WPF：掉落的可编辑组合框？ [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ComboBox。按下向上箭头键（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，但似乎没有有对IsEditable的支持吗？

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 IsEditable = true 变体，但是样式包含一个触发器，当设置了IsEditable时，该触发器会对其进行更改：

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 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>

我认为您应该可以更改展示位置属性设置为顶部。

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

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