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
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