This post originated from an RSS feed registered with .NET Buzz by Scott Hanselman. Original Post: How do I automatically size (autosize) Columns in a WinForms DataGrid? Feed Title: Scott Hanselman's ComputerZen.com Feed URL: http://radio-weblogs.com/0106747/rss.xml Feed Description: Scott Hanselman's ComputerZen.com is a .NET/WebServices/XML Weblog. I offer details of obscurities (internals of ASP.NET, WebServices, XML, etc) and best practices from real world scenarios. Latest .NET Buzz Posts Latest .NET Buzz Posts by Scott Hanselman Latest Posts From Scott Hanselman's ComputerZen.com

Apparently this is, like, the problem for the ages or something, but noone on this planet has come up with a way to automatically size the columns in a DataGrid.  Sure, there's all sorts of pyscho ways that involve measuring the length of strings in DataSets with the Graphics context, yada yada.  But, since I'm binding strongly-typed Object Collections to DataGrids in WinForm apps, that doesn't work for me (and it's a little over the top, IMHO).

So, I thought about it like this:

• If you double click on the little splitter between columns they will autosize.
• Therefore, the code to autosize has been written for me; no need to measure strings, etc.
• How do I force a double click? No, wait, wrongheadedness, how do I call whatever THEY call when a double click happens?
• So, I reflectored into DataGrid.OnMouseDown and saw their custom HitTest calls a private ColAutoResize.  Ah, bingo.

If you're going to 'sin' do it with style - do it with Reflection.

private void dgLogging_DataSourceChanged(object sender, System.EventArgs e)
        {
            try
            {
                Type t = dgLogging.GetType();
                MethodInfo m = t.GetMethod("ColAutoResize",BindingFlags.NonPublic);

                for (int i = dgLogging.FirstVisibleColumn; (i < dgLogging.VisibleColumnCount); i++)
                {
                    m.Invoke(dgLogging, new object[]{i});
                }
            }
            catch (Exception ex)
            {
                System.Diagnostics.Trace.Write("Failed Resizing Columns: " + ex.ToString());
            }
        }