C#

//*****************************************
//*      Storm.TextBox.Document.Caret     *
//*   Storm.TextBox.dll (c) Vestras 2009  *
//*                                       *
//*    Caret.cs - a class used for        *
//*    displaying a caret for the user.   *
//*                                       *
//* Copyright (c) Theodor Storm 2009      *
//*****************************************

namespace Storm.TextBox.Document
{
    using System;
    using System.Collections.Generic;
    using System.Drawing;
    using System.Linq;
    using System.Text;
    using System.Windows.Forms;

    public class Caret : Control
    {
        #region Members
        // Timer for displaying the caret.
        private Timer caretTimer = new Timer();

        // Timer members.
        private int Interval = 50;

        // Display members.
        private string caretString = "|";
        private Font caretFont = new Font(new Font("Courier New", 9.25f), FontStyle.Bold);
        private Color caretColor = SystemColors.ControlText;
        private bool caretDisplay = true; // The member for showing and hiding the caret
                                          // every Interval miliseconds.

        // Caret position and size members
        private Point caretPos = new Point(-1, -1);
        private Size caretSize;
        #endregion

        #region Properties
        /// <summary>
        /// Gets or sets the font of the caret.
        /// </summary>
        public Font CaretFont
        {
            get { return caretFont; }
            set { caretFont = value; }
        }

        /// <summary>
        /// Gets or sets the string that the caret "contains".
        /// </summary>
        public string DisplayString
        {
            get { return caretString; }
            set { caretString = value; }
        }

        /// <summary>
        /// Gets or sets the interval of the timer that displays the caret.
        /// </summary>
        public int CaretInterval
        {
            get { return Interval; }
            set { Interval = value; }
        }
        #endregion

        #region Methods
        private void onTick(object sender, EventArgs e)
        {
            caretDisplay = !caretDisplay;
            Invalidate();
        }

        private void DrawCaret(Graphics g)
        {
            if (caretDisplay == true)
            {
                Rectangle r = new Rectangle(caretPos, caretSize);
                ControlPaint.DrawStringDisabled(g, caretString, caretFont, caretColor, r, TextFormatFlags.Default);
            }
        }

        private void onPaint(object sender, PaintEventArgs e)
        {
            DrawCaret(e.Graphics);
        }


        #endregion

        /// <summary>
        /// Initialize the caret.
        /// </summary>
        public Caret()
        {
            Paint += new PaintEventHandler(onPaint);

            caretTimer.Enabled = true;
            caretTimer.Tick += new EventHandler(onTick);
            caretTimer.Start();
        }
    }
}

xPixel=(textColumnNumber-horizontalScrollCount)*textCharacterWidth;
yPixel=(textLineNumber-verticalScrollCount)*textLineHeight;

colNum = (Cursor.Position.X + this.stormParent.HorizontalScroll.Value) /  charWidth;<br />
rowNum = (Cursor.Position.Y + this.stormParent.VerticalScroll.Value)   / charHeight;

Vestras wrote:

like this?

Vestras wrote:

wouldn't the textLineHeight be the same as charHeight?

xPixel = (textColumnNumber - horizontalScrollCount) * textCharacterWidth;
yPixel = (textLineNumber - verticalScrollCount) * textLineHeight;
          ______/\______                          ___________/\__________
           Unknown Vars                               Unknown Var(S)?    

colNum = (Cursor.Position.X - this.stormParent.HorizontalScroll.Value) / charWidth - charWidth;
lineNum = (Cursor.Position.Y - this.stormParent.VerticalScroll.Value) / (int)this.Font.Size - (int)this.Font.Size;