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How to set or get the Scroll Position of a RichTextBox Control

To set or get the scroll position of a RichTextBox control we need the help of a little Windows API.
Specifically, we use the SendMessage function to send the EM_GETSCROLLPOS, EM_SETSCROLLPOS messages to the control.
To get the scroll position of a RichTextBox control we use the following GetScrollPos function and to set it we use the following SetScrollPos function.

	
 
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Drawing;
using System.Windows.Forms;

namespace FourDots
{
    class RichTextBoxHelper
    {
        [DllImport("user32.dll")]
        private static extern int SendMessage(IntPtr hwndLock, Int32 wMsg, Int32 wParam, ref Point pt);

        public static Point GetScrollPos(RichTextBox txtbox)
        {
            const int EM_GETSCROLLPOS = 0x0400 + 221;
            Point pt = new Point();

            SendMessage(txtbox.Handle, EM_GETSCROLLPOS, 0, ref pt);
            return pt;
        }

        public static void SetScrollPos(Point pt,RichTextBox txtbox)
        {
            const int EM_SETSCROLLPOS = 0x0400 + 222;

            SendMessage(txtbox.Handle, EM_SETSCROLLPOS, 0, ref pt);
        }        
    }
}


 

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