Get the the source from ToggleButton contained into a style

Question

I have multiple expanders using a style. Into the style is defined a toggle button, and when I click on It I need to detect which off the togglebutton have been clicked.

expander 1:

 <Expander Style="{StaticResource PreviewExpanderNewGeneration}" VerticalAlignment="Top"  Grid.ColumnSpan="2" Name="expander1"  OverridesDefaultStyle="True" Header="Expander1Header" Margin="0,0,0,0">
        <GroupBox   Height="150"  FontStyle="Normal" utilities:GroupNameUpperConverter.CharacterCasing="Upper" Name="ContainerforExpander1" Background="#717171"  Margin="0,0,0,0" >
        </GroupBox>
 </Expander>

expander 2:

<Expander Style="{StaticResource PreviewExpanderNewGeneration}" VerticalAlignment="Top"  Grid.ColumnSpan="2" Name="expander2"  OverridesDefaultStyle="True" Header="Expander2Header" Margin="0,0,0,0">
        <GroupBox   Height="150"  FontStyle="Normal" utilities:GroupNameUpperConverter.CharacterCasing="Upper" Name="ContainerforExpander2" Background="#717171"  Margin="0,0,0,0" >
        </GroupBox>
 </Expander>

the style define contains a Togglebutton who change graphically when clicked on. But I want to know which of the togglebutton from the expanders have been clicked: XAML

 <Style TargetType="Expander" x:Key="PreviewExpanderNewGeneration" BasedOn="{StaticResource BaseControlStyle}" >
            <!--x:Key="GroupBoxStyle"-->
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="Expander">
                        <Grid>
                            <!--Grid Rows split the GroupBox into two areas -->
                            <Grid.RowDefinitions>
                                <RowDefinition Height="30"/>
                                <RowDefinition Height="100"/>
                            </Grid.RowDefinitions>
                            <!--Header area-->
                            <Border Name="HeaderArea"
      Grid.Row="0"
      Background="Transparent"
     VerticalAlignment="Center"
      BorderBrush="Transparent"
      BorderThickness="1"
      CornerRadius="2,2,0,0" >
                                <Grid>
                                    <Grid.ColumnDefinitions>
                                        <ColumnDefinition Width="67"/>
                                        <ColumnDefinition Width="45"/>
                                        <ColumnDefinition Width="95"/>
                                        <ColumnDefinition Width="100"/>
                                    </Grid.ColumnDefinitions>
                                    <StackPanel Orientation="Horizontal" Grid.Column="0" Grid.ColumnSpan="3" >
                                        <Label Foreground="White" Grid.Column="0" utilities:LabelUpperCase.CharacterCasing="Upper"  Name="PreviewLabelExpander" FontSize="15"  HorizontalAlignment="Left" Loaded="PreviewLabelExpander_Loaded" FontWeight="Normal" Content="{TemplateBinding Header}" ></Label>

                                        <StackPanel VerticalAlignment="Center">
                                            <StackPanel.Style>
                                                <Style TargetType="StackPanel">
                                                    <Style.Triggers>
                                                        <DataTrigger  Binding="{Binding IsHelp}" Value="true">
                                                            <Setter Property="Visibility" Value="Visible"/>
                                                        </DataTrigger>
                                                        <DataTrigger Binding="{Binding IsHelp}" Value="false">
                                                            <Setter Property="Visibility" Value="Collapsed"/>
                                                        </DataTrigger>
                                                    </Style.Triggers>
                                                </Style>
                                            </StackPanel.Style>
                                            




                                        </StackPanel>
                                    </StackPanel>
                                    <ToggleButton                             
                                        
                                    Grid.Row="0"
                                    Grid.Column="3"
                                    Margin="79,4,0,4"  
                                    VerticalAlignment="Center" 
                                    HorizontalAlignment="Left"
                                    Template="{StaticResource PreviewToggleButton}"
                                    OverridesDefaultStyle="True"   
                                   Click="PreviewExpanderButton_Click"
                                       IsChecked="{Binding Path=IsExpanded, RelativeSource={RelativeSource TemplatedParent}}"
                                     Width="20">
                                 </ToggleButton>
                                </Grid>
                               



                            </Border>
                            <!-- Main client area -->
                            <Border Name="ContentArea"
     Grid.Row="1"
     Height="100"        
      BorderBrush="Transparent"
      BorderThickness="1,1,1,1"
      CornerRadius="6,5,6,6" >
                                <ContentPresenter x:Name="ExpanderContent"
                                                   
                                                  VerticalAlignment="Top"
                                                  Height="100"
                                                  Margin="0,0,0,0" >

                                    <ContentPresenter.LayoutTransform>
                                        <ScaleTransform ScaleY="0"></ScaleTransform>

                                    </ContentPresenter.LayoutTransform>
                                </ContentPresenter>
                            </Border>
                        </Grid>

                        <ControlTemplate.Triggers>
                            <Trigger Property="IsExpanded" Value="True">
                                <Trigger.EnterActions>
                                    <BeginStoryboard>
                                        <Storyboard>
                                            <DoubleAnimation Storyboard.TargetName="ExpanderContent"
                                             Storyboard.TargetProperty="(ContentPresenter.LayoutTransform).(ScaleTransform.ScaleY)"                                                 
                                             To="1"
                                             Duration="0:0:0.4"/>
                                        </Storyboard>
                                    </BeginStoryboard>
                                </Trigger.EnterActions>
                                <Trigger.ExitActions>
                                    <BeginStoryboard>
                                        <Storyboard>
                                            <DoubleAnimation Storyboard.TargetName="ExpanderContent"
                                             Storyboard.TargetProperty="(ContentPresenter.LayoutTransform).(ScaleTransform.ScaleY)"
                                             To="0"
                                             Duration="0:0:0.4"/>
                                        </Storyboard>
                                    </BeginStoryboard>
                                </Trigger.ExitActions>
                            </Trigger>

                        </ControlTemplate.Triggers>

                    </ControlTemplate>
                </Setter.Value>
            </Setter>


        </Style>

and now the click event should detect the source but how?

 private void PreviewExpanderButton_Click(object sender, RoutedEventArgs e)
    {

     //how to detect which of the toogle button have been clicked?
       ToggleButton tmp = (ToggleButton) sender;
        
              
    }

Answer 1

If you want to get a reference to the parent Expander of the ToggleButton that was clicked, you could use the following helper method:

private void PreviewExpanderButton_Click(object sender, RoutedEventArgs e)
{
    ToggleButton tmp = (ToggleButton)sender;
    Expander expander = FindParent<Expander>(tmp);

    MessageBox.Show(expander?.Name ?? String.Empty);
}

private static T FindParent<T>(DependencyObject dependencyObject) where T : DependencyObject
{
    var parent = VisualTreeHelper.GetParent(dependencyObject);

    if (parent == null) return null;

    var parentT = parent as T;
    return parentT ?? FindParent<T>(parent);
}