bool whetherSelected = false;

        Point pt = new Point();

        private void pbBigImage_MouseDown(object sender, MouseEventArgs e)

        {

            whetherSelected = true;

            pt = Cursor.Position;

            this.Cursor = System.Windows.Forms.Cursors.SizeAll;

        }



        private void pbBigImage_MouseMove(object sender, MouseEventArgs e)

        {

            if (whetherSelected)

            {

                Point newPoint = new Point();

                if (pbBigImage.Width > panel2.Width) 

                {

                    newPoint.X = pbBigImage.Left + Cursor.Position.X - pt.X;

                }

                if (pbBigImage.Height > panel2.Height) 

                {

                    newPoint.Y = pbBigImage.Top + Cursor.Position.Y - pt.Y;

                }

                pbBigImage.Location = newPoint; 

                pt = Cursor.Position;

            }

        }



        private void pbBigImage_MouseUp(object sender, MouseEventArgs e)