C#鼠標滾輪處理滾動條滾動

 //鼠標進入控件的可見部分
        private void PictureBox_MouseEnter(object sender, EventArgs e)
        {
            this.Focus();
        }

 //處理鼠標滾輪//當e.Delta > 0時鼠標滾輪是向上滾動，e.Delta < 0時鼠標滾輪向下滾動。
        protected override void OnMouseWheel(System.Windows.Forms.MouseEventArgs e)
        {
            if (e.Delta > 0)
            {

               if ((vScrollBar1.Value - 10) < vScrollBar1.Minimum)
                {
                    vScrollBar1.Value = vScrollBar1.Minimum;
                }
                else

                 {
                    vScrollBar1.Value -=10;
                }
            }
            else

            {
                if ((vScrollBar1.Value+10) > vScrollBar1.Maximum)
                {
                    vScrollBar1.Value = vScrollBar1.Maximum;
                }

               else
                {
                    vScrollBar1.Value += 10;
                }
            }

     }