Silverlight DataGrid MouseLeftButtonDown event not raised when clicking on rows

Question

Note: I have found a solution to my problem so I am posting this for reference purposes, although I would be happy to be educated with a better solution.

I'm trying to provide double click functionality on a Silverlight DataGrid by hooking into the UIElement.MouseLeftButtonDown but when I subscribe to the DataGrid.MouseLeftButtonDown using XAML or the DataGrid.MouseLeftButtonDown += syntax, my event handler is not called when I click on the rows within the DataGrid. If I click on the Header, the event is raised.

If I subscribe to the same event at the parent UserControl level, the event handler is called successfully as you would expect based on Silverlight RoutedEvents but then I have to detect whether the click occurred on the DataGrid or somewhere else.

If I subscribe to the event using this UIElement.AddHandler syntax, as shown below, then it works as expected based on the handledEventsToo: true parameter.

dataGrid.AddHandler(UIElement.MouseLeftButtonDownEvent, 
                    new MouseButtonEventHandler(dataGrid_MouseLeftButtonDown)
                    , handledEventsToo: true);

It seems that the DataGrid implementation is marking these events as handled, prevent event bubbling, by default in one of the child UIElements, which is not what I expected initially. With more thought I can see that the click behaviour drives all sorts of things (select item, edit field etc.) so perhaps the implementation makes sense.

user1058637 user1058637 · Accepted Answer · 2012-09-14T22:45:38

I had the same problem and I used MouseLeftButtonUp which fires the event but the clickcount value is always 1.

Here is the fix for that:

private const int MOUSE_SENSITIVITY = 300;

private DateTime _previousClick;

private void exceptionsDataGrid_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
        DataGrid dg = (sender as DataGrid);
        DateTime current=DateTime.Now;
        LoggerService.Exception exception = (LoggerService.Exception)dg.SelectedItem;
        if (_previousClick != null)
        {
            TimeSpan clickSpan = current - _previousClick;
            if (clickSpan.TotalMilliseconds < MOUSE_SENSITIVITY)
            {
                MessageBox.Show("You double clicked!");
            }
        }
        _previousClick = current;
}

Silverlight DataGrid MouseLeftButtonDown event not raised when clicking on rows

1 Answers