Select area in PictureBox

Hi Experts,

Here is my UserControl:

/* Title:
 * PictureBox with zoom and scroll functionallity
 */

#region Usings

using System;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Windows.Forms;

#endregion

namespace PictureBoxCtrl
{
      /// <summary>
      /// Summary for the PictureBox Ctrl
      /// </summary>
      public class PictureBox : System.Windows.Forms.UserControl
      {
            #region Members

            public System.Windows.Forms.PictureBox PicBox;
            private System.Windows.Forms.Panel OuterPanel;
            private System.ComponentModel.Container components = null;
            private string m_sPicName = "";

        private bool down;
        private Point start;
        private Rectangle selection = Rectangle.Empty;

            #endregion

            #region Constants

            private double ZOOMFACTOR = 1.25;      // = 25% smaller or larger
            private int MINMAX = 5;                        // 5 times bigger or smaller than the ctrl

            #endregion

            #region Designer generated code

            private void InitializeComponent()
            {
                  this.PicBox = new System.Windows.Forms.PictureBox();
                  this.OuterPanel = new System.Windows.Forms.Panel();
                  this.OuterPanel.SuspendLayout();
                  this.SuspendLayout();
                  //
                  // PicBox
                  //
                  this.PicBox.Location = new System.Drawing.Point(0, 0);
                  this.PicBox.Name = "PicBox";
                  this.PicBox.Size = new System.Drawing.Size(150, 140);
                  this.PicBox.TabIndex = 3;
                  this.PicBox.TabStop = false;
                  //
                  // OuterPanel
                  //
                  this.OuterPanel.AutoScroll = true;
                  this.OuterPanel.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
                  this.OuterPanel.Controls.Add(this.PicBox);
                  this.OuterPanel.Dock = System.Windows.Forms.DockStyle.Fill;
                  this.OuterPanel.Location = new System.Drawing.Point(0, 0);
                  this.OuterPanel.Name = "OuterPanel";
                  this.OuterPanel.Size = new System.Drawing.Size(210, 190);
                  this.OuterPanel.TabIndex = 4;
                  //
                  // PictureBox
                  //
                  this.Controls.Add(this.OuterPanel);
                  this.Name = "PictureBox";
                  this.Size = new System.Drawing.Size(210, 190);
                  this.OuterPanel.ResumeLayout(false);
                  this.ResumeLayout(false);

            }
            #endregion

            #region Constructors

            public PictureBox()
            {
                  InitializeComponent ();
                  InitCtrl ();      // my special settings for the ctrl
            }

            #endregion

            #region Properties

            /// <summary>
            /// Property to select the picture which is displayed in the picturebox. If the
            /// file doesn´t exist or we receive an exception, the picturebox displays
            /// a red cross.
            /// </summary>
            /// <value>Complete filename of the picture, including path information</value>
            /// <remarks>Supported fileformat: *.gif, *.tif, *.jpg, *.bmp</remarks>
            [ Browsable ( false ) ]
            public string Picture
            {
                  get { return m_sPicName; }
                  set
                  {
                        if ( null != value )
                        {
                              if ( System.IO.File.Exists ( value ) )
                              {
                                    try
                                    {
                                          PicBox.Image = Image.FromFile ( value );
                                          m_sPicName = value;
                                    }
                                    catch ( OutOfMemoryException ex )
                                    {
                                          RedCross ();
                                    }
                              }
                              else
                              {                        
                                    RedCross ();
                              }
                        }
                  }
            }

            /// <summary>
            /// Set the frametype of the picturbox
            /// </summary>
            [ Browsable ( false ) ]
            public BorderStyle Border
            {
                  get { return OuterPanel.BorderStyle; }
                  set { OuterPanel.BorderStyle = value; }
            }

        public Rectangle Selection
        {
            get { return selection; }
        }
      

            #endregion

            #region Other Methods

            /// <summary>
            /// Special settings for the picturebox ctrl
            /// </summary>
            private void InitCtrl ()
            {
                  PicBox.SizeMode = PictureBoxSizeMode.StretchImage;
            PicBox.Location = new Point ( 0, 0 );
            PicBox.SizeMode = PictureBoxSizeMode.AutoSize;
                  OuterPanel.Dock = DockStyle.Fill;
                  //OuterPanel.Cursor = System.Windows.Forms.Cursors.NoMove2D;
                  OuterPanel.AutoScroll = true;
                  OuterPanel.MouseEnter += new EventHandler(PicBox_MouseEnter);
                  PicBox.MouseEnter += new EventHandler(PicBox_MouseEnter);
                  OuterPanel.MouseWheel += new MouseEventHandler(PicBox_MouseWheel);
            PicBox.MouseDown += new MouseEventHandler(PicBox_MouseDown);
            PicBox.MouseMove += new MouseEventHandler(PicBox_MouseMove);
            PicBox.MouseUp += new MouseEventHandler(PicBox_MouseUp);
            }

        void PicBox_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                WindowsApplicationPlayer.NativeWIN32.InvalidateRect(IntPtr.Zero, IntPtr.Zero, true);
                //ControlPaint.DrawReversibleFrame(selection, this.BackColor, FrameStyle.Dashed);
                down = true;
                selection = Rectangle.Empty;
                ControlPaint.DrawReversibleFrame(selection, this.BackColor, FrameStyle.Dashed);
                start = this.PointToScreen(new Point(e.X, e.Y));
            }
        }

        void PicBox_MouseMove(object sender, MouseEventArgs e)
        {
            if (down)
            {
                ControlPaint.DrawReversibleFrame(selection, this.BackColor, FrameStyle.Dashed);

                Point end = this.PointToScreen(new Point(e.X, e.Y));
                selection = new Rectangle(start.X, start.Y, end.X - start.X, end.Y - start.Y);

                ControlPaint.DrawReversibleFrame(selection, this.BackColor, FrameStyle.Dashed);
            }
        }

        void PicBox_MouseUp(object sender, MouseEventArgs e)
        {
            if (down)
            {
                //ControlPaint.DrawReversibleFrame(selection, this.BackColor, FrameStyle.Dashed);
                down = false;
            }
        }
            /// <summary>
            /// Create a simple red cross as a bitmap and display it in the picturebox
            /// </summary>
            private void RedCross ()
            {
                  Bitmap bmp = new Bitmap ( OuterPanel.Width, OuterPanel.Height, System.Drawing.Imaging.PixelFormat.Format16bppRgb555 );
                  Graphics gr;
                  gr = Graphics.FromImage ( bmp );
                  Pen pencil = new Pen ( Color.Red, 5 );
                  gr.DrawLine ( pencil, 0, 0, OuterPanel.Width, OuterPanel.Height );
                  gr.DrawLine ( pencil, 0, OuterPanel.Height, OuterPanel.Width, 0  );
                  PicBox.Image = bmp;
                  gr.Dispose ();
            }

            #endregion

            #region Zooming Methods

            /// <summary>
            /// Make the PictureBox dimensions larger to effect the Zoom.
            /// </summary>
            /// <remarks>Maximum 5 times bigger</remarks>
            private void ZoomIn()
            {
            if ( ( PicBox.Width < ( MINMAX * OuterPanel.Width ) ) &&
                        ( PicBox.Height < ( MINMAX * OuterPanel.Height ) ) )
                  {
                        PicBox.Width = Convert.ToInt32 ( PicBox.Width * ZOOMFACTOR );
                        PicBox.Height = Convert.ToInt32 ( PicBox.Height * ZOOMFACTOR );
                        PicBox.SizeMode = PictureBoxSizeMode.StretchImage;
                  }
            }

            /// <summary>
            /// Make the PictureBox dimensions smaller to effect the Zoom.
            /// </summary>
            /// <remarks>Minimum 5 times smaller</remarks>
            private void ZoomOut()
            {
            if ( ( PicBox.Width > ( OuterPanel.Width / MINMAX ) ) &&
                        ( PicBox.Height > ( OuterPanel.Height / MINMAX ) ) )
                  {
                        PicBox.SizeMode = PictureBoxSizeMode.StretchImage;
                        PicBox.Width = Convert.ToInt32 ( PicBox.Width / ZOOMFACTOR );
                        PicBox.Height = Convert.ToInt32 ( PicBox.Height / ZOOMFACTOR );
                  }            
            }

            #endregion

            #region Mouse events

            /// <summary>
            /// We use the mousewheel to zoom the picture in or out
            /// </summary>
            /// <param name="sender"></param>
            /// <param name="e"></param>
            private void PicBox_MouseWheel(object sender, MouseEventArgs e)
            {
            //ControlPaint.DrawReversibleFrame(selection, this.BackColor, FrameStyle.Dashed);
            //if ( e.Delta < 0 )
            //{
            //    ZoomIn ();
            //}
            //else
            //{
            //    ZoomOut ();
            //}
            }

            /// <summary>
            /// Make sure that the PicBox have the focus, otherwise it doesn´t receive
            /// mousewheel events !.
            /// </summary>
            /// <param name="sender"></param>
            /// <param name="e"></param>
            private void PicBox_MouseEnter(object sender, EventArgs e)
            {
                  if ( PicBox.Focused == false )
                  {
                        PicBox.Focus ();
                  }
            }

            #endregion

            #region Disposing

            /// <summary>
            /// </summary>
            protected override void Dispose( bool disposing )
            {
                  if( disposing )
                  {
                        if( components != null )
                              components.Dispose();
                  }
                  base.Dispose( disposing );
            }

            #endregion
      }
}

The problem is when I select an area of my image:
if I don't use the scrollbars, the rectangle is correctly drawn.
if I move scrollbars up or down, then the rectangle is drawn to a wrong location (often outside of the picture and very far from the mouse).

Thanks in advance for your help.