从列表框中获取所有选定的项目

Question

How Do you get the selected items from a listbox with checkboxes?

MainWindow.xaml

        <ListBox Margin="15" Name="MyListBox" 
             VerticalAlignment="Stretch"
             ItemsSource="{Binding Items}" 
             SelectionMode="Multiple" IsSynchronizedWithCurrentItem="True">
                <ListBox.Resources>
                    <Style TargetType="ListBoxItem">
                        <Setter Property="OverridesDefaultStyle" Value="true" />
                        <Setter Property="SnapsToDevicePixels" Value="true" />
                        <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="ListBoxItem">
                                    <CheckBox Margin="5,2" 
                                      IsChecked="{TemplateBinding IsSelected}">
                                        <ContentPresenter />
                                    </CheckBox>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Style>
                </ListBox.Resources>
            </ListBox>

My ItemsSource is an observable collection that gets some items added to it.

MainWindow.xaml.cs

public ObservableCollection<string> Items = new ObservableCollection<string>()
{"AAAAA", "BBBBB", "CCCCC", "DDDDD"};

DataContext = DataContext;
MyListBox.ItemsSource = Items;

This shows the items fine, but if I, in my interface then tries to select a couple of the items and get the selected items, I only ever get the first one. Why?

MyListBox.SelectedItems == "AAAA";

Answer 1

The CheckBox.IsChecked Binding needs to be TwoWay , which is not supported by TemplateBinding. Use a regular Binding instead (which is TwoWay by default here):

<CheckBox IsChecked="{Binding IsSelected,
                      RelativeSource={RelativeSource TemplatedParent}}" ...>
    <ContentPresenter />
</CheckBox>