【发布时间】：2019-01-25 09:37:42
【问题描述】：
我有一个组合框，它使用一种样式来允许使用列表框进行多项选择（如果需要，问题底部的完整样式）。控件绑定到ObservableCollection<Foo>； Foo 有点像这样：
public class Foo
{
ComplexOtherClass Complex { get; set; }
string Label { get; set; }
}
样式中列表框的绑定如下所示：
<....
<ListBox x:Name="lstBox"
ItemsSource="{TemplateBinding ItemsSource}"
DisplayMemberPath="Label">
</ListBox>
..../>
这给了我一个很好的正确显示的字符串标签集合。问题是组合框顶部的控件模板不“知道”显示每个SelectedItems 的标签，因此它只显示每个选定项目的命名空间和类。
<ItemsControl x:Name="showMe"
ItemsSource="{Binding SelectedItems, ElementName=lstBox}">
</ItemsControl>
如何更改样式以使 ItemsControl 显示所选项目的 Label 属性？
我在 Google 上没有找到任何可以帮助我的东西 - 任何涉及多选组合框的搜索似乎都只是展示了如何制作一个，而没有解决这个特定问题！
这是完整的样式（抱歉所有静态资源，但希望结构仍然足够有意义以有用）
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="Brushes_Colours_rsrc.xaml"/>
</ResourceDictionary.MergedDictionaries>
<ControlTemplate x:Key="ComboBoxToggleButton" TargetType="{x:Type ToggleButton}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="20" />
</Grid.ColumnDefinitions>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="MouseOver">
<Storyboard>
<ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Panel.Background).(GradientBrush.GradientStops)[1].(GradientStop.Color)"
Storyboard.TargetName="Border">
<EasingColorKeyFrame KeyTime="0"
Value="{StaticResource ControlMouseOverColor}" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed" />
<VisualState x:Name="Disabled">
<Storyboard>
<ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Panel.Background).(GradientBrush.GradientStops)[1].(GradientStop.Color)"
Storyboard.TargetName="Border">
<EasingColorKeyFrame KeyTime="0"
Value="{StaticResource GlyphColor}" />
</ColorAnimationUsingKeyFrames>
<ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Shape.Fill).(SolidColorBrush.Color)"
Storyboard.TargetName="Arrow">
<EasingColorKeyFrame KeyTime="0"
Value="{StaticResource DisabledForegroundColor}" />
</ColorAnimationUsingKeyFrames>
<ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Border.BorderBrush).(GradientBrush.GradientStops)[1].(GradientStop.Color)"
Storyboard.TargetName="Border">
<EasingColorKeyFrame KeyTime="0"
Value="{StaticResource DisabledBorderDarkColor}" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="CheckStates">
<VisualState x:Name="Checked">
<Storyboard>
<ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Panel.Background).(GradientBrush.GradientStops)[1].(GradientStop.Color)"
Storyboard.TargetName="Border">
<EasingColorKeyFrame KeyTime="0"
Value="{StaticResource ControlPressedColor}" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Unchecked" />
<VisualState x:Name="Indeterminate" />
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="Border"
Grid.ColumnSpan="2"
CornerRadius="2"
BorderThickness="1">
<Border.BorderBrush>
<LinearGradientBrush EndPoint="0,1"
StartPoint="0,0">
<GradientStop Color="{DynamicResource BorderLightColor}"
Offset="0" />
<GradientStop Color="{DynamicResource BorderDarkColor}"
Offset="1" />
</LinearGradientBrush>
</Border.BorderBrush>
<Border.Background>
<LinearGradientBrush StartPoint="0,0"
EndPoint="0,1">
<!--button fill-->
<LinearGradientBrush.GradientStops>
<GradientStopCollection>
<GradientStop Color="{DynamicResource ControlLightColor}" />
<GradientStop Color="{DynamicResource ControlMediumColor}"
Offset="1.0" />
</GradientStopCollection>
</LinearGradientBrush.GradientStops>
</LinearGradientBrush>
</Border.Background>
</Border>
<Border Grid.Column="0"
CornerRadius="2,0,0,2"
Margin="1" >
<Border.Background>
<SolidColorBrush Color="{DynamicResource ControlLightColor}"/>
</Border.Background>
</Border>
<Path x:Name="Arrow"
Grid.Column="1"
HorizontalAlignment="Center"
VerticalAlignment="Center"
Data="M 0 0 L 4 4 L 8 0 Z" >
<Path.Fill>
<SolidColorBrush Color="Green"/>
</Path.Fill>
</Path>
</Grid>
</ControlTemplate>
<ControlTemplate x:Key="ComboBoxTextBox"
TargetType="{x:Type TextBox}">
<Border x:Name="PART_ContentHost"
Focusable="False"
Background="Green" />
</ControlTemplate>
<Style x:Key="MyMultiComboBox" 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="20" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="MouseOver" />
<VisualState x:Name="Disabled">
<Storyboard>
<ColorAnimationUsingKeyFrames Storyboard.TargetName="PART_EditableTextBox"
Storyboard.TargetProperty="(TextElement.Foreground).(SolidColorBrush.Color)">
<EasingColorKeyFrame KeyTime="0" Value="{StaticResource DisabledForegroundColor}" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="EditStates">
<VisualState x:Name="Editable">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="PART_EditableTextBox">
<DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Visible}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="ContentSite">
<DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Uneditable" />
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<ToggleButton x:Name="ToggleButton"
Template="{StaticResource ComboBoxToggleButton}"
Grid.Column="2"
Focusable="false"
ClickMode="Press"
IsChecked="{Binding IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"/>
<ItemsControl x:Name="showMe" IsHitTestVisible="false" Style="{StaticResource Text_NormalText}" ItemsSource="{Binding SelectedItems, ElementName=lstBox}" Margin="1,0,22,0">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel IsItemsHost="True" Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
<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"
Background="Transparent"
Visibility="Hidden"
IsReadOnly="{TemplateBinding IsReadOnly}" />
<Popup x:Name="Popup"
Placement="Bottom"
IsOpen="{TemplateBinding IsDropDownOpen}"
AllowsTransparency="True"
Focusable="False"
PopupAnimation="Slide">
<Grid x:Name="DropDown"
SnapsToDevicePixels="True"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder" BorderThickness="1">
<Border.BorderBrush>
<SolidColorBrush Color="{DynamicResource BorderMediumColor}" />
</Border.BorderBrush>
<Border.Background>
<SolidColorBrush Color="{DynamicResource ControlLightColor}" />
</Border.Background>
</Border>
<ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True">
<!--<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />-->
<ListBox x:Name="lstBox"
Background="{StaticResource DarkGreenBackground}"
Style="{StaticResource Text_NormalText}"
TextBlock.FontSize="12"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"
KeyboardNavigation.DirectionalNavigation="Contained" SelectionMode="Multiple"
ItemsSource="{TemplateBinding ItemsSource}"
DisplayMemberPath="Label"
>
</ListBox>
</ScrollViewer>
</Grid>
</Popup>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="HasItems" Value="false">
<Setter TargetName="DropDownBorder" Property="MinHeight" Value="95" />
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false" />
</Trigger>
<Trigger SourceName="Popup" Property="AllowsTransparency" Value="true">
<Setter TargetName="DropDownBorder" Property="CornerRadius" Value="4" />
<Setter TargetName="DropDownBorder" Property="Margin" Value="0,2,0,0" />
</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="OverridesDefaultStyle" Value="true" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBoxItem}">
<Border x:Name="Border"
Padding="2"
SnapsToDevicePixels="true"
Background="Transparent">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="SelectionStates">
<VisualState x:Name="Unselected" />
<VisualState x:Name="Selected">
<Storyboard>
<ColorAnimationUsingKeyFrames Storyboard.TargetName="Border" Storyboard.TargetProperty="(Panel.Background).(SolidColorBrush.Color)">
<EasingColorKeyFrame KeyTime="0" Value="{StaticResource Good}" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="SelectedUnfocused">
<Storyboard>
<ColorAnimationUsingKeyFrames Storyboard.TargetName="Border" Storyboard.TargetProperty="(Panel.Background).(SolidColorBrush.Color)">
<EasingColorKeyFrame KeyTime="0" Value="{StaticResource SelectedUnfocusedColor}" />
</ColorAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<ContentPresenter />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>
编辑 尝试绑定文本块而不是 ItemsControl 失败 - 文本块中未显示任何内容。
<Style.Resources>
<base:CollectionToStringConverter x:Key="ToList"/>
</Style.Resources>
...和...
<....
<TextBlock x:Name="showMe" IsHitTestVisible="False"
TextTrimming="CharacterEllipsis"
Background="HotPink" Foreground="Black"
DataContext="{Binding SelectedItems,ElementName=lstBox}"
Text="{Binding SelectedItem.Label,Converter={StaticResource ToList}}"
Margin="1,1,22,1">
</TextBlock>
....>
【问题讨论】：
-
应该是
Text="{Binding SelectedItems, ElementName=lstBox, Converter={StaticResource ToList}}"并删除DataContext。转换器应返回所有标签的字符串连接。