在一些票据打印程序中，常常需要动态调整打印机纸张的设置，而网上能够找到的dll只能在98下修改自定义纸张，在nt以上版本中还无相应的dll。所以自己动手通过一些比较笨的办法实现动态修改纸张设置的功能。

{ Important note about DLL memory management: ShareMem must be the
  first unit in your library's USES clause AND your project's (select
  Project-View Source) USES clause if your DLL exports any procedures or
  functions that pass strings as parameters or function results. This
  applies to all strings passed to and from your DLL--even those that
  are nested in records and classes. ShareMem is the interface unit to
  the BORLNDMM.DLL shared memory manager, which must be deployed along
  with your DLL. To avoid using BORLNDMM.DLL, pass string information
  using PChar or ShortString parameters. }

uses
  SysUtils,
  WinSpool,
  Windows,
  Messages,
  Classes;
var
  hPrinter: THandle;

{$R *.res}
Function GetDefaultPrinterName():PChar; //得到默认的打印机名称
var
  sIniFile, sSection, sKeyName,p,q: PChar;
begin
  sIniFile := 'win.ini';
  sSection := 'windows';
  sKeyName := 'device';
  p:=StrAlloc(80);
  q:=StrAlloc(80);
  GetPrivateProfileString(sSection,sKeyName,nil,p,80,sIniFile); 
  StrLCopy(q,p,(strscan(p,',')-p));
  Result := q;
end;

Function addpage():Boolean; //添加一打印纸张类型名称为300k
var
  FormInfo: TFormInfo1;
  PaperSize: TSize;
  PaperRect: TRect;
begin
  FormInfo.Flags := FORM_USER;
  FormInfo.pName := PChar('300k');
  PaperSize.cx := 100000;
  PaperSize.cy := 100000; //300k纸张的默认大小 1000mm*1000mm
  PaperRect.Left := 1;
  PaperRect.Top := 1;
  PaperRect.Right := 100000;
  PaperRect.Bottom := 100000; //纸张的边距
  FormInfo.Size := PaperSize;
  FormInfo.ImageableArea := PaperRect;
  AddForm(hPrinter, 1, @FormInfo);
  Result := True;
end;

Function changepape():Boolean; //改变当前的打印纸张设置
var
  FormInfos : Array [1..1024] of Form_Info_1;
  cbNeeded, cReturned ,neededsize: DWORD;
  i,j:integer;
  ppo:PRINTER_INFO_2;
  dev :PDeviceMode;
begin
  EnumForms(hPrinter, 1, Nil, 0, cbNeeded, cReturned);
  EnumForms(hPrinter, 1, @FormInfos, cbNeeded, cbNeeded, cReturned );
  j := 0;
  for i:= 1 to cReturned  do 通过轮寻找到300k的纸张的纸张类型排序号
    if FormInfos[i].pName = '300k' then j:=i;
  if j=0 then 
  begin
    addpage();
    j := cReturned + 1;
  end; //如无300k纸张则添加
  GetPrinter(hPrinter,2,Nil, 0, @NeededSize);
  GetPrinter(hPrinter, 2, @ppo, NeededSize, @NeededSize);
  dev := ppo.pDevMode;
  dev.dmPaperSize := j;
  ppo.pDevMode := dev;
  SetPrinter(hPrinter,2,@ppo,0); //定义打印机列表并选择300k纸张
  Result := True;
end;

Function MySetPrtInfo(P:Pchar;W:Integer;L:Integer):Boolean;stdcall;
 //设置打印机的纸张类型为300k，并动态修改300k的大小和边距
var
  FormInfo: TFormInfo1;
  PaperSize: TSize;
  PaperRect: TRect;
begin
  OpenPrinter(GetDefaultPrinterName, hPrinter, nil);
  changepape(); //改变纸张类型定义
  FormInfo.Flags := FORM_USER;
  FormInfo.pName := '300K';
  PaperSize.cx := W*100;
  PaperSize.cy := L*100;
  PaperRect.Left := 0;
  PaperRect.Top := 0;
  PaperRect.Right := W*100;
  PaperRect.Bottom := L*100;
  FormInfo.Size := PaperSize;
  FormInfo.ImageableArea := PaperRect;
  SetForm(hPrinter,'300k',1,@FormInfo); //设置纸张大小
  ClosePrinter(hPrinter);
  Result := True;
end;

exports
  MySetPrtInfo;
begin
end.