Question

How do I get the current line and column numbers in a RichTextBox in a Winforms application?

NOTE

Folks, I just want a simple solution, if it’s available by someone and he’s willing to share it with us, and not links to do research! Just give me some code please! Otherwise, I’ll have to buy a control…

Answer 1

For row and column, check out the Richer RichTextBox project. It is an extended version of the RichTextBox which supports the row and column numbers. The code from the article:

this.rtb.CursorPositionChanged += 
    new System.EventHandler(this.rtb_CursorPositionChanged);
this.rtb.SelectionChanged += 
    new System.EventHandler(this.rtb_SelectionChanged);
.
.
.
private void rtb_CursorPositionChanged(object sender, System.EventArgs e)
{
    int line = rtb.CurrentLine;
    int col = rtb.CurrentColumn;
    int pos = rtb.CurrentPosition;

    statusBar.Text = "Line " + line + ", Col " + col + 
                     ", Position " + pos;
}

private void rtb_SelectionChanged(object sender, System.EventArgs e)
{
    int start = rtb.SelectionStart;
    int end = rtb.SelectionEnd;
    int length = rtb.SelectionLength;

    statusBar.Text = "Start " + start + ", End " + end + 
                     ", Length " + length;
}

To achieve such behavior, we need to extend the RichTextBox class in the following manner:

using System;
using System.Drawing;
using System.Windows.Forms;

namespace Nik.UserControls
{
    public class RicherTextBox2 : System.Windows.Forms.RichTextBox
    {
        public event EventHandler CursorPositionChanged;

        protected virtual void OnCursorPositionChanged( EventArgs e )
        {
            if ( CursorPositionChanged != null )
                CursorPositionChanged( this, e );
        }

        protected override void OnSelectionChanged( EventArgs e )
        {
            if ( SelectionLength == 0 )
                OnCursorPositionChanged( e );
            else
                base.OnSelectionChanged( e );
        }

        public int CurrentColumn
        {
            get { return CursorPosition.Column( this, SelectionStart ); }
        }

        public int CurrentLine
        {
            get { return CursorPosition.Line( this, SelectionStart ); }
        }

        public int CurrentPosition
        {
            get { return this.SelectionStart; }
        }

        public int SelectionEnd
        {
            get { return SelectionStart + SelectionLength; }
        }
    }

    internal class CursorPosition
    {
        [System.Runtime.InteropServices.DllImport("user32")] 
        public static extern int GetCaretPos(ref Point lpPoint);

        private static int GetCorrection(RichTextBox e, int index)
        {
            Point pt1 = Point.Empty;
            GetCaretPos(ref pt1);
            Point pt2 = e.GetPositionFromCharIndex(index);

            if ( pt1 != pt2 )
                return 1;
            else
                return 0;
        }

        public static int Line( RichTextBox e, int index )
        {
             int correction = GetCorrection( e, index );
             return e.GetLineFromCharIndex( index ) - correction + 1;
        }

        public static int Column( RichTextBox e, int index1 )
        {
             int correction = GetCorrection( e, index1 );
             Point p = e.GetPositionFromCharIndex( index1 - correction );

             if ( p.X == 1 )
                 return 1;

             p.X = 0;
             int index2 = e.GetCharIndexFromPosition( p );

             int col = index1 - index2 + 1;

             return col;
         }
    }
}

Displaying line number in RichTextBox for the line number portion.