🚀 go-pugleaf

Hi

I am trying to use WM_COPYDATA to send data between applications. I can send 
one integer successfully but if I try to send more than one the second is 
garbage.

If I try to send an integer array it crashes with a message that my array is 
not blittable. I understood that integer arrays as distinct from Array types 
were blittable. So I am definitely missing something here.

My code is as follows
Declarations (common to both sender and receiver)

public class Win32
{
  [DllImport("user32.dll", CharSet=CharSet.Ansi)]
  public static extern int SendMessage(uint hWnd, int msg, IntPtr wParam, 
IntPtr lParam);
  [StructLayout(LayoutKind.Sequential)]
  public class CopyDataStruct
  {
    public int dwData;
    public int cbData;
    public IntPtr data;
  }
  [StructLayout(LayoutKind.Sequential)]
  public class DataArray
  {
      public int num1;
      public int num2;
  }
}

Sender code

Win32.DataArray sentData = new Win32.DataArray();
sentData.num1=7101;
sentData.num2=8102;
IntPtr numMemory = 
Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Win32.DataArray)));
Marshal.StructureToPtr(sentData, numMemory, false);
Win32.CopyDataStruct cds=new Win32.CopyDataStruct();
cds.dwData = 101;
cds.cbData = Marshal.SizeOf(cds.dwData);
cds.data = numMemory;

IntPtr cdsMemory = 
Marshal.AllocHGlobal(Marshal.SizeOf(typeof(Win32.CopyDataStruct)));
Marshal.StructureToPtr(cds, cdsMemory, false);
Win32.SendMessage(recHandle,(int)msg,IntPtr.Zero, cdsMemory);
Marshal.FreeHGlobal(cdsMemory);
Marshal.FreeHGlobal(numMemory);

Receiver code

unsafe protected override void WndProc(ref Message m)
{
  if(m.Msg==msg)
  {
    Win32.CopyDataStruct cds=new Win32.CopyDataStruct();
    Win32.DataArray recData= new Win32.DataArray();
    Marshal.PtrToStructure((IntPtr)m.LParam.ToPointer(), cds);
    Marshal.PtrToStructure(cds.data,recData);
    // read recData.num1 and recData.num2
   }
   base.WndProc(ref m);
 }