How to use PropertyChangedCallBack

Question

I have a TextBox Binded to a dependancy property, I have implemented a PropertyChangedCallBack function, when the text changes I need to call textbox.ScrollToEnd() but I cant since the PropertChanged function need to be static, is there a way around this?

static FrameworkPropertyMetadata propertyMetaData = new FrameworkPropertyMetadata
(
    "MyWindow",
    FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
    new PropertyChangedCallback(TextProperty_PropertyChanged)
);

public static readonly DependencyProperty TextProperty = DependencyProperty.Register
(
    "TextProperty", 
    typeof(string), 
    typeof(OutputPanel),
    propertyMetaData
);

private void TextProperty_PropertyChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
    textbox.ScrollToEnd(); //An object reference is required for the non-static field.
}

public string Text
{
    get 
    { 
        return this.GetValue(TextProperty) as string;
    }
    set 
    { 
        this.SetValue(TextProperty, value);
        //textbox.ScrollToEnd(); // I originally called it here but I think it should be in the property changed function. 
    }
}

Peonage

Answer 1

The DependencyObject is the object that raised the event. You need to cast obj to the type you need. E.g.

TextBox textbox = (TextBox)obj;
textbox.ScrollToEnd();

Fryer