DependencyProperty可以绑定两次到TwoWay绑定吗？

Question

I have a Control that displays something (let's call it Display ). In this control I have a class Camera that stores things like zoom, position and rotation.

I can change the zoom from an external control (let's call it ZoomBar ).

Now I had the idea to connect all of them with a TwoWay-Binding like this:

ZoomBar.Value <--> Display.Zoom <--> Camera.Zoom

It should be like: ZoomBar value changes --> update Display.Zoom --> update Camera.Zoom . Display.Zoom does not really do something. It's only for exchange the data between Camera and ZoomBar .

But I get nothing. After a short check in the Camera:

public float Zoom
{
  get { MessageBox.Show("Any calls here?"); return (float)GetValue(ZoomProperty); }
  set { ... }
}

I get a massive amount of MessageBoxes. I guess there is something like loop in there. Like ZoomBar.Value --> Display.Zoom --> ZoomBar.Value --> ...

---

My question

Are the two-way bindings causing the problem and if it is the bindings, is there a XAML way to fix this?

---

XAML ZoomBar

<StatusBarItem Title="Zoom Bar" HorizontalAlignment="Right">
  <Slider x:Name="uxInputZoom" Style="{DynamicResource ZoomSliderStyle}" Value="100" Maximum="500" Minimum="20" />
</StatusBarItem>

XAML Display

<Display x:Name="uxDisplay" Zoom="{Binding Value, Converter={StaticResource PercentToFractionConverter}, ElementName=uxInputZoom, Mode=TwoWay}" />

Code Display

public static readonly DependencyProperty ZoomProperty = DependencyProperty.Register("Zoom", typeof(float), typeof(Display), new FrameworkPropertyMetadata(1f));

public float Zoom
{
  get { return (float)GetValue(ZoomProperty); }
  set { SetValue(ZoomProperty, value); }
}

Camera _camera = new Camera();

//...

public Display()
{
  Binding binding = new Binding("Zoom");
  binding.Source = _camera;
  binding.Mode = BindingMode.TwoWay;

  BindingOperations.SetBinding(this, Display.ZoomProperty, binding);

  InitializeComponent();

  ...
}

Answer 1

You certainly can data bind one property value to more than one UI control. Take this simple example which enables movements of the Slider to update the value in the TextBox , while also enabling values entered in the TextBox to update the Slider.Value property:

<StackPanel>
    <Slider Value="{Binding Width2}" Minimum="0.0" Maximum="100.0" Margin="0,0,0,20" />
    <TextBox Text="{Binding Width2, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>

This will not cause any feedback loops as in your code, so I suspect that you have something else doing that.