Silverlight Datagrid row height won't decrease

Question

I am binding an ObservableCollection to a Datagrid. Everything is working besides this row height issue I've been fighting for a while now.

The Issue is the row heights are storing the largest cell's height and not changing from that.

If I have a collection of 5 objects. In ASC order,Row 1 height is 100 and row 5 height is 20. If I resort the same column to DESC then row 1 height is now 100 and row 5 height is 100 as well.

I've tried wrapping the Datagrid in a Scrollviewer and changed DataGridTextColumn to DataGridTemplateColumn with a vertical aligned text box. Silverlight doesn't have ViewCollectionSource so I couldn't try that one.

How can I get it to recalculate the height after a sort?

XAML

        SelectedItem="{Binding SelectedComment, Mode=TwoWay}"
        VerticalAlignment="Top"
        Width="1000"
        Height="Auto"
        >
         <sdk:DataGrid.Columns>
                <sdk:DataGridTemplateColumn Header ="Comment" Width="4*" IsReadOnly="True" SortMemberPath="Commentstr" CanUserSort="True">
                    <sdk:DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <TextBlock Text="{Binding Commentstr}" TextWrapping="Wrap" VerticalAlignment="Top"></TextBlock>
                        </DataTemplate>
                    </sdk:DataGridTemplateColumn.CellTemplate>
                </sdk:DataGridTemplateColumn>

            </sdk:DataGrid.Columns>
        </sdk:DataGrid>

Code-Behind

 private ObservableCollection<Comment> commentCollection = new ObservableCollection<Comment>();
    public ObservableCollection<Comment> CommentCollection
    {
        get { return commentCollection; }
        set
        {
            commentCollection = value;
        }
    }
    public Main()
    {
        InitializeComponent();
        this.Loaded += new RoutedEventHandler(CustomScreenTemplate_Loaded);

        CommentGrid.ItemsSource = CommentCollection;
    }

user2312013 user2312013 · Accepted Answer · 2016-10-28T18:33:02

Finally got the row height issue resolved. Posting what worked for me here in case anyone else has the same problem.

Creat an Override Class for DataGrid

public class FixedDataGrid : DataGrid
{
    /// <summary>
    /// Overrides OnLoadingRow
    /// </summary>
    protected override void OnLoadingRow(DataGridRowEventArgs e)
    {
        if (double.IsNaN(this.RowHeight))
        {
            e.Row.Loaded += Row_Loaded;
        }

        base.OnLoadingRow(e);
    }

    private void Row_Loaded(object sender, RoutedEventArgs e)
    {
        var row = (DataGridRow)sender;
        row.Loaded -= Row_Loaded;

        for (int col = 0; col < this.Columns.Count; col++)
        {
            var cellElement = this.Columns[col].GetCellContent(row);
            if (cellElement != null)
            {
                cellElement.SizeChanged += CellElement_SizeChanged;
            }
        }
    }

    private static void CellElement_SizeChanged(object sender, SizeChangedEventArgs e)
    {
        //Fix issue: DataGrid Row Auto-Resize only grows row height but won't shrink
        var dataGrid = GetParentOf<DataGrid>((FrameworkElement)sender);
        if (dataGrid != null && double.IsNaN(dataGrid.RowHeight))
        {
            var row = DataGridRow.GetRowContainingElement((FrameworkElement)sender);

            //Fore recalculating row height
            try
            {
                dataGrid.RowHeight = 0;
                row.InvalidateMeasure();
                row.Measure(row.RenderSize);
            }
            finally
            {
                //Restore RowHeight
                dataGrid.RowHeight = double.NaN;
            }
        }
    }

    private static T GetParentOf<T>(FrameworkElement element) where T : FrameworkElement
    {
        while (element != null)
        {
            T item = element as T;
            if (item != null)
            {
                return item;
            }

            element = (FrameworkElement)VisualTreeHelper.GetParent(element);
        }

        return null;
    }
}

Use the override class as your Datagrid

xmlns:fixed="clr-namespace:MyNameSpace

<fixed:FixedDataGrid x:Name="BetterGrid"  ... />

Silverlight Datagrid row height won't decrease

1 Answers