wpf_How to binding the parent in ContentPresenter

Question

hey there;

I have a custom control that passes a TextBox to ContentPresenter through Content in the middle, but I can't bind the text of the TextBox outside，The code is as follows

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApp1">
    <Style TargetType="{x:Type local:MyControl}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:MyControl}">
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition MinWidth="50" Width="3*" />
                            <ColumnDefinition Width="5*" />
                            <ColumnDefinition MinWidth="28" Width="2*"  />
                        </Grid.ColumnDefinitions>
                        <TextBlock Grid.Column="0" Text="{Binding Label}" VerticalAlignment="Center" HorizontalAlignment="Left"/>
                        <ContentPresenter Grid.Column="1" Height="20" ContentSource="InnerContent"/>
                        <TextBlock Grid.Column="2" Text="{Binding Unit}" Margin="5 0 0 0"   VerticalAlignment="Center"  HorizontalAlignment="Left"/>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

public class MyControl : Control
{
    static MyControl()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(MyControl), new FrameworkPropertyMetadata(typeof(MyControl)));
    }
    #region DataContext
    public string Label
    {
        get { return (string)GetValue(LabelProperty); }
        set { SetValue(LabelProperty, value); }
    }
    public static readonly DependencyProperty LabelProperty = DependencyProperty.Register("Label", typeof(string), typeof(MyControl), new PropertyMetadata(string.Empty));

    /// <summary>
    /// 单位
    /// </summary>
    public string Unit
    {
        get { return (string)GetValue(UnitProperty); }
        set { SetValue(UnitProperty, value); }
    }
    public static readonly DependencyProperty UnitProperty = DependencyProperty.Register("Unit", typeof(string), typeof(MyControl), new PropertyMetadata(string.Empty));

    public object InnerContent
    {
        get { return (object)GetValue(InnerContentProperty); }
        set { SetValue(InnerContentProperty, value); }
    }
    public static readonly DependencyProperty InnerContentProperty = DependencyProperty.Register("InnerContent", typeof(object), typeof(MyControl));
    #endregion
}

<Window.DataContext>
    <local:MainViewModel x:Name="mydata"/>
</Window.DataContext>
<local:MyControl Label="核定电压" Unit="电流" Height="30" Width="200" HorizontalAlignment="Left" VerticalAlignment="Top">
    <TextBox Text="{Binding ElementName=mydata, Path=InputValue,Mode=TwoWay}" />
</local:MyControl>
<TextBlock Text="{Binding ElementName=mydata, Path=InputValue,StringFormat=[{0}]}" Height="30" Width="200"  HorizontalAlignment="Left" VerticalAlignment="Top"/>

Im pretty lost here because all the stuff you find on the net is with ContentControl or ControlTemplates never found a case with contentpresenter inside a datatemplate that is nested in another contentpresenter.

Answer 1

Hi @Karl Albright .

Welcome Microsoft Q&A.

You could update your code as follows.

With ContentPresenter, most times, this does the job:

<ContentPresenter /> The default ContentSource is "Content". That means it'll look at the Content property of the templated parent and it'll take whatever it finds there for its own content.

<StackPanel>
<local:MyControl Label="Approved voltage" Unit="V" Height="30" Width="200" HorizontalAlignment="Left" VerticalAlignment="Top">
<local:MyControl.InnerContent>
<TextBox Text="{Binding InputValue,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay}"/>
</local:MyControl.InnerContent>

</local:MyControl>

        <TextBlock Text="{Binding  Path=InputValue,StringFormat=[{0}],UpdateSourceTrigger=PropertyChanged}" Height="30" Width="200"  HorizontalAlignment="Left" VerticalAlignment="Top"/>
</StackPanel>

  <Style TargetType="{x:Type local:MyControl}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:MyControl}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="50" Width="5*" />
<ColumnDefinition Width="5*" />
<ColumnDefinition MinWidth="28" Width="2*"  />
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0" Text="{TemplateBinding Label}" VerticalAlignment="Center" HorizontalAlignment="Left" FontSize="10"  Foreground="Black" />

<ContentPresenter Grid.Column="1" Height="20" Content="{TemplateBinding InnerContent}"/>
<TextBlock Grid.Column="2" Text="{TemplateBinding Unit}" Margin="5 0 0 0"   VerticalAlignment="Center"  HorizontalAlignment="Left" FontSize="20" Foreground="Black"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

Best Regards.

Jiachen Li

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