c# - textbox auto complete (Multi Line)

Question

I am making a auto suggestion / complete textbox in C#, i followed below link, but text box isnt showing the suggestions

How to create autosuggest textbox in windows forms?

//-------- Get all distinct description -----------------------------
OleDbCommand command = new OleDbCommand(Queries.qry16, Connection);
OleDbDataReader reader = command.ExecuteReader();

//--------- Storing ------------------------------------
while (reader.Read())
{
    namesCollection.Add(reader.GetValue(0).ToString());
}

//----------- Close after use ---------------------------------------
reader.Close();

//----------- Set the auto suggestion in description box ------------
descriptionBox.AutoCompleteMode = AutoCompleteMode.Suggest;
descriptionBox.AutoCompleteSource = AutoCompleteSource.CustomSource;
descriptionBox.AutoCompleteCustomSource = namesCollection;

Here is my code , it is in load function of winform. And the nameCollection initializtion is in constructor... kindly please help to make it working.

I am editing my post rather then creating new... I have tried the my own code in single line textbox and it worked. Now i want the same in multi line... For research i googled more then 2 days trying different codes (one with intelli sense) but it didnt worked as auto suggestion available in textbox. Can any one give me suggestion to code the whole procedure to multi line.. Thank you.

Answer 1

AutoCompleteSource does not work on multiline TextBox controls.

Wich means you need to make it from scratch:

I would make a ListBox to display the content of your autocomplete:

var listBox = new ListBox();
Controls.Add(listBox);

You need eventhandling on your textbox however this is a bit crude, so i would rewrite it to stop the keyupevent at some point:

private void textBox_KeyUp(object sender, KeyEventArgs e)
{
    var x = textBox.Left;
    var y = textBox.Top + textBox.Height;
    var width = textBox.Width + 20;
    const int height = 40;

    listBox.SetBounds(x, y, width, height );
    listBox.KeyDown += listBox_SelectedIndexChanged;

    List<string> localList = list.Where(z => z.StartsWith(textBox.Text)).ToList();
    if(localList.Any() && !string.IsNullOrEmpty(textBox.Text))
    {
        listBox.DataSource = localList;
        listBox.Show();
        listBox.Focus();

    }
}

Now all you need is a handler to set the text in your textBox:

 void listBox_SelectedIndexChanged(object sender, KeyEventArgs e)
    {
        if(e.KeyValue == (decimal) Keys.Enter)
        {
            textBox2.Text = ((ListBox)sender).SelectedItem.ToString();
            listBox.Hide();                
        }
    }

Put in null checks where appropriate