A Tiny Parser Generator v1.2

// Copyright 2008 - 2010 Herre Kuijpers - <herre.kuijpers@gmail.com>
//
// This source file(s) may be redistributed, altered and customized
// by any means PROVIDING the authors name and all copyright
// notices remain intact.
// THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED. USE IT AT YOUR OWN RISK. THE AUTHOR ACCEPTS NO
// LIABILITY FOR ANY DATA DAMAGE/LOSS THAT THIS PRODUCT MAY CAUSE.
//-----------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Drawing2D;

namespace TinyPG.Controls
{
    /// <summary>
    /// the text marker is responsible for underlining erronious text (= marked words) with a wavy line
    /// the text marker also handles the display of the tooltip
    /// </summary>
    public class TextMarker : NativeWindow, IDisposable
    {
        public RichTextBox Textbox;
        private List<Word> MarkedWords;
        private ToolTip ToolTip;
        private bool toolTipVisible;
        private Point lastMousePos;

        private struct Word
        {
            public int Start;
            public int Length;
            public Color Color;
            public string ToolTip;
        }

        public TextMarker(RichTextBox textbox)
        {
            Textbox = textbox;
            Textbox.MouseMove += new MouseEventHandler(Textbox_MouseMove);
            this.AssignHandle(Textbox.Handle);
            ToolTip = new ToolTip();
            toolTipVisible = false;
            Clear();
            lastMousePos = new Point();
        }

        void Textbox_MouseMove(object sender, MouseEventArgs e)
        {
            if (lastMousePos.X == e.X || lastMousePos.Y == e.Y)
                return;

            lastMousePos = new Point(e.X, e.Y);
            int i = Textbox.GetCharIndexFromPosition(lastMousePos);

            bool found = false;
            foreach (Word w in MarkedWords)
            {
                if (w.Start <= i && w.Start + w.Length > i)
                {
                    Point p = Textbox.GetPositionFromCharIndex(w.Start);
                    p.Y += 18;

                    ToolTip.Show(w.ToolTip, (IWin32Window)Textbox, p);
                    found = true;
                    toolTipVisible = true;
                }
            }

            if (!found) 
            {
                ToolTip.Hide((IWin32Window)Textbox);
                toolTipVisible = false;
            }
        }

        protected override void WndProc(ref Message m)
        {
            // pre-process the text control's messages
            switch (m.Msg)
            {
                case 0x14: // WM_ERASEBKGND
                    base.WndProc(ref m);
                    MarkWords();
                    break;
                case 0x114: // WM_HSCROLL
                    base.WndProc(ref m);
                    MarkWords();
                    break;
                case 0x115: // WM_VSCROLL
                    base.WndProc(ref m);
                    MarkWords();
                    break;
                case 0x0101: // WM_KEYUP
                    base.WndProc(ref m);
                    MarkWords();
                    break;
                case 0x113: // WM_TIMER
                    base.WndProc(ref m);
                    MarkWords();
                    break;
                default:
                    //Console.WriteLine(m.Msg);
                    base.WndProc(ref m);
                    break;
            }
        }
        
        public void AddWord(int wordstart, int wordlen, Color color)
        {
            AddWord(wordstart, wordlen, color, "");
        }
        
        public void AddWord(int wordstart, int wordlen, Color color, string ToolTip)
        {
            Word word = new Word();
            word.Start = wordstart;
            word.Length = wordlen;
            word.Color = color;
            word.ToolTip = ToolTip;
            MarkedWords.Add(word);
        }

        public void Clear()
        {
            MarkedWords = new List<Word>();
        }

        public void MarkWords()
        {
            if (Textbox.IsDisposed || !Textbox.Enabled || !Textbox.Visible) return;

            Graphics graphics = Textbox.CreateGraphics();

            int minpos = Textbox.GetCharIndexFromPosition(new Point(0, 0));
            int maxpos = Textbox.GetCharIndexFromPosition(new Point(Textbox.Width, Textbox.Height));
            foreach (Word w in MarkedWords)
            {
                // check if the marked word is currently displayed on screen
                if (w.Start + w.Length < minpos || w.Start > maxpos) 
                    continue;

                MarkWord(w, graphics);
            }
            graphics.Dispose();
        }

        private void MarkWord(Word word, Graphics graphics)
        {
            GraphicsPath path = new GraphicsPath();

            List<Point> points = new List<Point>();
            Point p1 = Textbox.GetPositionFromCharIndex(word.Start);
            Point p2 = Textbox.GetPositionFromCharIndex(word.Start + word.Length);

            if (word.Length == 0)
            {
                p1.X -= 5;
                p2.X += 5;
            }

            p1.Y += Textbox.Font.Height - 2;
            points.Add(p1);
            bool up = true;
            for (int x = p1.X + 2; x < p2.X + 2; x += 2)
            {
                Point p = up ? new Point(x, p1.Y + 2) : new Point(x, p1.Y);
                points.Add(p);
                up = !up;
            }
            if (points.Count > 1)
            {
                path.StartFigure();
                path.AddLines(points.ToArray());
            }

            Pen pen = new Pen(word.Color);
            graphics.DrawPath(pen, path);
            pen.Dispose();
            path.Dispose();
        }
        
        #region IDisposable Members

        public void Dispose()
        {
            this.ReleaseHandle();
        }

        #endregion
    }
}