关于打印机的消息处理

Question

我要做一个打印机管理程序，来记录打印人、打印的份数等情况。
我使用了以下一个消息处理程序来监视打印机的状态，但是在有
打印任务来的时候，它更本没有反应啊，那位高手能解决？
..........
type
  TForm1 = class(TForm)
    StatusBar1: TStatusBar;
    Memo1: TMemo;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    procedure WMSpollerStatus(var Msg:TWMSpoolerStatus); message WM_SPOOLERSTATUS;
    { Private declarations }
  public
    { Public declarations }
  end;.............procedure TForm1.WMSpollerStatus(var Msg: TWMSpoolerStatus);
var
  tbt:Byte;
  Needed,Returned:DWORD;
  ResultBuffer:Pointer;
  i,x,Count:Integer;
  Pi:PJobInfo1;
  List:TListBox;
  Lbl:TLabel;
begin
    Inherited;
    MessageBeep(0);
    EnumJobs(hPrinter,0,Msg.JobsLeft,1,@tbt,0,Needed,Returned);
    Count := Needed;
    GetMem(ResultBuffer,Count);
    try
      EnumJobs(hPrinter,0,Msg.JobsLeft,1,ResultBuffer,Needed,Needed,Returned);
      if Returned < Msg.JobsLeft then
      begin
        //Lbl.Caption:='0 个作业';
        Memo1.Lines.Add('0 个作业');
      //  Continue;
      end;
      //Lbl.Caption:=IntToStr(Returned)+' 个作业';
      Memo1.Lines.Add(IntToStr(Returned)+' 个作业');
      Pi:=ResultBuffer;
      for x:=0 to Returned-1 do begin
        //List.Items.Add(Pi^.pDocument);
        Memo1.Lines.Add(Pi^.pDocument);
        Pi:=PJobInfo1(LongInt(Pi)+Sizeof(Pi^));
      end;
    finally
      FreeMem(ResultBuffer,Count);
    end;  Msg.Result:=0;
end;.............

Answer 1

完整代码如下，建立一个窗体，在上面放一个MEMO和BUTTON
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ComCtrls, StdCtrls,WinSpool,ExtCtrls;type
  TForm1 = class(TForm)
    StatusBar1: TStatusBar;
    Memo1: TMemo;
    Button1: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    procedure WMSpollerStatus(var Msg:TWMSpoolerStatus); message WM_SPOOLERSTATUS;
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;
  hPrinter:THandle;implementation{$R *.dfm}{ TForm1 }procedure TForm1.WMSpollerStatus(var Msg: TWMSpoolerStatus);
var
  tbt:Byte;
  Needed,Returned:DWORD;
  ResultBuffer:Pointer;
  i,x,Count:Integer;
  Pi:PJobInfo1;
  List:TListBox;
  Lbl:TLabel;
begin
    MessageBeep();
    EnumJobs(hPrinter,0,Msg.JobsLeft,1,@tbt,0,Needed,Returned);
    Count := Needed;
    GetMem(ResultBuffer,Count);
    try
      EnumJobs(hPrinter,0,Msg.JobsLeft,1,ResultBuffer,Needed,Needed,Returned);
      if Returned < Msg.JobsLeft then
      begin
        //Lbl.Caption:='0 个作业';
        Memo1.Lines.Add('0 个作业');
      //  Continue;
      end;
      //Lbl.Caption:=IntToStr(Returned)+' 个作业';
      Memo1.Lines.Add(IntToStr(Returned)+' 个作业');
      Pi:=ResultBuffer;
      for x:=0 to Returned-1 do begin
        //List.Items.Add(Pi^.pDocument);
        Memo1.Lines.Add(Pi^.pDocument);
        Pi:=PJobInfo1(LongInt(Pi)+Sizeof(Pi^));
      end;
    finally
      FreeMem(ResultBuffer,Count);
    end;  Msg.Result:=0;
end;
procedure TForm1.FormCreate(Sender: TObject);
var
  tbt:Byte;
  Needed,Returned:DWORD;
  ResultBuffer:Pointer;
  x,Count:Integer;
  Pi:PPrinterInfo1;
  Sheet:TTabSheet;
//  hPrinter:THandle;
  Panel:TPanel;
  PrinterName : string;
begin
//  PrinterLst.Clear;
  EnumPrinters(PRINTER_ENUM_LOCAL,'',1,@tbt,0,Needed,Returned);
  if Needed=0 then Exit;
  Count:=Needed;
  GetMem(ResultBuffer,Count);
  EnumPrinters(PRINTER_ENUM_LOCAL,'',1,ResultBuffer,Needed,Needed,Returned);
  Pi:=ResultBuffer;
  for x:=0 to Returned-1 do begin
//    PrinterLst.Items.Add(Pi^.pName);
    memo1.Lines.Add(Pi^.pName);
    PrinterName:=Pi^.pName;
    OpenPrinter(PChar(PrinterName),hPrinter,nil);    Pi:=PPrinterInfo1(LongInt(Pi)+Sizeof(Pi^));
    {
    Sheet:=TTabSheet.Create(Self);
    with Sheet do begin
      PageControl:=Pages;
      Caption:=PrinterLst.Items[PrinterLst.Items.Count-1];
      OpenPrinter(PChar(Caption),hPrinter,nil);
      Tag:=hPrinter;
      ClosePrinter(hPrinter);
      with TListBox.Create(Self) do begin
        Parent:=Sheet;
        Align:=alClient;
      end;
      Panel:=TPanel.Create(Self);
      with Panel do begin
        Parent:=Sheet;
        Align:=alTop;
        Height:=20;
        BevelOuter:=bvNone;
      end;
      with TLabel.Create(Self) do begin
        Parent:=Panel;
        Left:=10;
        Top:=3;
        Caption:='0 个作业';
      end;
 
    end;
}
  end;
  FreeMem(ResultBuffer,Count);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
Print();
end;end.