Steve, Many thanks for those changes. The program compiles fine, but the API call still returns 0. When I check the result of GetLastError I get the message 'The system call level is not correct'. I am guessing this must be something to do with the level parameter to the AddPortEx function, which determines the type of port structure being passed in lpBuffer (either PPortInfo1 or PPortInfo2).
Can anyone shed any more light on this or recommend a friend who might be able to. Many thanks, Darren -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Steve Williams Sent: 25 May 2005 04:41 To: Borland's Delphi Discussion List Subject: Re: Adding a printer port - at my wits end Darren McBride wrote: > procedure AddPrinterPort(Handle: HWnd; Instance: HInst; CommandLine: > PChar; > ShowWindow: Integer); > var > pl: TStringList; > fn: function(pName: PChar; pLevel: Integer; lpBuffer: Pointer; > pMonitorName: PChar): Integer; > i: Integer; > lh: THandle; > pi: PPortInfo1; > pn: String; > begin > try > { check for valid port name } > if (Trim(CommandLine) = '') then > Exit; > > { check for existing port name } > pl := TStringList.Create; > try > ListPorts(pl); > if (pl.IndexOf(CommandLine) >= 0) then > Exit; > finally > pl.Free; > end; > > { add new port } > lh := LoadLibrary('winspool.drv'); > if (lh >= 32) then > begin > @fn := GetProcAddress(lh, 'AddPortExA'); fn is already a pointer to a function, and GetProcAddress returns a pointer to the function. Remove the '@' to make it fn := GetProcAddress(lh, 'AddPortExA'); > if (@fn <> nil) then Delphi can sometimes get confused when using pointers to functions. Try this. if Assigned(fn) then > begin > GetMem(pi, SizeOf(pi)); You are getting to the size of a pointer here (four bytes). What you need is to dereference the pointer. GetMem(pi, SizeOf(pi^)); > try > ZeroMemory(pi, SizeOf(pi)); Same here. Dereference the pointer to get the size of the type it points to. ZeroMemory(pi, SizeOf(pi^)); > pn := String(CommandLine); > pi^.pName := PChar(pn + #0); > i := fn(nil, 1, @pi, 'Local Port'); Since pi is already a pointer, you do not need to get the address of it. Remove the '@'. i := fn(nil, 1, pi, 'Local Port'); > if (i = 0) then > SysErrorMessage(GetLastError); > finally > FreeMem(pi); > end; > end; > FreeLibrary(lh); > end; > > { handle all errors } > except > on e: Exception do > ShowMessage(e.Message); > end; > end; > > end. > > In the line 'i := fn(nil, 1, @pi, 'Local Port');' I have tried @pi and > pi, as I don't fully understand pointers. -- Sly This message and its attachments may contain legally privileged or confidential information. This message is intended for the use of the individual or entity to which it is addressed. If you are not the addressee indicated in this message, or the employee or agent responsible for delivering the message to the intended recipient, you may not copy or deliver this message or its attachments to anyone. Rather, you should permanently delete this message and its attachments and kindly notify the sender by reply e-mail. Any content of this message and its attachments, which does not relate to the official business of the sending company must be taken not to have been sent or endorsed by the sending company or any of its related entities. No warranty is made that the e-mail or attachment(s) are free from computer virus or other defect. _______________________________________________ Delphi mailing list -> [email protected] http://www.elists.org/mailman/listinfo/delphi
