asked on

EnumPrintProcessors in Delphi

I have studied Microsoft WinDDK and found that if I want to track detail of print job from each client (win98, XP, 2000) then I have two choices to choose
1. Writing print monitor (Language or port monitor)
2. Writing print processor
However writing print monitor in Delphi is a mad process. It has difficulty in translate some header file which is easier in MS VC++. So I choose the PrintProcessor. In all approach I have to study Printer Language like PCL5, PCL5e, PCL6 etc and use information found in RAW data file to count printed page. I begin studying from PrintProcessor Installer program and some related functions. And I have problem in getting result from EnumPrintProcessors API function
in case of there are more than one processor. This is my function:

procedure TForm1.MyEnumPrintProcessors(AServer: string);
var pInfo : Pointer;
cbBuf, pcbNeeded, pcbReturned : Cardinal;
i : integer;
begin
cbBuf := 128;
try
GetMem(pInfo,cbBuf);
if EnumPrintProcessors(PChar(AServer),nil,1,pInfo, cbBuf,pcbNeeded,pcbReturned) then
begin
Memo1.Lines.Add('EnumprintProcessors Succeeded - buffer size needed is '+IntToStr(pcbNeeded));
Memo1.Lines.Add('EnumprintProcessors Succeeded - number of PrintProcessors '+inttostr(pcbReturned));
for i := 1 to pcbReturned do
begin
Memo1.Lines.Add(' Printprocessor #'+IntToStr(i)+' named "'+string(pInfo^));
//Inc(,pcbNeeded);
end;

end
else
Memo1.Lines.Add('Failed');

finally
FreeMem(pInfo);
end;
end;

In my case pcbReturned is 2 which is the number of print processor installed. The problem is how can I get the second string from pInfo pointer.

soapsiam

soapsiam

ASKER

I have tried this form of program it works. Howerver, it has to fix number of array member, Is there anyway better than this? I think 50 point is worth for this solution.

procedure TForm1.MyEnumPrintProcessors(AServer: string);
var
pServerName : PChar;
pInfo : array[1..255] of TPrintProcessorInfo1;
pcbNeeded, pcbReturned : Cardinal;
i : integer;
begin
try
if AServer = '' then
pServerName := nil
else
pServerName := PChar(AServer);
if EnumPrintProcessors(pServerName,nil,1,@pInfo, SizeOf(pInfo),pcbNeeded,pcbReturned) then
begin
Memo1.Lines.Add('EnumprintProcessors Succeeded - buffer size needed is '+IntToStr(pcbNeeded));
Memo1.Lines.Add('EnumprintProcessors Succeeded - number of PrintProcessors '+inttostr(pcbReturned));
for i := 1 to pcbReturned do
begin
Memo1.Lines.Add(' Printprocessor #'+IntToStr(i)+' named "'+string(pInfo[i].pName)+'"');
end;
end
else
Memo1.Lines.Add('Failed');
finally
end;
end;

Ivanov_G

Parametes pInfo :
Points to an ARRAY of PRINTPROCESSOR_INFO_1 structures. One structure is created for each available print processor.

string(pInfo^) - this if what you need, but the address is the address of the first element. The index starts from 0

string(pInfo[1]^) - should be the second one.

soapsiam

ASKER

That is not correct as in Delphi pInfo is Pointer. However in MS SDK it specifies that pInfo points to array of printprocessorinfo1. It may be point to string separated by NULL (#0).
I think I have to check this.

soapsiam

ASKER

I found the solution it is:

unit Main;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, WinSpool, Printers;

type
TForm1 = class(TForm)
Button1: TButton;
Memo1: TMemo;
procedure Button1Click(Sender: TObject);
private
{ Private declarations }
procedure MyEnumPrintProcessors(pServer: PChar);
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

function IncPtr(P:Pointer;Delta:Integer=1):Pointer;register;
asm
add eax, edx
end;

procedure TForm1.MyEnumPrintProcessors(pServer: PChar);
var pInfo : Pointer;
pcbNeeded, pcbReturned : Cardinal;
i : integer;
pProcessInfo : PPrintProcessorInfo1;
begin
EnumPrintProcessors(nil,nil,1,pInfo, 0, pcbNeeded, pcbReturned);
if (GetLastError <> ERROR_INSUFFICIENT_BUFFER) then exit;
Memo1.Lines.Add('EnumprintProcessors Succeeded - buffer size needed is '+IntToStr(pcbNeeded));
GetMem(pInfo, pcbNeeded);
try
if EnumPrintProcessors(nil,nil,1,pInfo, pcbNeeded,pcbNeeded,pcbReturned) then
begin
Memo1.Lines.Add('EnumprintProcessors Succeeded - number of PrintProcessors installed is '+inttostr(pcbReturned));
for i := 0 to pcbReturned-1 do
begin
pProcessInfo := IncPtr(pInfo,i*SizeOf(TPrintProcessorInfo1));
Memo1.Lines.Add(' Printprocessor #'+IntToStr(i)+' named "'+string(pProcessInfo.pName)+'"');
end;
end
else
begin
Memo1.Lines.Add('Failed');
RaiseLastOSError;
end

finally
FreeMem(pInfo);
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
MyEnumPrintProcessors(nil);
end;

end.

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