自定义组合框样式不显示选定项

Question

我正在设计一个ComboBox，我只是复制粘贴默认样式并已经更改了一些东西。
我遇到的问题是没有显示SelectedItem。

也许xaml大师可以帮助我找到错误。combobox将无法编辑，所以我想问题出在ContentSite，但我不太确定如何让它工作。

提前感谢！

编辑： 我已经检查过是否有SelectedItem，如果我使用普通的组合框，则会显示该项目。 当前样式：

<ControlTemplate x:Key="ToggleButton"
TargetType="{x:Type ToggleButton}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="50" />
</Grid.ColumnDefinitions>
<Border x:Name="Border"
Grid.ColumnSpan="2"
Background="{StaticResource ColorMagnoscoGreen}"
BorderBrush="#FF97A0A5"
BorderThickness="1"
CornerRadius="0" />
<Border Grid.Column="0"
Margin="1"
Background="White"
BorderThickness="1"
CornerRadius="0" />
<Path x:Name="Arrow"
Grid.Column="1"
HorizontalAlignment="Center"
VerticalAlignment="Center"
Data="M0,0 L0,2 L4,6 L8,2 L8,0 L4,4 z"
Fill="White" />
</Grid>
</ControlTemplate>
<ControlTemplate x:Key="ComboBoxTextBox"
TargetType="{x:Type TextBox}">
<Border x:Name="PART_ContentHost"
BorderThickness="1"
Focusable="False">
</Border>
</ControlTemplate>
<Style x:Key="{x:Type ComboBox}"
TargetType="{x:Type ComboBox}">
<Setter Property="SnapsToDevicePixels" Value="true" />
<Setter Property="OverridesDefaultStyle" Value="true" />
<Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto" />
<Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
<Setter Property="ScrollViewer.CanContentScroll" Value="true" />
<Setter Property="MinWidth" Value="120" />
<Setter Property="MinHeight" Value="40" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<ContentPresenter x:Name="ContentSite"
IsHitTestVisible="False"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
Margin="3,3,23,3"
VerticalAlignment="Stretch"
HorizontalAlignment="Left">
</ContentPresenter>
<TextBox x:Name="PART_EditableTextBox"
Style="{x:Null}"
Template="{StaticResource ComboBoxTextBox}"
HorizontalAlignment="Left"
VerticalAlignment="Bottom"
Margin="3,3,23,3"
Focusable="True"
Visibility="Hidden"
IsReadOnly="{TemplateBinding IsReadOnly}" />
<Popup Name="Popup"
AllowsTransparency="False"
Focusable="False"
IsOpen="{TemplateBinding IsDropDownOpen}"
Placement="Bottom"
PopupAnimation="Slide">
<Grid Name="DropDown"
Background="White"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}"
SnapsToDevicePixels="True">
<Border x:Name="DropDownBorder"
BorderBrush="#888888"
BorderThickness="1" />
<ScrollViewer Margin="4,6,4,6"
  SnapsToDevicePixels="True">
<StackPanel IsItemsHost="True"
      KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</Grid>
</Popup>
<ToggleButton Name="ToggleButton"
Grid.Column="2"
ClickMode="Press"
Focusable="false"
IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
Template="{StaticResource ComboBoxToggleButton}" />
</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="#888888" />
</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="0" />
<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>
<Style x:Key="{x:Type ComboBoxItem}"
TargetType="{x:Type ComboBoxItem}">
<Setter Property="SnapsToDevicePixels" Value="true" />
<Setter Property="Foreground" Value="Black" />
<Setter Property="OverridesDefaultStyle" Value="true" />
<Setter Property="FontSize" Value="16"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBoxItem}">
<Border Name="Border"
Padding="2"
SnapsToDevicePixels="true">
<ContentPresenter />
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsHighlighted" Value="true">
<Setter TargetName="Border" Property="Background" Value="{StaticResource ColorMagnoscoGreen}" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

Answer 1

ToggleButton

将ContentPresenter隐藏在ControlTemplate中。将ContentPresenter移到ToggleButton下方：

<Grid>
<TextBox x:Name="PART_EditableTextBox"
Style="{x:Null}"
Template="{StaticResource ComboBoxTextBox}"
HorizontalAlignment="Left"
VerticalAlignment="Bottom"
Margin="3,3,23,3"
Focusable="True"
Visibility="Hidden"
IsReadOnly="{TemplateBinding IsReadOnly}" />
<Popup Name="Popup"
AllowsTransparency="False"
Focusable="False"
IsOpen="{TemplateBinding IsDropDownOpen}"
Placement="Bottom"
PopupAnimation="Slide">
<Grid Name="DropDown"
Background="White"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}"
SnapsToDevicePixels="True">
<Border x:Name="DropDownBorder"
BorderBrush="#888888"
BorderThickness="1" />
<ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True">
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</Grid>
</Popup>
<ToggleButton Name="ToggleButton"
Grid.Column="2"
ClickMode="Press"
Focusable="false"
IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
Template="{StaticResource ComboBoxToggleButton}" />
<ContentPresenter x:Name="ContentSite"
IsHitTestVisible="False"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
Margin="3,3,23,3"
VerticalAlignment="Stretch"
HorizontalAlignment="Left">
</ContentPresenter>
</Grid>