WPF绑定到父窗口中的元素

Question

I'm trying to bind element's property in a child control to an element's property ina parent window, it doesn't work..

Here is png of what I'm trying to do:

Here is the xaml that doesn't work:

CurrentDate="{Binding ElementName=TimeBar, Path=SelectionStart,RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}}" 

Thanks.

Answer 1

create a dependency property in your usercontrol and then bind to it in your window

something like that: DependencyProperty implementations you can find all around here on stackoverflow

<YourUsercontrol x:Name="uc">
  <YourSomeControl CurrentDate="{Binding ElementName=uc, Path=MyDp}"/>
 </YourUsercontrol>

xaml window

 <Window>
   <ElementInParent x:Name="eip" />
   <YourUsercontrol MyDp="{Binding ElementName=eip, Path=PropertyFromElementInParent}"/>

Answer 2

根据以下答案链接 ，SelectionStart默认情况下不是Bindable Probperty，因此您需要创建附加行为或类似的东西

Answer 3

Binding ElementName along with Relative Source is not correct approach. Besides the UserControl does not know the ElementName of the Parent since the two are in different XAML.

One approach is to set the data context of user control with the element name you want to bind it to and then use normal binding Path.

As shown in the example below: In main window, we have a textbox and a user control. We are setting data context of the user control with the text box.

In the user control, we are binding the Text property of the DataContext (which is essentially TextBox of main window).

<Window
     xmlns:self="clr-namespace:experiments"
     >
    <StackPanel>
        <TextBox x:Name="Name" Width="100"/>
        <self:UserControl1 DataContext="{Binding ElementName=Name}"/>
    </StackPanel>
</Window>



<UserControl x:Class="experiments.UserControl1">
    <Grid>
        <TextBlock Text="{Binding Path=Text}" Width="100" Background="AliceBlue" Height="50"/>
    </Grid>
</UserControl>