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我在主列表中有ListBox一个ListboxItem。在一个项目中，ListBox我选择了一个项目。当我从其他项目中选择了另一个项目时，应该清除此选择ListBox。代码如下：

<ListBox x:Name="lst" Grid.Row="3" BorderThickness="0" ScrollViewer.HorizontalScrollBarVisibility="Hidden" ItemsSource="{Binding MessageCollection}"  ScrollViewer.CanContentScroll="False" >
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Vertical"  Width="{Binding RelativeSource= {RelativeSource FindAncestor, AncestorType={x:Type Grid}},Path=ActualWidth}" HorizontalAlignment="Stretch">
                <Border  Background ="#ffffff" BorderBrush="#dddddd" BorderThickness="0,1,0,0" Height="30" >
                    <TextBlock Text="{Binding Date, StringFormat={}{0:dd MMMM yyyy}}" VerticalAlignment="Center" FontWeight="Bold" FontSize="12" FontFamily="Tahoma"  Foreground="#7a7a7a" HorizontalAlignment="Center" />
                </Border>

                    <ListBox x:Name="lstMsgs" HorizontalAlignment="Stretch" ScrollViewer.HorizontalScrollBarVisibility="Hidden"  HorizontalContentAlignment="Stretch"  ItemsSource="{Binding MessageList}" SelectedItem="{Binding DataContext.SelectedMessage,Mode=TwoWay,ElementName=me}" Background="Transparent" BorderThickness="0">
                        <ListBox.ItemTemplate>
                            <DataTemplate>
                                <Border x:Name="brdItem" BorderBrush="#dddddd" BorderThickness="0,1,0,0" >
                                    <Border.Background>
                                        <LinearGradientBrush  StartPoint="0,0" EndPoint="0,1">
                                            <GradientStop Color="#f1f1f1" Offset="0"/>
                                            <GradientStop Color="#efefef" Offset="1"/>
                                        </LinearGradientBrush>
                                    </Border.Background>

                                    <Grid Height="30" HorizontalAlignment="Stretch" VerticalAlignment="Center" ScrollViewer.HorizontalScrollBarVisibility="Hidden"  >
                                            <Grid.ColumnDefinitions>
                                                <ColumnDefinition Width="10" />
                                                <ColumnDefinition Width="30" />
                                                <ColumnDefinition Width="10" />
                                                <ColumnDefinition Width="120" />
                                                <ColumnDefinition Width="10" />
                                                <ColumnDefinition Width="*" />
                                                <ColumnDefinition Width="10" />
                                                <ColumnDefinition Width="100" />
                                                <ColumnDefinition Width="30" />
                                            </Grid.ColumnDefinitions>
                                            <Image x:Name="img" Grid.Column="1" Visibility="Collapsed"  HorizontalAlignment="Center" Source="Images\icon1.png" Stretch="None" Margin="10,0,0,0"  />
                                            <TextBlock Text="Ershad Sheikh" VerticalAlignment="Center" Foreground="#2b2a2a" FontSize="12" Grid.Column="3" />
                                            <TextBlock Text="{Binding GroupMessage}" HorizontalAlignment="Left" Foreground="#7a7a7a" FontSize="11"  Grid.Column="5" VerticalAlignment="Center" TextTrimming="CharacterEllipsis" />
                                            <TextBlock Text="{Binding Date, StringFormat={}{0: hh:mm:ss tt}}" FontWeight="Bold" FontSize="12" Foreground="#2378a0"  Grid.Column="7" VerticalAlignment="Center" HorizontalAlignment="Right" />
                                        </Grid>
                                    </Border>
                                    <DataTemplate.Triggers>
                                        <DataTrigger Binding="{Binding Path=IsReplyPresent}" Value="True">
                                            <Setter TargetName="img" Property="Visibility" Value="Visible" />
                                        </DataTrigger>
                                        <DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ListBoxItem}}, Path=IsSelected}" Value="True">
                                            <Setter TargetName="brdItem" Property="Background" Value="#e5e9eb" >                                                    
                                            </Setter>
                                        </DataTrigger>
                                    </DataTemplate.Triggers>
                                </DataTemplate>
                            </ListBox.ItemTemplate>

                            <ListBox.Resources>
                                <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" 
                     Color="#e5e9eb"/>
                                <SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" 
                     Color="Transparent" />
                                <SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}" Color="Black"/>
                            </ListBox.Resources>
                        </ListBox>
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
            <ListBox.Resources>
                <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" 
                       Color="#e5e9eb"/>
                <SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" 
                     Color="Transparent" />
            </ListBox.Resources>
        </ListBox>
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1 回答 1

1

您可以明确地null在失去焦点SelectedItem时ListBox，即您必须处理LostFocus事件。

您可以将事件处理程序添加到ListBox并在后面的代码中处理事件。

XAML 更改：

<ListBox x:Name="lstMsgs" HorizontalAlignment="Stretch" ScrollViewer.HorizontalScrollBarVisibility="Hidden"  HorizontalContentAlignment="Stretch"  ItemsSource="{Binding MessageList}" SelectedItem="{Binding DataContext.SelectedMessage,Mode=TwoWay,ElementName=me}" Background="Transparent" BorderThickness="0" LostFocus="lstMsgs_LostFocus">

代码背后：

    private void lstMsgs_LostFocus(object sender, RoutedEventArgs e)
    {
        ListBox listBox = sender as ListBox;
        if (listBox != null)
        {
            listBox.SelectedItem = null;
        }
    }

方法二：

您可以通过使用 aDependencyProperty来处理LostFocus事件来获得相同的结果。

列表框扩展.cs

using System.Windows;
using System.Windows.Controls;

namespace WpfApplication1
{
    public static class ListBoxExtension
    {
        public static readonly DependencyProperty NullSelectedItemOnLostFocusProperty =
            DependencyProperty.RegisterAttached("NullSelectedItemOnLostFocus", typeof(bool), typeof(ListBoxExtension), new UIPropertyMetadata(false, OnNullSelectedItemOnLostFocusChanged));

        public static bool GetNullSelectedItemOnLostFocus(DependencyObject d)
        {
            return (bool)d.GetValue(NullSelectedItemOnLostFocusProperty);
        }

        public static void SetNullSelectedItemOnLostFocus(DependencyObject d, bool value)
        {
            d.SetValue(NullSelectedItemOnLostFocusProperty, value);
        }

        private static void OnNullSelectedItemOnLostFocusChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            bool nullSelectedItemOnLostFocus = (bool)e.NewValue;

            ListBox listBox = d as ListBox;
            if (listBox != null)
            {
                if (nullSelectedItemOnLostFocus)
                    listBox.LostFocus += NullSelectedItem;
                else
                    listBox.LostFocus -= NullSelectedItem;
            }
        }

        public static void NullSelectedItem(object sender, RoutedEventArgs e)
        {
            ListBox listBox = sender as ListBox;
            if (listBox != null)
            {
                listBox.SelectedItem = null;
            }
        }
    }
}

XAML 更改 1：添加 ListBoxExtension 类所在的命名空间 - xmlns:loc="clr-namespace:WpfApplication1"

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:loc="clr-namespace:WpfApplication1"
        Title="MainWindow" Height="350" Width="525">

XAML 更改 2：更改DependencyProperty- loc:ListBoxExtension.NullSelectedItemOnLostFocus="True"

<ListBox x:Name="lstMsgs" HorizontalAlignment="Stretch" ScrollViewer.HorizontalScrollBarVisibility="Hidden"  HorizontalContentAlignment="Stretch"  ItemsSource="{Binding MessageList}" SelectedItem="{Binding DataContext.SelectedMessage,Mode=TwoWay,ElementName=me}" Background="Transparent" BorderThickness="0" loc:ListBoxExtension.NullSelectedItemOnLostFocus="True">
于 2013-07-26T12:35:55.627 回答