Question

I am generating a DataGrid dynamically and adding it to a StackPanel on my WPF application.

As the is dynamically generated, there is no mark up on XAML side for the same and I need to manage the binding and all properties programatically.

I want my DataGrid to have the values in the cell wrapped to the next line if the text is lengthy. I understand that I need to replace the DataGridCell with TextBlock and set the TextWrap property on it. All the examples that I have found suggest something on those lines itself. However, I couldn’t find a way to do it completely from code behind, without XAML.

So far, I have tried to the following code, but it doesn’t work.

DataGrid dg = new DataGrid();   

dg.ItemsSource = ((DataSet)data).Tables[0].DefaultView;
dg.DataContext = ((DataSet)data).Tables[0].DefaultView; 

DataTemplate ct = new DataTemplate(typeof(DataGridCell));
FrameworkElementFactory tb = new FrameworkElementFactory(typeof(TextBlock));
tb.SetValue(TextBlock.TextWrappingProperty, TextWrapping.Wrap);
ct.VisualTree = tb;

dg.ItemTemplate = ct;
dg.ColumnWidth = 300;

Can you please point me to the right direction here?

[Update]: Solution

On further researching I was able to get a solution to my issue. For Auto generated columns, we need to capture the AutoGeneratingColumn event and replace the default DataGridTextColumn by a DataGridTemplateColumn which would have a TextBlock in it. And we can then set the `TextWrappingProperty’ to get the text wrapped.

Following is the updated code:

DataGrid dg = new DataGrid();   

dg.ItemsSource = ((DataSet)data).Tables[0].DefaultView;
dg.DataContext = ((DataSet)data).Tables[0].DefaultView; 

DataTemplate ct = new DataTemplate(typeof(DataGridCell));
FrameworkElementFactory tb = new FrameworkElementFactory(typeof(TextBlock));
tb.SetValue(TextBlock.TextWrappingProperty, TextWrapping.Wrap);
ct.VisualTree = tb;

dg.AutoGeneratingColumn += new EventHandler<DataGridAutoGeneratingColumnEventArgs>(dg_AutoGeneratingColumn);

dg.MaxColumnWidth = 300;

and then the Code under the Event Handler:

 private void dg_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
        {
        //cancel the auto generated column
        e.Cancel = true;

        //Get the existing column
        DataGridTextColumn dgTextC = (DataGridTextColumn)e.Column;

        //Create a new template column 
        DataGridTemplateColumn dgtc = new DataGridTemplateColumn();

        DataTemplate dataTemplate = new DataTemplate(typeof(DataGridCell));

        FrameworkElementFactory tb = new FrameworkElementFactory(typeof(TextBlock));
        tb.SetValue(TextBlock.TextWrappingProperty, TextWrapping.Wrap);
        dataTemplate.VisualTree = tb;

        dgtc.Header = dgTextC.Header;
        dgtc.CellTemplate = dataTemplate;

        tb.SetBinding(TextBlock.TextProperty, dgTextC.Binding);

        //add column back to data grid
        DataGrid dg = sender as DataGrid;
        dg.Columns.Add(dgtc);
    }

Answer 1

An alternate approach is to use a behaviour like this.

  public class DataGridWrapTextBehaviour : Behavior<DataGrid>
  {
     private DataGrid DataGrid
     {
        get { return AssociatedObject as DataGrid; }
     }

     private Style ElementStyle { get; set; }
     private Style EditingElementStyle { get; set; }

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

        this.ElementStyle = new Style( typeof( TextBlock ) );
        this.ElementStyle.Setters.Add( new Setter( TextBlock.TextWrappingProperty, TextWrapping.Wrap ) );

        this.EditingElementStyle = new Style( typeof( TextBox ) );
        this.EditingElementStyle.Setters.Add( new Setter( TextBox.TextWrappingProperty, TextWrapping.Wrap ) );

        this.DataGrid.Columns.CollectionChanged += Columns_CollectionChanged;
     }

     protected override void OnDetaching()
     {
        this.DataGrid.Columns.CollectionChanged -= Columns_CollectionChanged;
        base.OnDetaching();
     }

     private void Columns_CollectionChanged( object sender, NotifyCollectionChangedEventArgs e )
     {
        foreach ( var column in this.DataGrid.Columns.OfType<DataGridTextColumn>() )
        {
           column.ElementStyle = this.ElementStyle;
           column.EditingElementStyle = this.EditingElementStyle;
        }
     }
  }

You can then drap and drop the behaviour onto the DataGrid in Expression Blend.