{
This is useful if you want to send a message from your DLL back
to the calling application.
}
const
MY_MESSAGE = WM_USER + 4242;
type
TForm1 = class(TForm)
Button1: TButton;
procedure Button1Click(Sender: TObject);
// Handler that receive the Message
procedure MessageReceiver(var msg: TMessage); message MY_MESSAGE;
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;
// To receive this custom Message that is addressed to form1.handle
// you need a message handler.
procedure TForm1.MessageReceiver(var msg: TMessage);
var
txt: PChar;
begin
txt := PChar(msg.lParam);
msg.Result := 1;
ShowMessage(txt);
end;
end.