c# autocad 通过进程向cad发送command

主要的过程，日后操作autocad lt也应该可以用此方法

var pros = Process.GetProcessesByName("acad");
            if (pros.Length == 0)
            {
                MessageBox.Show("没有找到acad进程，请检查后再运行本程序！");
                return;
            }
            SendCommandToAutoCAD("_circle 0,0,0 300 ", pros.First().MainWindowHandle);
            SetForegroundWindow(pros.First().MainWindowHandle);

导入win32的api的函数

　　　　　[DllImport("user32.dll")]
        public static extern bool SetForegroundWindow(IntPtr hWnd);

        [DllImport("user32.dll", EntryPoint = "FindWindow")]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("user32.dll")]
        private static extern IntPtr SendMessageW(IntPtr hWnd, int Msg, IntPtr wParam, ref COPYDATASTRUCT lParam);

 private struct COPYDATASTRUCT
        {
            public IntPtr dwData;

            public int cbData;

            public IntPtr lpData;

        }

kean大神提供的向autocad 命令行发送命令的函数

private void SendCommandToAutoCAD(string toSend, IntPtr hwnd)
        {
            const int WM_COPYDATA = 0x4A;
            COPYDATASTRUCT cds = new COPYDATASTRUCT();
            cds.dwData = new IntPtr(1);
            string data = toSend + "";
            cds.cbData = data.Length * Marshal.SystemDefaultCharSize;
            cds.lpData = Marshal.StringToCoTaskMemAuto(data);
            SendMessageW(hwnd, WM_COPYDATA, IntPtr.Zero, ref cds);
            Marshal.FreeCoTaskMem(cds.lpData);
        }