Delphi判断一个文件是不是JPG图片

Delphi判断一个文件是不是JPG图片文件

function IsJpegFile(FileName: string): Boolean; const RightBuf : array[0..3] of Byte = ($FF,$D8,$FF,$D9); var Buf: array[0..3] of Byte; begin FillChar(Buf, 4, 0); with TFileStream.Create(FileName, 0) do begin     Position := 0;     ReadBuffer(Buf[0], 2);     Position := Size-2;     ReadBuffer(Buf[2], 2);     Free; end; Result := CompareMem(@RightBuf[0], @Buf[0], 4); end; procedure TForm1.Button1Click(Sender: TObject);//测试 begin if Self.OpenDialog1.Execute then     if IsJpegFile(Self.OpenDialog1.FileName) then       Showmessage('Is Jpg File'); end;