如何使用PropertyChangedCallBack

Question

我有一个绑定到依赖属性的TextBox，我已经实现了一个PropertyChangedCallBack函数，当文本改变时，我需要调用textbox.ScrollToEnd()，但我不能这样做，因为PropertChanged函数需要是静态的，有没有解决这个问题的方法？

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. 
    }
}

- Eamonn McEvoy

Answer 1

DependencyObject是引发事件的对象。您需要将obj强制转换为所需的类型。例如：

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

- Eugene