caliburn.micro - Caliburn Micro：如何在列表框底部添加文本并显示

Question

我试图弄清楚如何将文本添加到列表框的底部并显示它。在带有代码的 WPF 中，我会抓住 ScrollViewer 并对其进行操作，但我不知道如何使用 Caliburn 来完成它......

Answer 1

你有几个选择。

1) 在您的 ViewModel 中，您可以调用GetView并将其转换为您的视图类型并获取对 ScrollViewer 的引用。就像是：

var myView = this.GetView() as MyView;
var myScrollView = myView.MyScrollView;

这可以正常工作，但如果您试图不将视图耦合到视图模型，则并不理想。

选项 2) 是实现 IResult，请参阅此处的文档。

public class ScrollViewResult : IResult
    {
        public event EventHandler<ResultCompletionEventArgs> Completed = delegate { };

        private ScrollViewResult ()
        {
        }

        public void Execute (ActionExecutionContext context)
        {
            var view = context.View as FrameworkElement;
            var scrollViewer = FindVisualChild<ScrollViewer>(view);

            //do stuff to scrollViewer here

            Completed (this, new ResultCompletionEventArgs { });
        }

        private static TChildItem FindVisualChild<TChildItem> (DependencyObject obj)
            where TChildItem : DependencyObject
        {
            for (var i = 0; i < VisualTreeHelper.GetChildrenCount (obj); i++)
            {
                var child = VisualTreeHelper.GetChild (obj, i);
                if (child != null && child is TChildItem)
                    return (TChildItem)child;

                var childOfChild = FindVisualChild<TChildItem> (child);
                if (childOfChild != null)
                    return childOfChild;
            }
            return null;
        }

        //this isn't required of course but comes in handy for 
        //having a static method and passing parameters to the
        //ctor of the IResult
        public static IResult DoSomething ()
        {
            return new ScrollViewResult ();
        }

然后你可以这样称呼它：

public IEnumerable<IResult> SomeAction()
        {
            yield return ScrollViewResult.DoSomething();
        }