Question

我需要一种方法让viewmodel指示视图上的XamDataGrid重新读取并以最小的麻烦重新绘制其单元格。我不希望弄乱源并做一些不可持续的解决方法来提高它的事件（源可能会改变）。

为了使它更容易理解，我有一个全局静态类，它包含一些不影响数据的视觉提示配置，但只有它们在网格中表示的方式（缩放，格式化等）。视觉动作发生在附加到该字段的IValueConverter实现中，该工作正常。有一个静态事件，当提示改变并且视图模型订阅它并且事件正常启动时会触发。现在我只需要让事件处理程序使网格重新绘制。

有什么建议吗？

编辑：一些代码，如果它有帮助：

转换器：

public class ScaleConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (targetType == typeof(double) || targetType == typeof(double?))
        {
            if (value == null && targetType == typeof(double?)) return null;  // short circuit for null->null, nothing to scale
            if (value is double) return (double)value / DisplayScale.Scale; // shortcut for direct scaling, no need to waste time on conversion
            try
            {
                return System.Convert.ToDouble(value) / DisplayScale.Scale; // for convertible values, eat conversion exception
            }
            catch (Exception) {};
            // if all esle fails return NaN
            return double.NaN; 
        }
        // fallthrough, return null, this should not happen, if it does it means converter is incomplete
        return null;
    }
 ...
}

DisplayScale global

public class DisplayScale: NotificationObject
{
    private static KeyValuePair<string, double> _ActiveScaling;
    private static readonly object _lockHandle = new object(); // note: should not contest, but just to be on the safe side
    public static event Action ScalingChanged;

    public static List<KeyValuePair<string, double>> ScaleList { get; private set; }

    static DisplayScale()
    {
        ScaleList = new List<KeyValuePair<string, double>>() 
        { 
            new KeyValuePair<string, double>("No scaling (1's)", 1d),
            new KeyValuePair<string, double>("Thousands (1,000's)", 1000d),
            new KeyValuePair<string, double>("Millions (1,000,000's)", 1000000d),
            new KeyValuePair<string, double>("Billions (1,000,000,000's)", 1000000000d)
         };
        ActiveScaling = ScaleList.First();  // OPTION: could be in per-user config
    }

    public static double Scale { get { return ActiveScaling.Value; } }
    public static KeyValuePair<string, double> ActiveScaling
    {
        get
        {
            lock (_lockHandle) return _ActiveScaling;
        }
        set
        {
            lock (_lockHandle)
            {
                _ActiveScaling = value;
                var eventCall = ScalingChanged;
                if (eventCall != null) eventCall();
            }
        }
    }
}

字段定义为

// resource
<inf:ScaleConverter x:Key="ScaleConverter" />
// field
<igDP:Field Name="Deposit" Converter="{StaticResource ScaleConverter}">

Answer 1

如果您有一个集合视图而不是简单地调用Refresh（）。

public class YourViewModel
{
  private ObservableCollection<YourDataClass> yourColl;

  public void YourViewModel()
  {
    yourColl = new ObservableCollection<YourDataClass>();
    YourCollectionView = CollectionViewSource.GetDefaultView(yourColl);
    DisplayScale.ScalingChanged += () => YourCollectionView.Refresh();
  }

  var ICollectionView yourCollView;
  public ICollectionView YourCollectionView
  {
    get { yourCollView; }
    set {
      yourCollView = value;
      RaisePropertyChanged("YourCollectionView");
    }
  }
}

Answer 2

我有the same issue，事实证明，即使我的ViewModel实现了INotifyPropertyChanged，我也没有在我的ObservableCollection中绑定网格行的类上实现INotifyPropertyChanged（即 YourDataClass 在punker76的回答中）。一旦我在该类上实现了它，一切都按预期开始更新。

我知道你提到“我不想弄乱这个来源”所以我不确定这个解决方案是否适合你，但我想我会分享给其他人发现这篇文章。

导致xamDataGrid重绘

2 个答案: