在子对象的情况下，如何更改父控件的属性？

Question

<Style TargetType="controls:ModernVerticalMenu" >
<Setter Property="FocusVisualStyle" Value="{x:Null}"/>
<Setter Property="Template">
    <Setter.Value>
        <ControlTemplate  TargetType="controls:ModernVerticalMenu">
            <Grid>
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="{TemplateBinding ListWidth}"/>
                                <ColumnDefinition Width="{TemplateBinding ListWidth}"/>
                                <ColumnDefinition Width="auto"/>
                                <ColumnDefinition />
                            </Grid.ColumnDefinitions>


                            <Border Background="{DynamicResource background}" Height="{TemplateBinding Height}" BorderThickness="1" BorderBrush="{DynamicResource bordaSuperior}">
                                <!-- link list -->
                                <ListBox x:Name="LinkList" ItemsSource="{TemplateBinding Links}"  
                                         ScrollViewer.HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}" >
                                    <ListBox.ItemTemplate>
                                        <DataTemplate>
                                            <Grid Height="50" Background="Transparent" Width="500">
                                                <Border Padding="10">
                                                    <Path x:Name="icon" Data="{Binding IconData}" Stretch="Fill" Fill="{DynamicResource Accent}" Width="20" Height="20" HorizontalAlignment="Left" VerticalAlignment="Center" />
                                                </Border>
                                                <TextBlock x:Name="texto" ToolTip="{Binding Tooltip}"  Text="{Binding DisplayName}" Margin="45,2,2,2" FontSize="{DynamicResource MediumFontSize}" TextTrimming="CharacterEllipsis" VerticalAlignment="Center" HorizontalAlignment="Left" />
                                            </Grid>
                                            <DataTemplate.Triggers>
                                                <DataTrigger Binding="{Binding IconData}" Value="{x:Null}">
                                                    <Setter Property="Margin" TargetName="texto">
                                                        <Setter.Value>
                                                            <Thickness Bottom="2" Top="2" Left="10" Right="2"/> 
                                                        </Setter.Value>
                                                    </Setter>
                                                </DataTrigger>
                                                <Trigger Property="IsMouseOver" Value="true">
                                                    <Setter Property="Fill" TargetName="icon">
                                                        <Setter.Value>
                                                            <SolidColorBrush Color="#f2f2f2" />
                                                        </Setter.Value>
                                                    </Setter>
                                                </Trigger>

                                            </DataTemplate.Triggers>
                                        </DataTemplate>
                                    </ListBox.ItemTemplate>
                                </ListBox>
                            </Border>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
     </Setter>
</Style>

I created a custom control and I am creating a template for a vertical menu, I wanna that in the event of MouseOver of the ListBox, I could set the value of proprierty of the controls:ModernVerticalMenu, any idea?

When I write parent, is the ModerVerticalMenu and child is the ListBox from the ControlTemplate.

Answer 1

The main idea is to somehow get access to parent object and change its property. In order to do this I create one attached property retrieving access to parent by TemplatedParent markup, second attached property stores value which is supposed to be applied in parent's property. This sample is not precise your problem but on the right track, I believe. I want to change button Content, which is initially Empty. First textblock reflects change in Button's Content to find out whether any occured.

<StackPanel>
    <TextBlock Text="{Binding ElementName=but, Path=Content}"/>
    <Button Name="but" Content="" Background="CadetBlue" BorderBrush="CadetBlue" BorderThickness="2">
        <Button.Template>
            <ControlTemplate TargetType="Button">
                <TextBox Margin="50" Text="xD" local:MyClass.Parent="{Binding RelativeSource={RelativeSource AncestorType=Button}}">
                    <TextBox.Style>
                        <Style TargetType="TextBox">
                            <Setter Property="local:MyClass.Content" Value="{x:Null}"/>
                            <Style.Triggers>
                                <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsMouseOver}" Value="True">
                                    <Setter Property="Foreground" Value="CadetBlue"/>
                                    <Setter Property="local:MyClass.Content" Value="tekst"/>
                                </DataTrigger>
                            </Style.Triggers>
                        </Style>
                    </TextBox.Style>
                </TextBox>
            </ControlTemplate>
        </Button.Template>
    </Button>
</StackPanel>

Class with attached properties looks as follows

public static class MyClass
{
    public static void SetParent(DependencyObject obj, Button val)
    {
        obj.SetValue(ParentProperty, val);
    }

    public static Button GetParent(DependencyObject obj)
    {
        return (Button)obj.GetValue(ParentProperty);
    }
    public static readonly DependencyProperty ParentProperty = DependencyProperty.RegisterAttached("Parent", typeof(Button), typeof(MyClass), new PropertyMetadata(null, new PropertyChangedCallback(
        (x, y) =>
        {
            Debug.WriteLine(GetParent(x));
        })));

    public static void SetContent(DependencyObject obj, string val)
    {
        obj.SetValue(ContentProperty, val);
    }

    public static string GetContent(DependencyObject obj)
    {
        return (string)obj.GetValue(ContentProperty);
    }
    public static readonly DependencyProperty ContentProperty = DependencyProperty.RegisterAttached("Content", typeof(string), typeof(MyClass), new PropertyMetadata(null, new PropertyChangedCallback(
        (x, y) =>
        {
            if (GetContent(x) != String.Empty)
                ((Button)GetParent(x)).Content = GetContent(x);
        })));
}

When mouse is over textbox then parent's property content changes to value of attached property set in setter

<Setter Property="local:MyClass.Content" Value="tekst"/>