Question

I’m currently in a .NET4 Windows Forms Application.

I’m trying to make something like intellisense, but very very basic.

Lets say the user is focusing a RichTextBox, and typing something like:
Search. After this specific phrase I want it to ‘auto fill’ like so: Search "" and place the caret in between the ” “.

That way when the user keeps typing the caret stays in between the ” ” like this:

Search "[usertypinghere][caretposition]"

I’m not sure how to get the current position of the caret, let alone how to keep it there.

Answer 1

It’s SelectionStart The joy is it’s part of TextBoxBase so you can have it in TextBox, RichTextBox, MaskedTextBox, or even other’s custom derivative. You’ll want to subscribe for TextChanged event to watch for “Search”, then set the SelectionStart there after autofill, then subscribe for SelectionChangedEvent for keeping the SelectionStart from veering off.

Oh, and if you got several keywords, you’ll want to combine those keyword in sort of Dictionary of Tuples to generalize the methods.

EDIT
My test code. No flicker, no overriding controls. Just plain event subscriber

private void richTextBox1_TextChanged(object sender, EventArgs e)
    {
        if (richTextBox1.Text == "Search")
        {
            richTextBox1.Text = "Search \"\"";
            richTextBox1.SelectionStart = richTextBox1.TextLength - 1;
        }

    }

    private void richTextBox1_SelectionChanged(object sender, EventArgs e)
    {
        if (richTextBox1.Text.StartsWith("Search \"") && richTextBox1.Text.EndsWith("\""))
        {
            if (richTextBox1.SelectionStart > richTextBox1.TextLength - 1)
            {
                richTextBox1.SelectionStart = richTextBox1.TextLength - 1;
            }
            if (richTextBox1.SelectionStart <= "Search \"".Length)
            {
                richTextBox1.SelectionStart = "Search\"".Length+1;
            }
        }
    }