如何使用 PropertyChangedCallBack

Question

我有一個 TextBox 綁定到一個依賴屬性，我已經實現了一個 PropertyChangedCallBack 函數，當文本更改時我需要調用 textbox.ScrollToEnd() 但我不能，因為 PropertChanged 函數需要是靜態的，有沒有辦法解決這個問題？

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. 
    }
}

Answer 1

DependencyObject是引發事件的對象。 您需要將obj轉換為您需要的類型。 例如

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