WPF UserControl Binding - OnPropertyChanged call Function

Question

Good evening! I have read multiple threads about binding and thought I got the hang of it (at least for textBoxes, ObservableCollections, etc.). Now however, I have a bit more complicated problem and got lost somewhere:

I created a UserControl (STATUSBOX), containing labels etc. I am binding those labels like this:

 <Label x:Name="c1" x:FieldModifier="private" Grid.Column="1" 
    Grid.Row="1" Height="20" Style="{StaticResource labelTable}" 
    Width="140" Content="{Binding Path= value1}" Margin="0,0,0,0" ></Label>

In the code behind, I implemented it like that:

public String value1
    {
        get { return (String)GetValue(ValueProperty1); }
        set {
                SetValue(ValueProperty1, value); 
                //setLightColor(1, value); //[I]
            }
    }
    public static readonly DependencyProperty ValueProperty1 =
        DependencyProperty.Register("value1", typeof(string),
          typeof(UC_StatusBox_detailed), new PropertyMetadata(null));

That works just fine.

Now however, I try to add a status light which switches between green-orarnge-red. Therefore, I created a new UserControl (LAMPCONTROL) which displays part of a sprite image:

<Border x:Name="frame" x:FieldModifier="private" Width="30" Height="30" Grid.Column="0" 
    Grid.Row="0" CornerRadius="4" BorderThickness="1">
    <Rectangle Height="30" Width="30" Grid.Column="0" 
        HorizontalAlignment="Right" VerticalAlignment="Center">
            <Rectangle.Fill>
                <ImageBrush x:Name="imgBrush" x:FieldModifier="private" ViewboxUnits="Absolute" Viewbox="0,0, 30,30" ImageSource="/TestControl;component/Icons/spriteLight.png"/>
            </Rectangle.Fill>
    </Rectangle>            
</Border>

I added the following method:

private void UpdateLightStatus(Boolean statusOK)
    {
        int offset;         
        if (statusOK)
        {
            offset = 0;
        }
        else
        {
            offset = 30;
        }
        this.imgBrush.Viewbox = new Rect(offset, 0, 30, 30);
    }

That also works, if I use it "stand alone".

However if I try to implement this in my STATUSBOX, I am having trouble to get it working... I was hoping to do something like here [I] and all is done, but that does not work. In the next approach, I tried to create a DependencyProperty in the LAMPCONTROL equal to those in the STATUSBOX and add a binding in the xaml of the LAMPCONTROL and from there on I got a bit confused.

The question - in short - would be: How to call a method of a sub-UserControl from the main-UserControl when the bound property of the main-UserControl is changed?

I hope it is a bit understandable what my problem is, if more info is required, I am happy to provide that, but I didn't want to make this question even larger than it is now...

Thank you for reading all of that and best regards

Fabian

---

Clemens put me in the right direction. The solution is below

Answer 1

Clemens put me in the right direction. The solution is as follows:

public static readonly DependencyProperty Value1Property =
    DependencyProperty.Register("Value1", typeof(string),
      typeof(UC_StatusBox_detailed), new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender,
          new PropertyChangedCallback(OnValueChanged)));


private static void OnValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
//my code here
}