asked on

C# to Delphi WM_COPYDATA

Hi

I'm trying to pass some small data from C# to Delphi and have decided to try to make it work with WM_COPYDATA. I have a C# code that does pass message to Delphi and Delphi that receives it, but I have problem with the message format, content.
I send
from C# : "Test message"
and I get in Delphi: #1#0#0#0'T'...

See screenshot of sText value in Delphi:

I'm sure I'm very close, but don't know where I'm failing.

Here is C# code:

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Security;

 class Program
    {
        public const int WM_COPYDATA = 0x004A;
        [return: MarshalAs(UnmanagedType.Bool)]

		[DllImport("user32.dll")]
        public static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

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

		[System.Runtime.InteropServices.DllImport("user32.dll",CharSet = CharSet.Auto)]
        public static extern IntPtr SendMessage(IntPtr hwnd, int msg,IntPtr wparam, IntPtr lparam);

		[DllImport("user32.dll", EntryPoint = "FindWindow")]
        public static extern IntPtr FindWindowByCaption(IntPtr ZeroOnly, string lpWindowName);
        
		[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
        public struct MyStruct
        {
            public int Number;

            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
            public string Message;
        }
		
		
        public static IntPtr IntPtrAlloc<T>(T param)
        {
            IntPtr retval = Marshal.AllocHGlobal(Marshal.SizeOf(param));
            Marshal.StructureToPtr(param, retval, false);
            return (retval);
        }
 
        public static void IntPtrFree(IntPtr preAllocated)
        {
            if (IntPtr.Zero == preAllocated) throw (new Exception("Go Home"));
            Marshal.FreeHGlobal(preAllocated); preAllocated = IntPtr.Zero;
        }
 
		
		[StructLayout(LayoutKind.Sequential)]
        public struct COPYDATASTRUCT
        {
            public IntPtr dwData;       // Specifies data to be passed
            public int cbData;          // Specifies the data size in bytes
            public IntPtr lpData;       // Pointer to data to be passed
        }
		
		[SuppressUnmanagedCodeSecurity]
        public class NativeMethod
        {
            [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
            public static extern IntPtr SendMessage(IntPtr hWnd, int Msg,
                IntPtr wParam, ref COPYDATASTRUCT lParam);


            [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
            public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
        }
	

		
    }

public static class MyCalss
{
	public static System.String MyFunc()
	{
		
		
			// Find the target window handle.
            IntPtr hTargetWnd = Program.NativeMethod.FindWindow(null, "ReceiverMainForm");
            if (hTargetWnd == IntPtr.Zero)
            {
                MessageBox.Show("Unable to find the \"ReceiverMainForm\" window", 
                    "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
		
	
			// Prepare the COPYDATASTRUCT struct with the data to be sent.
            Program.MyStruct myStruct;
			myStruct.Number = 1;
            myStruct.Message = "Test message";
			myStruct.Message = myStruct.Message;
		
		    // Marshal the managed struct to a native block of memory.
            int myStructSize = Marshal.SizeOf(myStruct)+1;
            IntPtr pMyStruct = Marshal.AllocHGlobal(myStructSize);
            try
            {
                Marshal.StructureToPtr(myStruct, pMyStruct, true);

                Program.COPYDATASTRUCT cds = new Program.COPYDATASTRUCT();
                cds.dwData = (IntPtr)1;
				cds.cbData = myStructSize;
				
                cds.lpData = pMyStruct;

				 MessageBox.Show("myStructSize"+(int)myStructSize, 
                    "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
				
				Program.NativeMethod.SendMessage(hTargetWnd, Program.WM_COPYDATA, IntPtr.Zero, ref cds);

                int result = Marshal.GetLastWin32Error();
                if (result != 0)
                {
                    MessageBox.Show(String.Format(
                        "SendMessage(WM_COPYDATA) failed w/err 0x{0:X}", result));
                }
            }
            finally
            {
                Marshal.FreeHGlobal(pMyStruct);
            }		
		
	return "done";
	}

}

Open in new window

And Delphi:

procedure TForm1.WMCOPYDATA(var Msg: TWMCopyData);
var
  sText: String;
begin
  Msg.Result:=0;
        if Msg.CopyDataStruct.cbData>0 then
        begin
          SetLength(sText, Msg.CopyDataStruct.cbData);
          CopyMemory(PChar(sText), Msg.CopyDataStruct.lpData, Msg.CopyDataStruct.cbData);
          Msg.Result:=1;
        end;
  ShowMessage(sText);
end;

Open in new window

Any help would be appreciated!

Thank you!

SOLUTION

David Johnson, CD

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

SOLUTION

chaau

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

MerijnB

What delphi version are you using?

Delphi_developer

ASKER

I use Delphi 2006. What is easiest to convert for future expansion.. convert to Ansi in C# or in Delphi?

MerijnB

If you are planning to migrate Delphi to a unicode version (2007 and above) it's easiest on Delphi side, otherwise you should do it on C# side.

Delphi_developer

ASKER

I'm planning to migrate to XE7/8, but not for months and I need solution now.
I'm new to C# and even though I tried to figure out what to do, from user chaau suggestion, I don't know how to do it, Since nobody posted a suggestion, yet, I assume is not a simple convert function...

ASKER CERTIFIED SOLUTION

Sinisa Vuk

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Delphi_developer

ASKER

Thank you, Sinisa, it works!
I changed Delphi to:

s:=Pchar(msg.CopyDataStruct.lpData);
Number := msg.CopyDataStruct.dwData;
ShowMessage('Msg: ' + s + ' Number: ' + IntToStr(Number));

Open in new window

And it seems to be working without text limit, I sent 8.000 characters and it works like a charm! :)

I will make a note for XExx versions.

Now it works, I just hope I don't get to any surprises when using it.

Just a quick sub question:
Is this structure fixed (dwData,cbData and lpData)?
All examples I found online are the same structure. So, I can send 1 Number and 1 Text. Or is it possible to set custom structure, like 10x Number and 10 x Text?

The question is because, ideally, I would like to send more data... and it this case I would just include everything in a single text:
'PARAM_NAMES=Param1;Param2;param3;Param4;Param5...;PARAM_VALUES=Value1;Value2;Value3;Value4;Value5;...' - to pass 5 parameters (name and value).

It is possible with different structure, but don't know where to go.

Thank you!

Sinisa Vuk

There is two ways as I can see. One is to use record/structure as you do before - but same must be implemented in revers order in Delphi. Second is to use aka xml text which you can send as you do now.

text to send:
<IPCText><Param1>12</Param1><Param2>5</Param2><Text1></Text1></IPCText>
... with crlf+tabs if you like. Use some parser and voilà...

SOLUTION

MerijnB

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

Delphi_developer

ASKER

Thank you, very much appreciated the solution and all the comments!