Question

I have

<DataGrid Name="grid" MouseDoubleClick="Attributes_MouseDoubleClick" >

I need to unselect a row whenever a click event occurs anywhere else other than the Datagrid row.

i.e. grid.CurrentItem should be null

I need to fire a double-click event only on a row.
But, the problem is, once I select a row and double-click elsewhere on the grid(header, empty scrollviewer area, etc) the double-click event fires as expected but the CurrentItem is sometimes the selected row and sometimes null.

To prevent this behaviour.. I need to unselect the selected row.

Any ideas as to how I should approach this?

Thanks.

Answer 1

You can search the Visual Tree of the event source for an instance of type DataGridRow to determine if you double clicked on a row or somewhere else.

The following site Detecting Double Click Events on the WPF DataGrid contains good example.
I’ve include the code here in case the site is no longer available.

Here is the event handler for double click:

private void DataGridRow_MouseDoubleClick(object sender, MouseButtonEventArgs e)
{
  //search the object hierarchy for a datagrid row
  DependencyObject source = (DependencyObject)e.OriginalSource;
  var row = DataGridTextBox.Helpers.UIHelpers.TryFindParent<DataGridRow>(source);

  //the user did not click on a row
  if (row == null) return;

  //[insert great code here...]

  e.Handled = true;
}

Here is the code to help search the Visual Tree:

using System.Windows;
using System.Windows.Media;

namespace DataGridTextBox.Helpers
{
  public static class UIHelpers
  {
    public static T TryFindParent<T>(this DependencyObject child) where T : DependencyObject
    {
      //get parent item
      DependencyObject parentObject = GetParentObject(child);

      //we've reached the end of the tree
      if (parentObject == null) return null;

      //check if the parent matches the type we're looking for
      T parent = parentObject as T;
      if (parent != null)
      {
        return parent;
      }
      else
      {
        //use recursion to proceed with next level
        return TryFindParent<T>(parentObject);
      }
    }

    public static DependencyObject GetParentObject(this DependencyObject child)
    {
      if (child == null) return null;

      //handle content elements separately
      ContentElement contentElement = child as ContentElement;
      if (contentElement != null)
      {
        DependencyObject parent = ContentOperations.GetParent(contentElement);
        if (parent != null) return parent;

        FrameworkContentElement fce = contentElement as FrameworkContentElement;
        return fce != null ? fce.Parent : null;
      }

      //also try searching for parent in framework elements (such as DockPanel, etc)
      FrameworkElement frameworkElement = child as FrameworkElement;
      if (frameworkElement != null)
      {
        DependencyObject parent = frameworkElement.Parent;
        if (parent != null) return parent;
      }

      //if it's not a ContentElement/FrameworkElement, rely on VisualTreeHelper
      return VisualTreeHelper.GetParent(child);
    }
  }
}