C#图片放大.

private bool isMoving = false;

        private int x, y;





        private void mouseDown(object sender, MouseEventArgs e)

        {

            this.pictureBox1.Focus();

            isMoving = true;

            x = e.X;

            y = e.Y;

        }



        private void mouseMove(object sender, MouseEventArgs e)

        {

            if (isMoving)

            {

                this.pictureBox1.Left += (e.X - x);

                this.pictureBox1.Top += (e.Y - y);



            }

        }



        private void mouseUp(object sender, MouseEventArgs e)

        {

            isMoving = false;

        }



        private void PictureBox1_MouseWheel(object sender, System.Windows.Forms.MouseEventArgs e)

        {



            if (e.Delta > 0)

            {

                pictureBox1.Width = Convert.ToInt32(pictureBox1.Width * 0.8);

                pictureBox1.Height = Convert.ToInt32(pictureBox1.Height * 0.8);



            }



            else

            {

                pictureBox1.Width = Convert.ToInt32(pictureBox1.Width / 0.8);

                pictureBox1.Height = Convert.ToInt32(pictureBox1.Height / 0.8);



            }



        }

小弟现在这个放大代码,充其量只是能放大图片所在的PICTRUEBOX来达到放大图片的结果,但是放大的效果不好,图片是在PICTRUEBOX的左上角开始放大,那么就会造成图片会"走动"可否有办法放大的效果是"居中放大".请高手帮帮忙
------解决方案--------------------
写在代码里最直接，根据原始图片的 Width 和 pictureBox1.Width 进行判断