C# AutoComplete

The existing AutoComplete functionality only supports searching by prefix. There doesn’t seem to be any decent way to override the behavior.

Some people have implemented their own autocomplete functions by overriding the OnTextChanged event. That’s probably your best bet.

For example, you can add a ListBox just below the TextBox and set its default visibility to false. Then you can use the OnTextChanged event of the TextBox and the SelectedIndexChanged event of the ListBox to display and select items.

This seems to work pretty well as a rudimentary example:

public Form1()
{
    InitializeComponent();


    acsc = new AutoCompleteStringCollection();
    textBox1.AutoCompleteCustomSource = acsc;
    textBox1.AutoCompleteMode = AutoCompleteMode.None;
    textBox1.AutoCompleteSource = AutoCompleteSource.CustomSource;
}

private void button1_Click(object sender, EventArgs e)
{
    acsc.Add("[001] some kind of item");
    acsc.Add("[002] some other item");
    acsc.Add("[003] an orange");
    acsc.Add("[004] i like pickles");
}

void textBox1_TextChanged(object sender, System.EventArgs e)
{
    listBox1.Items.Clear();
    if (textBox1.Text.Length == 0)
    {
    hideResults();
    return;
    }

    foreach (String s in textBox1.AutoCompleteCustomSource)
    {
    if (s.Contains(textBox1.Text))
    {
        Console.WriteLine("Found text in: " + s);
        listBox1.Items.Add(s);
        listBox1.Visible = true;
    }
    }
}

void listBox1_SelectedIndexChanged(object sender, System.EventArgs e)
{
    textBox1.Text = listBox1.Items[listBox1.SelectedIndex].ToString();
    hideResults();
}

void listBox1_LostFocus(object sender, System.EventArgs e)
{
    hideResults();
}

void hideResults()
{
    listBox1.Visible = false;
}

There’s a lot more you could do without too much effort: append text to the text box, capture additional keyboard commands, and so forth.