//返回文件数目
    function GetFileCount:integer;

    //设置索引
    procedure SetIndex(AIndex:integer);

    //返回文件索引
    function GetIndex:integer;

    //返回当前完整文件名
    function GetCurFullFileName:string;

    //返回当前文件名
    function GetCurFileName:string;

    //返回下一个文件的文件名
    function GetNextFileName:string;

    //返回上一个文件的文件名
    function GetPreFileName:string;

    constructor Create;
    destructor Destroy;override;
    { Public declarations }
  end;
　

procedure JpgToBmp(const JpgFileName:string;AJpg:TJpegImage;Abmp:Tbitmap);
function  IsJpgFile(const FileName:string):boolean;

  const
  RaisedPanel=1;
  LoweredPanel=2;

var
  Form1: TForm1;
  ImageFileList:TImageFileList;
implementation
  ..

  2.  TImageFileList类具体实现如下：

--------------------------------------------------------------------------------

procedure TImageFileList.Add(FullFileName: string);
begin
  FStrListFile.Add(FullFileName);
end;

--------------------------------------------------------------------------------

procedure TImageFileList.ChangeDir(dir: string);
var
  SearchRec : TSearchRec;
  Attr : integer;
  Found : integer;
  ExtFileName:string;
  temstr:string;

begin
  clear;
  temstr:=dir+''\*.*'';
  Attr := faAnyFile;
  Found := FindFirst(temstr, Attr, SearchRec);
  while Found = 0 do
  begin
    ExtFileName:=LowerCase(ExtractFileExt(SearchRec.Name));
    if (ExtFileName=''.bmp'') or (ExtFileName=''.jpg'') or ((ExtFileName=''.jpeg'')) then
      Add(dir+''\''+SearchRec.Name);

    Found := FindNext(SearchRec);
  end;
  FindClose(SearchRec);
end;

--------------------------------------------------------------------------------

procedure TImageFileList.Clear;
begin
  FStrListFile.Clear;
  Findex:=-1;
end;

constructor TImageFileList.Create;
begin
  FStrListFile:=TStringList.Create;
  Findex:=-1;
end;

destructor TImageFileList.Destroy;
begin
  FStrListFile.Free;
  inherited;
end;

--------------------------------------------------------------------------------

function TImageFileList.GetCurFileName: string;
begin
  result:=ExtractFileName(FStrListFile.Strings[Findex]);
end;

--------------------------------------------------------------------------------

function TImageFileList.GetCurFullFileName: string;
begin
  result:=FStrListFile.Strings[Findex];
end;

--------------------------------------------------------------------------------

function TImageFileList.GetFileCount: integer;
begin
  result:=FStrListFile.Count;
end;

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