C#中找不到MouseWheel事件的解决办法

在.....Designer.cs中加入

            this.pictureBox1.MouseWheel += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseWheel); 

再加入事件

 void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {   double scale = ;
            if (pictureBox1.Height > )
            {
                scale = (double)pictureBox1.Width / (double)pictureBox1.Height;
            }
            pictureBox1.Width += (int)(e.Delta * scale);
            pictureBox1.Height += e.Delta;
        }