public partial class Formdonghua : Form
    {
        //动画窗体调用,关闭时将向上移出屏幕
        [System.Runtime.InteropServices.DllImport("user32")]
        private static extern bool AnimateWindow(IntPtr hwnd, int dwTime, int dwFlags);
        const int AW_HOR_POSITIVE = 0x0001;
        const int AW_HOR_NEGATIVE = 0x0002;
        const int AW_VER_POSITIVE = 0x0004;
        const int AW_VER_NEGATIVE = 0x0008;
        const int AW_CENTER = 0x0010;
        const int AW_HIDE = 0x10000;
        const int AW_ACTIVATE = 0x20000;
        const int AW_SLIDE = 0x40000;
        const int AW_BLEND = 0x80000;
        //…………………………………………………………
        public Formdonghua()
        {
            InitializeComponent();
        }

        private void Formdonghua_Load(object sender, EventArgs e)
        {
            //动画由小渐大,现在取消
            AnimateWindow(this.Handle, 1000, AW_CENTER | AW_ACTIVATE);

            //主界面渐变设置
            this.jianbian.Enabled = true;//让jianbian的timer值有效
            this.Opacity = 0;
            //………………………………………………
        }

        private void jianbian_Tick(object sender, EventArgs e)
        {
            //让背景由0变到1
            if (this.Opacity < 1)
            {
                this.Opacity = this.Opacity + 0.05;
            }
            else
            {
                this.jianbian.Enabled = false;
            }
        }

        private void Formdonghua_FormClosing(object sender, FormClosingEventArgs e)
        {//关闭时动画
            AnimateWindow(this.Handle, 1000, AW_SLIDE | AW_HIDE | AW_VER_NEGATIVE);
        }
    }