二、导出的基本过程

System.Drawing.Imaging.Metafile mf;
Graphics g1 = control.CreateGraphics();
IntPtr hdc = g1.GetHdc();
mf = new Metafile(hdc, new Rectangle(0, 0, control.Width, control.Height), MetafileFrameUnit.Pixel, EmfType.EmfOnly);
g1.ReleaseHdc(hdc);
g1.Dispose();

const int WM_PRINT = 0x0317;

const int PRF_CHECKVISIBLE = 0x00000001,
PRF_NONCLIENT = 0x00000002,
PRF_CLIENT = 0x00000004,
PRF_ERASEBKGND = 0x00000008,
PRF_CHILDREN = 0x00000010;
[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr SendMessage(HandleRef hWnd, int msg, int wParam, int lParam);

public static void DrawControl(Control control, Graphics g)
{
    if (!control.Created)
         control.CreateControl();

    IntPtr hDc = g.GetHdc();
    SendMessage(new HandleRef(control, control.Handle), WM_PRINT, (int)hDc,(int)(PRF_CHILDREN | PRF_CLIENT | PRF_ERASEBKGND | PRF_NONCLIENT));
    g.ReleaseHdc(hDc);
}

        [DllImport("user32.dll")]
        static extern bool OpenClipboard(IntPtr hWndNewOwner);
        [DllImport("user32.dll")]
        static extern bool EmptyClipboard();
        [DllImport("user32.dll")]
        static extern IntPtr SetClipboardData(uint uFormat, IntPtr hMem);
        [DllImport("user32.dll")]
        static extern bool CloseClipboard();
        [DllImport("gdi32.dll")]
        static extern IntPtr CopyEnhMetaFile(IntPtr hemfSrc, IntPtr hNULL);
        [DllImport("gdi32.dll")]
        static extern bool DeleteEnhMetaFile(IntPtr hemf);

        static public bool PutEnhMetafileOnClipboard(IntPtr hWnd, Metafile mf)
        {
            bool bResult = false;
            IntPtr hEMF, hEMF2;
            hEMF = mf.GetHenhmetafile(); // invalidates mf 
            if (!hEMF.Equals(new IntPtr(0)))
            {
                hEMF2 = CopyEnhMetaFile(hEMF, new IntPtr(0));
                if (!hEMF2.Equals(new IntPtr(0)))
                {
                    if (OpenClipboard(hWnd))
                    {
                        if (EmptyClipboard())
                        {
                            IntPtr hRes = SetClipboardData(14 /*CF_ENHMETAFILE*/, hEMF2);
                            bResult = hRes.Equals(hEMF2);
                            CloseClipboard();
                        }
                    }
                } DeleteEnhMetaFile(hEMF);
            } return bResult;
        }