VC++ sending message between two application

问题

I have been searching to send a message from Microsoft Visual C++ to another application created in Delphi for 2 hours.

In delphi I know how to read the data. But I don't know exactly how to send a message in MVC++

I hope you can get me a code.

So for the next code I want a translation in Microsoft Visual Studio C++ 2010, my project it is a console project.

const 
  MY_MESSAGE = WM_USER + 4242; 

type 
  TForm1 = class(TForm) 
    Button1: TButton; 

procedure Button1Click(Sender: TObject); 

  end; 
var 
  Form1: TForm1; 
implementation 
{$R *.DFM} 

procedure TForm1.Button1Click(Sender: TObject); 
var 
  txt: string; 
begin 
  txt := 'Hello World'; 
  SendMessage(Form1.Handle, MY_MESSAGE, 0, DWORD(PChar(txt))); 
end; 


end.

And with this code I should read the data. Also I want to be compatible.

const 
  MY_MESSAGE = WM_USER + 4242; 

type 
  TForm1 = class(TForm) 

    // Handler that receive the Message 

procedure MessageReceiver(var msg: TMessage); message MY_MESSAGE; 
  end; 
var 
  Form1: TForm1; 
implementation 
{$R *.DFM} 


procedure TForm1.MessageReceiver(var msg: TMessage); 
var 
  txt: PChar; 
begin 
  txt := PChar(msg.lParam); 
  msg.Result := 1; 
  ShowMessage(txt); 
end; 
end.

So my application contains two parts: One in Microsoft Visual Studio, i use opencv and i want to send a message to the second application, which is created in Delphi.

回答1:

I don't know how to use the pipeline, but I have used before the following scheme:

Use WM_COPYDATA message using SendMessage(). Here is a reference

http://msdn.microsoft.com/en-us/library/windows/desktop/ms649011(v=vs.85).aspx

and the example

http://msdn.microsoft.com/en-us/library/windows/desktop/ms649009(v=vs.85).aspx

You will need to use FindWindow to get a handle to the application you want to send the message to.

回答2:

You can use the WM_GETTEXT or WM_COPYDATA message to send buffers of data back and forth between applications. I once searched for a way to send a buffer like WM_GETTEXT does, only with a different message. The original code can be found here:

http://www.nldelphi.com/forum/showthread.php?p=275167#post275167

I don't know if everything still works (haven't used it since), but it did back then.

// The order (first Buffer, then BufferLength) seems more sensible, although with
// WM_SETTEXT they are actually the other way around.
function SendTextMessage(Handle: THandle; Msg: Integer; Buffer: Pointer; BufferLength: Integer): Cardinal;
var
  ProcessHandle: THandle;
  ProcessId: Cardinal;
  VirtualBuffer: Pointer;
begin
  // Get the id of process to which the handle belongs.
  GetWindowThreadProcessID(Handle, @ProcessId);
  ProcessHandle := OpenProcess(PROCESS_ALL_ACCESS, False, ProcessId);

  if ProcessHandle = 0 then
    RaiseLastWin32Error;

  // Allocate a virtual buffer in the process
  VirtualBuffer := VirtualAllocEx(ProcessHandle, nil, BufferLength,
                           MEM_COMMIT, PAGE_READWRITE);
  if VirtualBuffer = nil then
    RaiseLastWin32Error;

  try
    // Send a message to the handle, passing the virtual pointer as a buffer
    Result := SendMessage(Handle, Msg, BufferLength, Integer(VirtualBuffer));

    // Read the resulting value from the virtual buffer into the given buffer
    if not ReadProcessMemory(ProcessHandle, VirtualBuffer, Buffer, Result, Result) then
      RaiseLastWin32Error;

  finally
    VirtualFreeEx(ProcessHandle, VirtualBuffer, BufferLength, MEM_RELEASE);
  end;

end;

And call it like this:

var
  h: THandle;
  b: array[0..1024] of Char;
begin
  h := Cardinal(StrToInt(Edit1.Text));
  // Not like this
  //SendMessage(h, WM_GETTEXT, 1024, Integer(@b));

  // But like this
  SendTextMessage(h, WM_USER+1, @b, 1024 * SizeOf(Char));
  ShowMessage(b);

Read the message like this:

procedure WM_USERPLUS1(var Msg: TWMGetText); message WM_USER+1;


procedure TForm2.WM_USERPLUS1(var Msg: TWMGetText);
begin
  with Msg do
    Result := StrLen(StrLCopy(PChar(Text), PChar('Hallo wereld'), TextMax - 1)) * SizeOf(Char);
end;

It's probably just as easy to use WM_COPYDATA, though. :D

来源：https://stackoverflow.com/questions/10126342/vc-sending-message-between-two-application

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