AutoComplete TextBox in WPF

Question

Is it possible to make a textbox autocomplete in WPF?

I found a sample where a combo box is used and the triangle is removed by editing the style template.

Answer 1

I know this is a very old question but I want to add an answer I have come up with.

First you need a handler for your normal TextChanged event handler for the TextBox:

private bool InProg;
internal void TBTextChanged(object sender, TextChangedEventArgs e)
            {
            var change = e.Changes.FirstOrDefault();
            if ( !InProg )
                {
                InProg = true;
                var culture = new CultureInfo(CultureInfo.CurrentCulture.Name);
                var source = ( (TextBox)sender );
                    if ( ( ( change.AddedLength - change.RemovedLength ) > 0 || source.Text.Length > 0 ) && !DelKeyPressed )
                        {
                         if ( Files.Where(x => x.IndexOf(source.Text, StringComparison.CurrentCultureIgnoreCase) == 0 ).Count() > 0 )
                            {
                            var _appendtxt = Files.FirstOrDefault(ap => ( culture.CompareInfo.IndexOf(ap, source.Text, CompareOptions.IgnoreCase) == 0 ));
                            _appendtxt = _appendtxt.Remove(0, change.Offset + 1);
                            source.Text += _appendtxt;
                            source.SelectionStart = change.Offset + 1;
                            source.SelectionLength = source.Text.Length;
                            }
                        }
                InProg = false;
                }
            }

Then make a simple PreviewKeyDown handler:

    private static bool DelKeyPressed;
    internal static void DelPressed(object sender, KeyEventArgs e)
    { if ( e.Key == Key.Back ) { DelKeyPressed = true; } else { DelKeyPressed = false; } }

In this example "Files" is a list of directory names created on application startup.

Then just attach the handlers:

public class YourClass
  {
  public YourClass()
    {
    YourTextbox.PreviewKeyDown += DelPressed;
    YourTextbox.TextChanged += TBTextChanged;
    }
  }

With this whatever you choose to put in the List will be used for the autocomplete box. This may not be a great option if you expect to have an enormous list for the autocomplete but in my app it only ever sees 20-50 items so it cycles through very quick.