panel若添加透明背景图，panel上的控件刚显示时太卡

[qq_16031013]

Form背景色为24,28,29，Form上有几个panel，每个panel都有很多控件label和textbox，panel背景色设为透明，当panel没有使用背景图时（即backgroundimage属性为无），所有控件可以一下子显示出来；但当使用透明的背景图片时(设置backgroundimage属性为本地某个透明的PNG图片)，控件就一个接一个慢慢显示出来的，卡的很，请问该如何解决？

[desperaso]

    /// <summary>
    /// 双缓冲 panel
    /// </summary>
    public class PanelEx : Panel
    {
        public PanelEx()
        {
            SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer | ControlStyles.ResizeRedraw | ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
            UpdateStyles();
        }
    }

    /// <summary>
    /// 双缓冲 PictureBox
    /// </summary>
    public class PictureBoxEx : PictureBox
    {
        public PictureBoxEx()
        {
            SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer | ControlStyles.ResizeRedraw | ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
            UpdateStyles();
        }
    }

		/// <summary>
    /// 双缓冲 TreeView
    /// </summary>
    public class TreeViewEx : TreeView
    {
        protected override void OnHandleCreated(EventArgs e)
        {
            SendMessage(this.Handle, TVM_SETEXTENDEDSTYLE, (IntPtr)TVS_EX_DOUBLEBUFFER, (IntPtr)TVS_EX_DOUBLEBUFFER);
            base.OnHandleCreated(e);
        }
        private const int TVM_SETEXTENDEDSTYLE = 0x1100 + 44;
        private const int TVM_GETEXTENDEDSTYLE = 0x1100 + 45;
        private const int TVS_EX_DOUBLEBUFFER = 0x0004;
        [DllImport("user32.dll")]
        private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);
    }

		/// <summary>
    /// 双缓冲 ListView
    /// </summary>
    public class ListViewEx : ListView
    {
        public ListViewEx()
        {
            SetStyle(ControlStyles.DoubleBuffer | ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint, true);
            UpdateStyles();
        }
    }

[qq_16031013]

引用 1 楼 desperaso 的回复:

    /// <summary>
    /// 双缓冲 panel
    /// </summary>
    public class PanelEx : Panel
    {
        public PanelEx()
        {
            SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer | ControlStyles.ResizeRedraw | ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
            UpdateStyles();
        }
    }

    /// <summary>
    /// 双缓冲 PictureBox
    /// </summary>
    public class PictureBoxEx : PictureBox
    {
        public PictureBoxEx()
        {
            SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer | ControlStyles.ResizeRedraw | ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
            UpdateStyles();
        }
    }

		/// <summary>
    /// 双缓冲 TreeView
    /// </summary>
    public class TreeViewEx : TreeView
    {
        protected override void OnHandleCreated(EventArgs e)
        {
            SendMessage(this.Handle, TVM_SETEXTENDEDSTYLE, (IntPtr)TVS_EX_DOUBLEBUFFER, (IntPtr)TVS_EX_DOUBLEBUFFER);
            base.OnHandleCreated(e);
        }
        private const int TVM_SETEXTENDEDSTYLE = 0x1100 + 44;
        private const int TVM_GETEXTENDEDSTYLE = 0x1100 + 45;
        private const int TVS_EX_DOUBLEBUFFER = 0x0004;
        [DllImport("user32.dll")]
        private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);
    }

		/// <summary>
    /// 双缓冲 ListView
    /// </summary>
    public class ListViewEx : ListView
    {
        public ListViewEx()
        {
            SetStyle(ControlStyles.DoubleBuffer | ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint, true);
            UpdateStyles();
        }
    }

请问只要写下面关于panel的就可以了，panel上的控件不用写了吧，是写在Form1.cs中对吧
public class PanelEx : Panel
{
public PanelEx()
{
SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer | ControlStyles.ResizeRedraw | ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
UpdateStyles();
}
}