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. 
        }
    }

Thanks,

Eamonn

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();