Listbox SelectionChanged not working with Button i

问题:

Code below does not work when I select item in listbox, do you happen to know why?

<ListBox BorderBrush="Transparent" Background="Transparent" Name="listbox" HorizontalAlignment="Center" VerticalAlignment="Center" ScrollViewer.HorizontalScrollBarVisibility="Disabled" SelectionChanged="selection_changed">
    <ListBox.ItemsPanel>
        <ItemsPanelTemplate>
            <WrapPanel/>
        </ItemsPanelTemplate>
    </ListBox.ItemsPanel>
    <ListBox.ItemTemplate>
        <DataTemplate> 
            <Button Height="90" Width="150" Template="{StaticResource cbutton}"/>                
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox> 

And template cbutton looks like this

 <ControlTemplate x:Key="cbutton" TargetType="Button">
            <Border CornerRadius="3" BorderThickness="3.5" BorderBrush="White">
                <Border.Background>
                    <LinearGradientBrush EndPoint="1,1" StartPoint="0,0">
                        <GradientStop Color="DarkOrange" Offset="0.1"/>
                        <GradientStop Color="Orange" Offset="0.85"/>
                    </LinearGradientBrush>
                </Border.Background>
                <TextBlock FontWeight="ExtraBold" Foreground="White" TextAlignment="Center" TextWrapping="Wrap" FontSize="15" Text="{Binding name}" VerticalAlignment="Center" HorizontalAlignment="Center"/>
            </Border>
        </ControlTemplate>

回答1:

The SelectionChanged event is not fired because the button is the control who captures the mouse click, not the ListBox.

You can set your event handler to the button's click event instead.

   <Button Height="90" Width="150" Click="myClickEventHandler"/>  

Regardless, I recommend you to use MVVM, instead of Code-Behind event handler.

you could set a command which will fire when the button's click and send the command the button's content for example

  <Button Name="myButton" Height="90" Width="150" Template="{StaticResource cbutton}">     
      <i:Interaction.Triggers>
             <i:EventTrigger EventName="SelectionChanged">
                   <i:InvokeCommandAction Command="{Binding DoSomething}"  CommandParameter="{Binding ElementName=myButton, Path=Content}"/>
            </i:EventTrigger>
      </i:Interaction.Triggers>
  </Button>

ViewModel

DoSomething = new DelegateCommand<object>(content=> 
{
    // Do whatever you want 

});

If your not familar with MVVM, it will take some time to learn it, but it is definetly worth it :)

回答2:

You can add the PreviewMouseDown event handler on the ListBoxItem:

    <ListBox ItemsSource="{Binding ListBoxItemsSource}">
        <ListBox.ItemTemplate>
            <DataTemplate>
                <Button Content="{Binding}" />
            </DataTemplate>
        </ListBox.ItemTemplate>
        <ListBox.ItemContainerStyle>
            <Style TargetType="{x:Type ListBoxItem}">
                <EventSetter Event="PreviewMouseDown"
                             Handler="ItemOnPreviewMouseDown" />
            </Style>
        </ListBox.ItemContainerStyle>
    </ListBox>


    private void ItemOnPreviewMouseDown(
        object sender, MouseButtonEventArgs e)
    {
        ((ListBoxItem) sender).IsSelected = true;
    }