scrollbar_test

 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Windows.Forms;
 using ESRI.ArcGIS.Geometry;
 using ESRI.ArcGIS.Controls;
 using System.Runtime.InteropServices;
 using ESRI.ArcGIS.Display;

 namespace WindowsFormsApplication2
 {
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
         }

         double xmin, ymin, xmax, ymax;
         double Xmin, Ymin, Xmax, Ymax;
         int Xvalue = ;
         int Yvalue = ;
         int Xlarge = ;
         int Ylarge = ;
         double heightFullenv, h, widthFullEnv, w;
         double initScale = 0d;
         int vscrollMaxium = ;
         int hscrollMaxium = ;

         IEnvelope pEnvMap = null;
         IMapControl2 pMapControl = null;
         private void axMapControl1_OnExtentUpdated(object sender, ESRI.ArcGIS.Controls.IMapControlEvents2_OnExtentUpdatedEvent e)
         {
             pEnvMap = e.newEnvelope as IEnvelope;
             pMapControl = axMapControl1.Object as IMapControl2;
             if(initScale < )
                 initScale = pMapControl.MapScale;

             xmin = pEnvMap.XMin;
             ymin = pEnvMap.YMin;
             xmax = pEnvMap.XMax;
             ymax = pEnvMap.YMax;
             w = pEnvMap.Width;
             h = pEnvMap.Height;
             lblLeftBottom.Text = Math.Round(pEnvMap.XMin,).ToString() + "," + Math.Round(pEnvMap.YMin,).ToString();
             lblRightTop.Text = Math.Round(pEnvMap.XMax, ).ToString() + "," + Math.Round(pEnvMap.YMax, ).ToString();
             lblw.Text = pEnvMap.Width.ToString();

             IEnvelope pEnvFull = pMapControl.ActiveView.FullExtent as IEnvelope;
             Xmin = pEnvFull.XMin;
             Ymin = pEnvFull.YMin;
             Xmax = pEnvFull.XMax;
             Ymax = pEnvFull.YMax;
             widthFullEnv = pEnvFull.Width;
             heightFullenv = pEnvFull.Height;
             lblLeftBottomFull.Text = Math.Round(pEnvFull.XMin, ).ToString() + "," + Math.Round(pEnvFull.YMin, ).ToString();
             lblRightTopFull.Text = Math.Round(pEnvFull.XMax, ).ToString() + "," + Math.Round(pEnvFull.YMax, ).ToString();
             lblWf.Text = pEnvFull.Width.ToString();

             if (Ymax > ymax && ymin > Ymin)
             {
                 vscrollMaxium = (int)(heightFullenv / );
                 Yvalue = (int)( (Ymax - ymax) / );
                 Ylarge = (int)(h / );
                 if (Yvalue + Ylarge > vscrollMaxium)
                 {
                     Yvalue = vscrollMaxium - Ylarge;
                 }
             }
             else if (ymax > Ymax)
             {
                 vscrollMaxium = (int)((ymax - Ymin) / );
                 Yvalue = ;
                 Ylarge = (int)(h / );
             }
             else if (Ymin > ymin)
             {
                 vscrollMaxium = (int)((Ymax - ymin) / );
                 Ylarge = (int)(h / );
                 Yvalue = vscrollMaxium - Ylarge + ;
             }
             this.vScrollBar1.Maximum = vscrollMaxium;
             this.vScrollBar1.LargeChange = Ylarge;
             this.vScrollBar1.Value = Yvalue;
             this.vScrollBar1.SmallChange = (int)( * (initScale / pMapControl.MapScale));

             if (Xmax > xmax && xmin > Xmin)
             {
                 hscrollMaxium = (int)(widthFullEnv / );
                 Xvalue = (int)((xmin - Xmin) / );
                 Xlarge = (int)(w / );
                 if (Xvalue + Xlarge > hscrollMaxium)
                 {
                     Xvalue = hscrollMaxium - Xlarge;
                 }
             }
             else if (xmax > Xmax)
             {
                 hscrollMaxium = (int)((xmax - Xmin) / );
                 Xlarge = (int)(w / );
                 Xvalue = hscrollMaxium - Xlarge + ;
             }
             else if (Xmin > xmin)
             {
                 hscrollMaxium = (int)((Xmax - xmin) / );
                 Xvalue = ;
                 Xlarge = (int)(w / );
             }
             this.hScrollBar1.Maximum = hscrollMaxium;
             this.hScrollBar1.LargeChange = Xlarge;
             this.hScrollBar1.Value = Xvalue;
             this.hScrollBar1.SmallChange = (int)( * (initScale / pMapControl.MapScale));

             lblYscroll.Text = "Large:" + Ylarge.ToString() + ",Value:" + Yvalue.ToString() +
                 ",Small:" + vScrollBar1.SmallChange.ToString() + ",Max:" + vScrollBar1.Maximum.ToString();
         }

         private void btnSetDemo_Click(object sender, EventArgs e)
         {
             int max = ;
             int value = ;
             int smallchange = ;
             int largechange = ;
             int.TryParse(this.txtSmallChange.Text, out smallchange);
             int.TryParse(this.txtMaxinum.Text, out max);
             int.TryParse(this.txtValue.Text, out value);
             int.TryParse(txtLargeChange.Text, out largechange);
             this.vScrollBar3.Maximum = max;
             this.vScrollBar3.SmallChange = smallchange;
             this.vScrollBar3.LargeChange = largechange;
             this.vScrollBar3.Value = value;
         }

         private void vScrollBar1_Scroll(object sender, ScrollEventArgs e)
         {
             this.axMapControl1.OnExtentUpdated -= this.axMapControl1_OnExtentUpdated;
             double newheight = (e.OldValue - e.NewValue) * ;
             pEnvMap.Offset(, newheight);
             this.pMapControl.Extent = pEnvMap;
             this.axMapControl1.OnExtentUpdated += this.axMapControl1_OnExtentUpdated;
         }

         private void hScrollBar1_Scroll(object sender, ScrollEventArgs e)
         {
             this.axMapControl1.OnExtentUpdated -= this.axMapControl1_OnExtentUpdated;
             double w = (e.NewValue - e.OldValue) * ;
             pEnvMap.Offset(w, );
             this.pMapControl.Extent = pEnvMap;
             this.axMapControl1.OnExtentUpdated += this.axMapControl1_OnExtentUpdated;
         }

     }
 }

backup_code