Size RichTextBox according to contents

Question

This code automatically sizes a RichTextBox according to it's contents. I'm having issues, especially with tables. \t may be ignored. I tried a managed solution, now I'm trying platform invoke. Current Output:

    [DllImport("gdi32.dll")]
    static extern bool GetTextExtentPoint32(IntPtr hdc, string lpString, int cbString, out SIZE lpSize);

    [DllImport("user32.dll", SetLastError = true)]
    static extern IntPtr GetDC(IntPtr hWnd);

    [StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
    public struct SIZE
    {
        public int cx;
        public int cy;

        public SIZE(int cx, int cy)
        {
            this.cx = cx;
            this.cy = cy;
        }
    }

    public static void Main()
    {
        Form form = new Form();
        RichTextBox rtfBox = new RichTextBox();

        rtfBox.Rtf = @"{\rtf1\ansi\deff0{\fonttbl{\f0\fnil Arial;}}\viewkind4\uc1\trowd\trgaph100\cellx1000\cellx2000\pard\intbl\lang1033\f0\fs20  hi\cell  bye\cell\row\intbl  one\cell  two\cell\row\pard\par}";
        rtfBox.ScrollBars = RichTextBoxScrollBars.None;

        string sInput = "hi\t bye\t\n";// one\t two\t\n";
        SIZE CharSize;

        form.Controls.Add(rtfBox);

        IntPtr hdc = GetDC(IntPtr.Zero);//Context for entire screen
        GetTextExtentPoint32(hdc, sInput, sInput.Length, out CharSize);

        rtfBox.Width = CharSize.cx;
        rtfBox.Height = CharSize.cy;

        form.Visible = false;

        form.ShowDialog();
    }

(Note, for simplicity this is a console application with a reference to System.Windows.Forms.dll)

Answer 1

Have you looked at the ContentsResized event? Add the following method to be called when the event fires:

private void richTextBox_ContentsResized(object sender, ContentsResizedEventArgs e)
{
    var richTextBox = (RichTextBox) sender;
    richTextBox.Width = e.NewRectangle.Width;
    richTextBox.Height = e.NewRectangle.Height;
}

When the RTF content is changed (using Rtf), the RichTextBox should be resized to match its contents. Make sure you also set the WordWrap property to false.

---

I've tried it with your table example and it does appear to work (albeit with a little offset, which you could possibly solve by adding a few pixels of width to the adjusted size - not sure why that happens):

P.Brian.Mackey EDIT
This answer worked for me. To clarify, here's the final code including border fix:

    public static void Main()
    {
        string sInput = "hi\t bye\t\n";// one\t two\t\n";
        SIZE CharSize;
        Form form = new Form();
        RichTextBox rtfBox = new RichTextBox();
        rtfBox.ContentsResized += (object sender, ContentsResizedEventArgs e) =>
        {
            var richTextBox = (RichTextBox)sender;
            richTextBox.Width = e.NewRectangle.Width;
            richTextBox.Height = e.NewRectangle.Height;
            rtfBox.Width += rtfBox.Margin.Horizontal + SystemInformation.HorizontalResizeBorderThickness;
        };

        rtfBox.WordWrap = false;
        rtfBox.ScrollBars = RichTextBoxScrollBars.None;

        rtfBox.Rtf = @"{\rtf1\ansi\deff0{\fonttbl{\f0\fnil Arial;}}\viewkind4\uc1\trowd\trgaph100\cellx1000\cellx2000\pard\intbl\lang1033\f0\fs20  hi\cell  bye\cell\row\intbl  one\cell  two\cell\row\pard\par}";

        form.Controls.Add(rtfBox);
        form.ShowDialog();
    }