（WPF工具包）为列系列中的每个DataPoint设置颜色

Question

我有一个带有ColumnSeries的WPF工具包图表。该ColumnSeries在后面的代码SelectionChanged事件和默认风格，影响了该系列中的所有列

<chartingToolkit:ColumnSeries DependentValuePath="Value" IndependentValuePath="Key" ItemsSource="{Binding ColumnValues}" IsSelectionEnabled="True" SelectionChanged="ColumnSeries_SelectionChanged"> 
    <chartingToolkit:ColumnSeries.DataPointStyle> 
     <Style TargetType="chartingToolkit:ColumnDataPoint"> 
      <Setter Property="Background" Value="{StaticResource HeaderForegroundBrush}" /> 
     </Style> 
    </chartingToolkit:ColumnSeries.DataPointStyle> 
</chartingToolkit:ColumnSeries> 

我可以改变整个的ColumnSeries的风格在代码隐藏，但如何能够在单个的风格列被更改？这可能吗？

private void ColumnSeries_SelectionChanged(object sender, SelectionChangedEventArgs e) 
{ 
    Style lineStyle = new Style { TargetType = typeof(ColumnDataPoint) }; 
    lineStyle.Setters.Add(new Setter(ColumnDataPoint.BackgroundProperty, (Brush)Application.Current.Resources["Line1Brush"])); 
    ((ColumnSeries)sender).DataPointStyle = lineStyle; 
} 

Answer 1

你可以使用一个helper方法寻找在视觉树ColumnDataPoint元素，然后设置你想要的单个元素的任何属性，例如：

private void ColumnSeries_SelectionChanged(object sender, SelectionChangedEventArgs e) 
{ 
    ColumnSeries cs = sender as ColumnSeries; 
    IEnumerable<ColumnDataPoint> columns = FindVisualChildren<ColumnDataPoint>(cs); 
    foreach (var column in columns) 
    { 
     if (column.DataContext == e.AddedItems[0]) //change the background of the selected one 
     { 
      column.Background = Brushes.DarkBlue; 
      break; 
     } 
    } 

} 

private static IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) where T : DependencyObject 
{ 
    if (depObj != null) 
    { 
     int NbChild = VisualTreeHelper.GetChildrenCount(depObj); 

     for (int i = 0; i < NbChild; i++) 
     { 
      DependencyObject child = VisualTreeHelper.GetChild(depObj, i); 

      if (child != null && child is T) 
      { 
       yield return (T)child; 
      } 

      foreach (T childNiv2 in FindVisualChildren<T>(child)) 
      { 
       yield return childNiv2; 
      } 
     } 
    } 
}