关于WPF异步MVVM等待窗体的介绍

///

  /// 在MVVM模式中ViewModel的状态
  ///

  [Flags]
  public enum ViewModelStatus
  {
    ///

    /// ViewModel无状态
    ///

    NOne= 0x0,
    ///

    /// ViewModel正在初始化
    ///

    Initializing = 0x1,
    ///

    /// ViewModel初始化完毕
    ///

    Initialized = 0x2,
    ///

    /// ViewModel正在加载
    ///

    Loading = 0x4,
    ///

    /// ViewModel加载完毕
    ///

    Loaded = 0x8,
    ///

    /// ViewModel正在保存
    ///

    Saving = 0x16,
    ///

    /// ViewModel保存完毕
    ///

    Saved = 0x32
  }

public class StatusToAnimationVisibilityConverter : IValueConverter
   {
     #region IValueConverter Members

     public object Convert(
       object value, Type targetType, object parameter, CultureInfo culture)
     {
       try
       {
         string status = value.ToString();

         switch (status)
         {
           case "Initializing":
           case "Loading":
           case "Saving":
             return Visibility.Visible;
           case "Loaded":
           case "Saved":
           default:
             return Visibility.Collapsed;
         }
       }
       catch (Exception)
       {
         return Visibility.Collapsed;
       }
     }

     public object ConvertBack(
       object value, Type targetType, object parameter, CultureInfo culture)
     {
       return DependencyProperty.UnsetValue;
     }

     #endregion
   }

///

   /// 响应式的ViewModel模型
   ///

   public abstract class ViewModelResponsive : ViewModelBase, IViewModelResponsive
   {
     #region Fields

     private ViewModelStatus _status = ViewModelStatus.None;

     #endregion

     #region ViewModel Status

     ///

     /// 刷新UI数据
     ///

     public virtual void Refresh()
     {

     }

     ///

     /// ViewModel状态
     ///

     public ViewModelStatus Status
     {
       get
       {
         return _status;
       }
       protected set
       {
         if (_status != value)
         {
           _status = value;
           RaisePropertyChanged(@"Status");
         }
       }
     }

     #endregion
   }

public class CameraManagementViewModel : ViewModelResponsive
   {
     protected override void BindCommands()
     {
       RefreshCommand = new RelayCommand(() =>
       {
         Refresh();
       });
     }

     public override void Refresh()
     {
       base.Refresh();

       Status = ViewModelStatus.Initializing;
       CameraCollection.Clear();
       Model.GetCameras(GetCamerasCallback);
     }

     private void GetCamerasCallback(object sender, AsyncWorkerCallbackEventArgs> args)
     {
       CameraCollection.Clear();
       Status = ViewModelStatus.Loaded;

       if (result)
       {
         foreach (var item in (args.Data as IList))
         {
           CameraCollection.Add(item);
         }
       }
     }
   }