列表框展开选定项

Question

列表框展开选定项

3

我有以下代码片段（复制并粘贴到kaxaml、xamlpad等中尝试），它可以折叠除所选项目外的所有内容。然而，当鼠标不在ListBox上时，我想恢复所有可见内容，但是我无法做到除了在代码后台进行。我正在使用IsMouseOver ListBox属性设置ListBox上所选项目的属性来尝试触发更新，但没有成功。有什么想法吗？

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
 <Grid>
      <ListBox
           Name="lb"
           Width="100"
           Height="100"
           Background="Red"
           SelectionMode="Single">
           <ListBox.ItemsPanel>
                <ItemsPanelTemplate>
                     <UniformGrid Columns="1"/>
                </ItemsPanelTemplate>
           </ListBox.ItemsPanel>
           <ListBoxItem Background="AliceBlue">项目 1    
           </ListBoxItem>
           <ListBoxItem Background="Aquamarine">项目 2  
           </ListBoxItem>
           <ListBoxItem Background="Azure">项目 3 
           </ListBoxItem>
           <ListBox.ItemContainerStyle>
                <Style TargetType="{x:Type ListBoxItem}">
                     <Setter Property="Visibility" Value="Visible"/>
                     <Style.Triggers>
                          <MultiDataTrigger>
                               <MultiDataTrigger.Conditions>
                                    <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="False"/>
                                    <Condition Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}},Path=SelectedItems.Count}" Value="1"/>
                               </MultiDataTrigger.Conditions>
                               <MultiDataTrigger.EnterActions>
                                    <BeginStoryboard>
                                         <Storyboard Duration="0:0:1">
                                              <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
                                                   <DiscreteObjectKeyFrame KeyTime="0:0:1" Value="{x:Static Visibility.Collapsed}"/>
                                              </ObjectAnimationUsingKeyFrames>
                                              <DoubleAnimation Duration="0:0:1" Storyboard.TargetProperty="Opacity" To="0"/>
                                         </Storyboard>
                                    </BeginStoryboard>
                               </MultiDataTrigger.EnterActions>
                          </MultiDataTrigger>
                          <MultiDataTrigger>
                               <MultiDataTrigger.Conditions>
                                    <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="True"/>
                                    <Condition Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}},Path=SelectedItems.Count}" Value="1"/>
                               </MultiDataTrigger.Conditions>
                               <MultiDataTrigger.EnterActions>
                                    <BeginStoryboard>
                                         <Storyboard Duration="0:0:0">
                                              <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
                                                   <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{x:Static Visibility.Visible}"/>
                                              </ObjectAnimationUsingKeyFrames>
                                              <DoubleAnimation Duration="0:0:0" Storyboard.TargetProperty="Opacity" To="1"/>
                                         </Storyboard>
                                    </BeginStoryboard>
                               </MultiDataTrigger.EnterActions>
                          </MultiDataTrigger>
                     </Style.Triggers>
                </Style>
           </ListBox.ItemContainerStyle>
           <ListBox.Style>
                <Style>
                     <Style.Triggers>
                          <Trigger Property="ListBox.IsMouseOver" Value="False">
                               <Setter Property="ListBox.SelectedItem" Value="{x:Null}"/>
                               <Setter Property="ListBoxItem.IsSelected" Value="False"/>
                               <Setter Property="ListBox.SelectedIndex" Value="-1"/>
                          </Trigger>
                          <EventTrigger RoutedEvent="Mouse.MouseLeave">
                               <BeginStoryboard>
                                    <Storyboard>
                                         <Int32Animation Duration="0:0:0" Storyboard.TargetProperty="SelectedIndex" To="-1"/>
                                    </Storyboard>
                               </BeginStoryboard>
                          </EventTrigger>
                     </Style.Triggers>
                </Style>
           &

- HiteshP

1个回答

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- Dmytro Laptin · Accepted Answer

将样式移至资源中，并在鼠标悬停在ListBox上时应用它。

<Page.Resources>
    <Style x:Key="CustomStyle" TargetType="{x:Type ListBoxItem}">
        <Style.Triggers>
            <MultiDataTrigger>
                <MultiDataTrigger.Conditions>
                    <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="False"/>
                    <Condition Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBox}},Path=SelectedItems.Count}" Value="1"/>
                </MultiDataTrigger.Conditions>
                <MultiDataTrigger.EnterActions>
                    <BeginStoryboard>
                        <Storyboard Duration="0:0:1">
                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
                                <DiscreteObjectKeyFrame KeyTime="0:0:1" Value="{x:Static Visibility.Collapsed}"/>
                            </ObjectAnimationUsingKeyFrames>
                            <DoubleAnimation Duration="0:0:1" Storyboard.TargetProperty="Opacity" To="0"/>
                        </Storyboard>
                    </BeginStoryboard>
                </MultiDataTrigger.EnterActions>
                <MultiDataTrigger.ExitActions>
                    <BeginStoryboard>
                        <Storyboard Duration="0:0:0">
                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">
                                <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{x:Static Visibility.Visible}"/>
                            </ObjectAnimationUsingKeyFrames>
                            <DoubleAnimation Duration="0:0:0" Storyboard.TargetProperty="Opacity" To="1"/>
                        </Storyboard>
                    </BeginStoryboard>
                </MultiDataTrigger.ExitActions>
            </MultiDataTrigger>
        </Style.Triggers>
    </Style>
</Page.Resources>

<Grid>
    <ListBox
       Name="lb"
       Width="100"
       Height="100"
       Background="Red"
       SelectionMode="Single">
        <ListBox.ItemsPanel>
            <ItemsPanelTemplate>
                <UniformGrid Columns="1"/>
            </ItemsPanelTemplate>
        </ListBox.ItemsPanel>
        <ListBoxItem Background="AliceBlue">Item 1
        </ListBoxItem>
        <ListBoxItem Background="Aquamarine">Item
        </ListBoxItem>
        <ListBoxItem Background="Azure">Item
        </ListBoxItem>
        <ListBox.Style>
            <Style>
                <Style.Triggers>
                    <Trigger Property="ListBox.IsMouseOver" Value="True">
                        <Setter 
                            Property="ListBox.ItemContainerStyle" 
                            Value="{StaticResource CustomStyle}"/>
                    </Trigger>
                </Style.Triggers>
            </Style>
        </ListBox.Style>
    </ListBox>
</Grid>

还要注意MultiDataTrigger.ExitActions的使用，这些是在触发对象变为非活动状态时应用的操作。