communicate between applications?

Author: Igor Siticov

Homepage: http://www.sicomponents.com

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{

You can perform communication between your application using Windows messages

exchange mechanism. We can use HWND_BROADCAST value for first parameter for

SendMessage function for suppressing finding of forms' in other applications HANDLE.

For using HWND_BROADCAST we should register our messages in Windows.

In example below we will inform about our form's top position)

Das Beispiel zeigt, wie zwischen zwei Applikationen eine Meldung (Message)

verschickt werden kann. Die Meldung mit wird mit SendMessage verschickt.

Der erst Parameter ist HWND_BROADCAST, beim zweite ist unsere Message.

Das untenstehende Beispiel informiert z.B über die Top-Position unserer Form}

// 1. Define type of your message structure, it could be something like this:

// 1. Definiere eine eigene Message Struktur:

type

TWMMYMessage = record

Msg: Cardinal; // ( first is the message ID )

Handle: HWND; // ( this is the wParam, Handle of sender)

Info: Longint; // ( this is lParam, pointer to our data)

Result: Longint;

end;

// 2. Override your form's DefaultHandler method and add

// method for handling your message, like this

// 2. Die DefaultHandler Methode zu überschreiben

TForm1 = class(TForm)

...public

{ Public declarations }

...procedure DefaultHandler(var Message); override;

procedure WMMYMessage(var Msg: TWMMYMessage);

...end;

// 3. Declare message variable:

// 3. Die Message-Variablen deklarieren:

var

WM_OURMESSAGE: DWORD;

// 4. Insert realisation of DefaultHandler and our message handler methods:

// 4. DefaultHandler Implementation:

procedure TForm1.DefaultHandler(var Message);

var

ee: TWMMYMessage;

begin

with TMessage(Message) do

begin

if (Msg = WM_OURMESSAGE) then

begin

ee.Msg := Msg;

ee.Handle := wParam;

ee.Info := lParam;

// Checking if this message is not from us

if ee.Handle <> Handle then

WMMYMessage(ee);

end

else

inherited DefaultHandler(Message);

end;

end;

procedure TForm1.WMMYMessage(var Msg: TWMMYMessage);

begin

label1.Caption := Format('Our another form handle :%d', [Msg.Handle]);

Label2.Caption := Format('Our another form top :%d', [Msg.Info]);

end;

// 5. Add registration of your message that you could

// handle the HWND_BROADCAST messages:

// 5. Die Message registrieren.

initialization

WM_OURMESSAGE := RegisterWindowMessage('Our broadcast message');

// 6. Add the message sending somewhere:

procedure TForm1.Button1Click(Sender: TObject);

begin

SendMessage(HWND_BROADCAST, WM_OURMESSAGE, Handle, Top);

end;

// 7. Compile and run two copies of your application and test it functionality.

// 7. Complilieren und zwei Kopien der Applikationen ausführen.