WM_COPYDATA

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3 total messages Started by Ray Sat, 20 Jan 2007 17:28

#116

Author: Ray
Date: Sat, 20 Jan 2007 17:28

67 lines
2776 bytes

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);
 }

Re: WM_COPYDATA

#117

Author: Marc Rohloff TeamB
Date: Sat, 20 Jan 2007 19:31

40 lines
2339 bytes

On Sat, 20 Jan 2007 17:28:43 -0000, Ray wrote:

> 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.

> cds.cbData = Marshal.SizeOf(cds.dwData);
This should be
 cds.cbData = Marshal.SizeOf(sendData);

A simpler way to call SendMessage would be:

public class Win32
{
   [DllImport("user32.dll", CharSet=CharSet.Ansi)]
   public static extern int SendMessage(
                                   HandleRef hWnd, 
                                   int msg, 
                                   IntPtr wParam, 
                                   [In, Out,                    
                                    MarshalAs(UnmanagedType.LPStruct)] 
                                   CopyDataStruct lParam);
 
   [StructLayout(LayoutKind.Sequential, Pack=4)]
   public struct CopyDataStruct
   {
     public int dwData;
     public int cbData;
     public IntPtr data;
   }

This way you can just pass a CopyDataStruct into SendMessage without
having to worry about Marshalling it.
  

-- 
Marc Rohloff [TeamB]
marc rohloff -at- myrealbox -dot- com

Re: WM_COPYDATA

#118

Author: Ray
Date: Sun, 21 Jan 2007 13:16

46 lines
2251 bytes

Many thanks all working fine now

Ray
"Marc Rohloff [TeamB]" <"on request"> wrote in message 
news:80n5rkq4zz6p.dlg@dlg.marcrohloff.com...
> On Sat, 20 Jan 2007 17:28:43 -0000, Ray wrote:
>
>> 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.
>
>> cds.cbData = Marshal.SizeOf(cds.dwData);
> This should be
> cds.cbData = Marshal.SizeOf(sendData);
>
> A simpler way to call SendMessage would be:
>
> public class Win32
> {
>   [DllImport("user32.dll", CharSet=CharSet.Ansi)]
>   public static extern int SendMessage(
>                                   HandleRef hWnd,
>                                   int msg,
>                                   IntPtr wParam,
>                                   [In, Out,
>                                    MarshalAs(UnmanagedType.LPStruct)]
>                                   CopyDataStruct lParam);
>
>   [StructLayout(LayoutKind.Sequential, Pack=4)]
>   public struct CopyDataStruct
>   {
>     public int dwData;
>     public int cbData;
>     public IntPtr data;
>   }
>
> This way you can just pass a CopyDataStruct into SendMessage without
> having to worry about Marshalling it.
>
>
> -- 
> Marc Rohloff [TeamB]
> marc rohloff -at- myrealbox -dot- com

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