Is there any way to use autocomplete with multiple words inside the textbox in a winform?

Question

I want to show the suggested words using autocomplete for the textbox. For instance, i type Tod... all words from my database that starts with \"tod\" will show but after I chos

Answer 1

So a basic "Roll Your Own" solution will work like so:

string[] arr = new string[] { "sn k", "sn k", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sept", "Oct", "Nov", "Dec" };

private ListBox autoListBox;

private void Form1_Load(object sender, EventArgs e)
{
    this.txtInput.TextChanged += txtInput_TextChanged;
    CreateAutocompleteListBox();
}

private void txtInput_TextChanged(object sender, EventArgs e)
{
    showAutoCompleteList();
}

private void CreateAutocompleteListBox()
{
    this.autoListBox = new ListBox()
    {
        Left = this.txtInput.Left,
        Top = this.txtInput.Top + this.txtInput.Height,
        Width = 100,
        Height = 75
    };

    this.autoListBox.Click += autoListBox_Click;
    this.autoListBox.KeyDown += autoListBox_KeyDown;
    this.autoListBox.Visible = false;
    this.Controls.Add(this.autoListBox);
}

private void autoListBox_Click(object sender, EventArgs e)
{
    AutocompleteFinished();
}

private void autoListBox_KeyDown(object sender, KeyEventArgs e)
{
    var finishCodes = new List { Keys.Return, Keys.Space };
    if (finishCodes.Contains(e.KeyCode))
    {
        AutocompleteFinished();
    }
}

private string GetLastWord(TextBox txt)
{
    return (" " + txt.Text).Split(' ').LastOrDefault() ?? "";
}

private void showAutoCompleteList()
{
    this.autoListBox.Left = this.txtInput.Left;
    this.autoListBox.Top = this.txtInput.Top + this.txtInput.Height + 2;
    var lastWord = GetLastWord(this.txtInput);

    this.autoListBox.Items.Clear();
    this.autoListBox.Items.AddRange(this.arr.Where(aw => aw.ToLower().StartsWith(lastWord.ToLower())).ToArray());
    this.autoListBox.Visible = true;
}

private void txtInput_KeyDown(object sender, KeyEventArgs e)
{
    // These keys show auto-complete selector
    var activatorCodes = new List { Keys.Up, Keys.Down };
    if (activatorCodes.Contains(e.KeyCode))
    {
        SwitchToAutoCompleteList();
    }
}

private void SwitchToAutoCompleteList()
{
    this.autoListBox.Focus();
    this.autoListBox.SelectedIndex = 0;
}

private void AutocompleteFinished()
{
    var lastWord = GetLastWord(this.txtInput);
    var nextWord = this.autoListBox.Text;
    this.txtInput.Text = this.txtInput.Text.Substring(0, this.txtInput.Text.Length - lastWord.Length);
    this.txtInput.AppendText(nextWord);
    this.autoListBox.Visible = false;
}

This ought to do what you want, it will show autocomplete for each word! One could add a little finesse, such as moving the autocomplete box around as the text moves on.