CaptureBitmapFromControl.cs

private Bitmap CaptureControl(Control control)
{
    Bitmap controlBmp;
    using (var g1 = control.CreateGraphics())
    {
        controlBmp = new Bitmap(control.Width, control.Height, g1);
        using (var g2 = Graphics.FromImage(controlBmp))
        {
            var dc1 = g1.GetHdc();
            var dc2 = g2.GetHdc();
            BitBlt(dc2, 0, 0, control.Width, control.Height, dc1, 0, 0, 13369376);
            g1.ReleaseHdc(dc1);
            g2.ReleaseHdc(dc2);
        }
    }

    return controlBmp;
}

[DllImportAttribute("gdi32.dll")]
private static extern bool BitBlt(IntPtr hdcDest, int nXDest, int nYDest, int nWidth,
    int nHeight, IntPtr hdcSrc, int nXSrc, int nYSrc, int dwRop);