Question

我希望在下载完成之前可以看到进度条。

为此，我将“Visibility”属性与名为“loadBarVisibility”的属性绑定。

XAML代码：

<ProgressBar Visibility="{Binding loadBarVisibility}" IsIndeterminate="True"/>

ViewModel代码：

public class MainViewModel : ViewModelBase
{
    public static Visibility loadBarVisibility { get; set; }
    private const String URL = "myurl";


    public MainViewModel()
    {

        loadFlux();


        if (IsInDesignMode)
        {
            // Code runs in Blend --> create design time data.
        }
        else
        {
            // Code runs "for real"
        }
    }


    public static void loadFlux()
    {
        loadBarVisibility = Visibility.Visible;

        WebClient client = new WebClient();
        client.DownloadStringAsync(new Uri(URL));
        client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(test_downloadFinished);



    }


    public static void test_downloadFinished(object sender, DownloadStringCompletedEventArgs e)
    {
        if (e.Error == null)
        {

            loadBarVisibility = Visibility.Collapsed;

        }

    }

}

但上面的代码不起作用：进度条仍然可见。

否则，当我输入“loadBarVisibility = Visibility.Collapsed;”就在“client.DownloadStringCompleted + = new DownloadStringCompletedEventHandler（test_downloadFinished）;”之后，它有效。

有没有办法解决我的问题？

非常感谢。

Answer 1

您的ViewModel需要实现接口INotifyPropertyChanged以通知您查看属性visiblilty已更改（http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.aspx)

从事件处理程序更改属性

1 个答案: