单也应该打开.

Im trying to create a ComboBox thats both editable and drops up instead of down. The menu should also open when pressing the up-arrow-key (down by default).

我尝试修改 ComboBox 的默认 ControlTemplate，但它似乎不支持 IsEditable?

I have tried modifying the default ControlTemplate for ComboBox but it doesn't seem to have any support for IsEditable?

推荐答案

默认的 ControlTemplate 不适用于 IsEditable = true 品种，但该样式包含一个触发器设置 IsEditable 时更改它:

The default ControlTemplate is not for the IsEditable = true variety, but the style contains a trigger that changes it when IsEditable is set:

<Style.Triggers>
    <Trigger Property="IsEditable" Value="true">
        <Setter Property="BorderBrush" Value="{StaticResource TextBoxBorder}"/>
        <Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
        <Setter Property="IsTabStop" Value="false"/>
        <Setter Property="Padding" Value="3"/>
        <Setter Property="Template" Value="{StaticResource ComboBoxEditableTemplate}"/>
    </Trigger>
</Style.Triggers>

它将其更改为另一个 ControlTemplate，其中相关部​​分是弹出窗口:

It changes it to another ControlTemplate where the relevant part is the popup:

<Popup x:Name="PART_Popup" 
       AllowsTransparency="true" 
       Grid.ColumnSpan="2" 
       IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" 
       Placement="Bottom">
...
</Popup>

我认为您应该能够将 Placement 属性更改为 Top.

I think you should just be able to change the Placement property to Top.

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