c# - Silverlight 数据网格 : Highlight an entire column when that column is sorted

Question

我的 Silverlight 应用程序中有一个 DataGrid，我想在该列排序时突出显示该列。

它在概念上与上一个问题相似:Silverlight DataGrid: Highlight an entire column .

有什么想法吗？我想也许可以将行为附加到 LayoutUpdated 事件并检查单元格以查看它是否在排序列中？

Answer 1

要完成您想做的事情，您必须解决几个问题。最大的问题是找出列何时排序比它应该的要难得多。我发现识别列已排序以使 DataGrid.ItemsSource 成为 PagedCollectionView 并在其 SortDescriptions 上收听 CollectionChanged 事件的唯一方法> 属性(property)。如果您为 ItemsSource 使用 PagedCollectionView，并且所有可以排序的列都是 DataGridBoundColumn(实际上是除 TemplateColumn 之外的任何预制件)，那么此行为应该非常接近你想做什么。

public class DataGridSortedColumnHighlightBehavior : Behavior<DataGrid>
{

    private List<DataGridRow> rows = new List<DataGridRow>();

    protected override void OnAttached()
    {
        base.OnAttached();

        AssociatedObject.LoadingRow += AssociatedObject_LoadingRow;
        AssociatedObject.UnloadingRow += AssociatedObject_UnloadingRow;

        if (AssociatedObject.ItemsSource == null)
        {
            AssociatedObject.LayoutUpdated += AssociatedObject_LayoutUpdated;
        }
        else
        {
            var collection =
                ((AssociatedObject.ItemsSource as PagedCollectionView).SortDescriptions as INotifyCollectionChanged);
            collection.CollectionChanged += DataGridSortedColumnHighlightBehavior_CollectionChanged;
        }
    }

    void AssociatedObject_UnloadingRow(object sender, DataGridRowEventArgs e)
    {
        rows.Remove(e.Row);
    }

    void AssociatedObject_LoadingRow(object sender, DataGridRowEventArgs e)
    {
        rows.Add(e.Row);
    }

    private void AssociatedObject_LayoutUpdated(object sender, EventArgs e)
    {
        if (AssociatedObject.ItemsSource != null)
        {
            AssociatedObject.LayoutUpdated -= AssociatedObject_LayoutUpdated;
            var collection =
                ((AssociatedObject.ItemsSource as PagedCollectionView).SortDescriptions as INotifyCollectionChanged);
            collection.CollectionChanged += DataGridSortedColumnHighlightBehavior_CollectionChanged;
        }
    }

    void DataGridSortedColumnHighlightBehavior_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        if(e.NewItems != null)
        {
            foreach(SortDescription sortDesc in e.NewItems)
            {
                foreach(var column in AssociatedObject.Columns)
                {
                    var boundColumn = column as DataGridBoundColumn;
                    if (boundColumn == null)
                        continue;
                    if (boundColumn.Binding.Path.Path == sortDesc.PropertyName)
                    {
                        foreach (var row in rows)
                            ColorCell(column,row,Colors.Red);
                    }
                }
            }
        }
        if(e.OldItems != null)
        {
            foreach(SortDescription sortDesc in e.OldItems)
            {
                foreach(var column in AssociatedObject.Columns)
                {
                    var boundColumn = column as DataGridBoundColumn;
                    if (boundColumn == null)
                        continue;
                    if (boundColumn.Binding.Path.Path == sortDesc.PropertyName)
                    {
                        foreach (var row in rows)
                            ColorCell(column,row,Colors.White);
                    }
                }
            }
        }
    }

    private void ColorCell(DataGridColumn column, DataGridRow item, Color color )
    {
        var content = column.GetCellContent(item);
        if (content == null)
            return;

        var parent = GetParent<DataGridCell>(content);

        if (parent != null)
            parent.Background = new SolidColorBrush(color);

    }

    public static T GetParent<T>(DependencyObject source)
        where T : DependencyObject
    {
        DependencyObject parent = VisualTreeHelper.GetParent(source);
        while (parent != null && !typeof(T).IsAssignableFrom(parent.GetType()))
        {
            parent = VisualTreeHelper.GetParent(parent);
        }
        return (T)parent;
    }        
}