wpf - 绑定(bind)到 WPF ViewModel 属性

Question

我只是在玩 WPF 和 MVVM，我制作了一个简单的应用程序，它显示一个 Rectangle，只要网络可用性发生变化，它就会改变颜色。

但是当这种情况发生时，我会收到这个错误:Cannot use a DependencyObject that belongs to a different thread than its parent Freezable.
代码

XAML

<Window x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="400" Width="600">
<DockPanel LastChildFill="True">
    <Rectangle x:Name="networkStatusRectangle" Width="200" Height="200" Fill="{Binding NetworkStatusColor}" />
</DockPanel>
</Window>

代码隐藏

使用 System.Windows；
使用 WpfApplication1.ViewModels；

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            DataContext = new NetworkViewModel();
        }
    }
}

查看型号

using System.ComponentModel;
using System.Net.NetworkInformation;
using System.Windows.Media;

namespace WpfApplication1.ViewModels
{
    public class NetworkViewModel : INotifyPropertyChanged
    {
        private Brush _NetworkStatusColor;

        public Brush NetworkStatusColor
        {
            get { return _NetworkStatusColor; }
            set
            {
                _NetworkStatusColor = value;
                NotifyOfPropertyChange("NetworkStatusColor");
            }
        }

        public NetworkViewModel()
        {
            NetworkChange.NetworkAvailabilityChanged += new NetworkAvailabilityChangedEventHandler(NetworkChange_NetworkAvailabilityChanged);
        }

        protected void NetworkChange_NetworkAvailabilityChanged(object sender, NetworkAvailabilityEventArgs e)
        {
            if (e.IsAvailable)
            {
                this.NetworkStatusColor = new SolidColorBrush(Colors.Green);
            }
            else
            {
                this.NetworkStatusColor = new SolidColorBrush(Colors.Red);
            }
        }

        public event PropertyChangedEventHandler PropertyChanged = delegate { };

        public void NotifyOfPropertyChange(string propertyName)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

我假设我应该通过调用某些东西来更改 NetworkStatusColor 属性？

Answer 1

你假设正确。这是Dispatcher类和 .Invoke你想看看的方法。

有点像这样:

if (this.Dispatcher.Thread != Thread.CurrentThread)
{
    this.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(...your method...), any, params, here);
    return
}

有一个 MSDN article here有更多信息。