wpf - 无法清除 WPF ListBox.SelectedItems 集合

Question

我似乎无法清除数据绑定(bind) WPF ListBox 的 SelectedItems 集合。我尝试调用 ListBox.SelectedItems.Clear()，尝试将 SelectedIndex 设置为 -1，将 SelectedItem 设置为 null 并调用 ListBox.UnselectAll()。在调试时，似乎要么没有分配任务，要么正在重置 SelectedItems 集合，但我不确定是什么。我在 SelectionChanged 回调中放置了一个断点，它永远不会被意外击中，但 SelectedItems.Count 成员始终至少为 1(有时大于 1，因为此 ListBox 的选择模式是 MultiExtended)。

有没有人见过这个并且知道我做错了什么？这个问题似乎与这个问题完全相同:
WPF - How to clear selection from ListView?

除了在那篇文章中，Sonny Boy 使用的是 ListView，而我使用的是 ListBox。无论如何，投票的答案是调用 ListView.UnselectAll() 这在我的情况下不起作用。

我觉得我必须做一些非常明显错误的事情，因为清除选择应该非常简单。

注意:为了清楚起见，我不想从 ListBox 中删除选择，我只想不选择任何内容。

谢谢!

                            <ListBox Background="{StaticResource ResourceKey=DarkGray}" Name="lbx_subimageThumbnails" Margin="6,6,6,0" ItemsSource="{Binding ElementName=lbx_thumbnails, Path=SelectedItem.Swatches}" Style="{StaticResource WPTemplate}" SelectionMode="Extended" Height="{Binding ElementName=sld_swatchRows, Path=Value}" VerticalAlignment="Top" SelectionChanged="lbx_subimageThumbnails_SelectionChanged" DataContext="{Binding}">
                            <ListBox.ItemsPanel>
                                <ItemsPanelTemplate>
                                    <WrapPanel HorizontalAlignment="Stretch" />
                                </ItemsPanelTemplate>
                            </ListBox.ItemsPanel>
                            <ListBox.ItemContainerStyle>
                                <Style TargetType="{x:Type ListBoxItem}">
                                    <Setter Property="Visibility" Value="{Binding Path=Vis}" />
                                </Style>
                            </ListBox.ItemContainerStyle>
                            <ListBox.ItemTemplate>
                                <DataTemplate>
                                    <Grid Width="270" Height="270" Margin="5,5,5,5" Tag="{Binding}" Name="lbx_swatchThumbnail" Background="{StaticResource ResourceKey=LightGray}" PreviewMouseLeftButtonDown="lbx_swatchThumbnail_PreviewMouseLeftButtonDown" PreviewMouseMove="lbx_swatchThumbnail_PreviewMouseMove">
                                        <Grid.LayoutTransform>
                                            <ScaleTransform CenterX="0" CenterY="0" ScaleX="0.50" ScaleY="0.50" />
                                        </Grid.LayoutTransform>
                                        <Grid.ContextMenu>
                                            <ContextMenu>
                                                <MenuItem Header="Sync selected" Click="btn_syncSwatch_Click" />
                                                <MenuItem Header="Re-export selected" Click="btn_exportSelected_Click"/>
                                                <MenuItem Header="Set as default thumbnail" Click="btn_setThumbnail_Click"/>
                                                <MenuItem Header="Delete selected" Click="btn_deleteSwatch_Click"/>
                                                <MenuItem Header="Show in Explorer" Click="mnu_showSwatchesInExplorer_Click" />
                                                <MenuItem Header="Create Frames" Click="mnu_createFrames_Click" ToolTip="Creates FRAMEs groups to your PSD file under the Group associated with the selected swatch. DO NOT RE-ORDER OR RENAME THE GENERATED groups!" />
                                                <MenuItem Header="Create MIPs" Click="mnu_createMIPs_Click" ToolTip="Creates MIPs groups to your PSD file under the Group associated with the selected swatch. DO NOT RE-ORDER OR RENAME THE GENERATED groups!" />
                                            </ContextMenu>
                                        </Grid.ContextMenu>
                                        <Border BorderBrush="Black" BorderThickness="1">
                                            <Grid ToolTip="{Binding Path=Texture}">
                                                <Image VerticalAlignment="Center" HorizontalAlignment="Center" PhotoLoader:Loader.DisplayOption="Preview" PhotoLoader:Loader.DisplayWaitingAnimationDuringLoading="True" PhotoLoader:Loader.Source="{Binding Path=Texture}" PhotoLoader:Loader.DisplayErrorThumbnailOnError="True" Width="256" Height="256" />
                                                <TextBlock VerticalAlignment="Top" HorizontalAlignment="Center" Margin="0,10,0,0" FontSize="20"  Text="{Binding Path=Group}" Background="Black" Foreground="White"/>
                                                <TextBlock VerticalAlignment="Bottom"  HorizontalAlignment="Center" Background="Black" Margin="0,0,0,10" FontSize="20" Foreground="White">
                                                    <TextBlock.Text>
                                                        <MultiBinding StringFormat="{}{0} x {1} {2}" >
                                                            <Binding Path="Width" />
                                                            <Binding Path="Height" />
                                                            <Binding Path="Format" />
                                                        </MultiBinding>
                                                    </TextBlock.Text>
                                                </TextBlock>
                                            </Grid>
                                        </Border>
                                    </Grid>
                                </DataTemplate>
                            </ListBox.ItemTemplate>
                        </ListBox>

        // this callback kicks everything off. 
        private void btn_editSwatch_Click(object sender, RoutedEventArgs e)
        {
            // get a list of the selected indices - we will have to unselect the texture source and reselect it after the re-export in order to force the thumbnail display to update
            // so we will save a list of indices to reselect them after the export
            List selectedIndices = new List();
            for (int i = 0; i < lbx_subimageThumbnails.Items.Count; i++)
            {
                if (lbx_subimageThumbnails.SelectedItems.Contains(lbx_subimageThumbnails.Items[i]))
                {
                    selectedIndices.Add(i);
                }
            }


        // store the index of the selected texture source to reselect it after the re-export
        int selIndex = lbx_thumbnails.SelectedIndex;

        // edit and re-export the selected thumbnails
        if (this.EditThumbnails(lbx_subimageThumbnails.SelectedItems, lbx_thumbnails.SelectedItem))
        {

            // re-select the texture source
            lbx_thumbnails.SelectedIndex = selIndex;

            // re-select the previously selected thumbnails.
            foreach (int index in selectedIndices)
            {
                if (!lbx_subimageThumbnails.SelectedItems.Contains(lbx_subimageThumbnails.Items[index]))
                {
                    lbx_subimageThumbnails.SelectedItems.Add(lbx_subimageThumbnails.Items[index]);
                }
            }
        }
    }

    private void lbx_subimageThumbnails_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        ListBox textureSelector = sender as ListBox;
        if (textureSelector != null)
        {
            //update some UI elements
        }
    }

    /*
    this is the SelectionChanged callback for another listbox which is bound as the ItemSource of lbx_subimageThumbnails. When the selection here changes, we default the selection of the subimage listbox to the first subimage after first clearing the selected items in the subimage listbox
    */
    private void lbx_thumbnails_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        // clear the previous swatch selection and select the first thumbnail
        // None of these methods works. after each, lbx_subimageThumbnails.SelectedItems.Count is still >= 1
        // Also, trying to set the SelectedIndex doesn't take. After the assignment, debugger shows                          
        // SelectedIndex is still 0 
        lbx_subimageThumbnails.SelectedIndex = -1;
        lbx_subimageThumbnails.SelectedIndex = -1;

        // Trying to set SelectedItem to null doesn't work...after assignment, SelectedItem is still a vaild
        // reference
        this.lbx_subimageThumbnails.SelectedItem = null;
        if (lbx_subimageThumbnails.SelectedItems.Count > 0)
        {
            lbx_subimageThumbnails.UnselectAll();
            lbx_subimageThumbnails.SelectedItems.Clear();
        }

        lbx_subimageThumbnails.SelectedIndex = 0;

        // reset the preview pane size
        sld_previewSize.Value = 1.0;
    }
			            

Answer 1

你是否覆盖了Equals()和 GetHashCode()在 ListBox 中的项目上？我可以通过以下方式复制它:

选择列表中的项目。

更改项目的属性会导致其哈希码发生更改。

选择不同的项目。

第一项未从 SelectedItems 中删除并且不能按照您描述的方式手动删除。即使 SelectionMode是单一的，如果您重新选择第一项，将导致抛出异常。