使用OpenDialog出现“句柄无效”

lightdc4 2013-11-19 03:05:58

因为要频繁地打开文件保存到数据库，所以用久了就会突然显示“句柄无效”，这是什么情况？

procedure Button1Click(Sender: TObject);

var

 i : integer;

begin



  OpenDialogFilter := '*.jpg|*.jpg';

  OpenDialogFileName := '';

  OpenDialogExecute;



  if OpenDialogFiles.Count = 0 then

    exit;



  with aqrecordphotos do

  begin

    for i := 0 to OpenDialogFiles.Count - 1 do

    begin

      append;

        tblobField(findfield('Photo')).LoadFromFile(OpenDialogFiles.Strings[i]);

        tblobField(findfield('smallphoto')).LoadFromStream(ZoomJpgFrmFile(OpenDialogFiles.Strings[i]));

      post;

    end;

  end;



end;



function ZoomJpgFrmFile(vFileName: String): TStream;

var

  Jpg : TJpegImage;

  Bmp : TBitmap;

const

  SPercent  : single = 0.1;

begin



  jpg := TJpegImage.Create;

  Bmp := TBitmap.Create;



  jpg.loadfromfile(vfilename);



  bmp := jpg2bmp(jpg);

  if bmp.Width * SPercent <= 100 then

    bmp := zoombmp(bmp,100,trunc(100 / bmp.Width * bmp.Height))

  else

    bmp := zoombmp(bmp,trunc(bmp.Width * spercent),trunc(bmp.Height * spercent));

  jpg := bmp2jpg(bmp,100);



  result := TMemoryStream.Create;

  jpg.SaveToStream(result);

  jpg.free;

  bmp.Free;



end;



function Jpg2Bmp(Jpg: TJpegImage): TBitmap;

begin



  Result   :=   nil;

  if   Assigned(Jpg) then

  begin

    Result   :=   TBitmap.Create;

    Jpg.DIBNeeded;   {Key   method...}

    Result.Assign(Jpg);   {It‖s   all   folks...}

  end;



end;



function ZoomBmp(vImage: TBitmap; dWidth,

  dHeight: Integer): TBitmap;

var

  ori:   TBitmap;

  dispositivo_o,   dispositivo_d:   HDC;

  pepito:   HBitmap;

begin



  ori   :=   Tbitmap.Create;

  result   :=   TBItmap.Create;

  ori.handle   :=   vImage.handle;

  result.width   :=   dWidth;

  result.height   :=   dHeight;

  dispositivo_o   :=   CreateCompatibleDC(0);

  dispositivo_d   :=   CreateCompatibleDC(0);

  SelectObject(dispositivo_o,   ori.handle);

  pepito   :=   SelectObject(dispositivo_d,   result.handle);

  SetStretchBltMode(dispositivo_d,     STRETCH_HALFTONE);

  StretchBlt(dispositivo_d,   0,   0,   dWidth,   dHeight,   dispositivo_o,   0,   0,   ori.width,   ori.height,   SRCCOPY);

  SelectObject(dispositivo_d,   pepito);

  ori.Free;

  DeleteObject(pepito);

  DeleteDC(dispositivo_o);

  DeleteDC(dispositivo_d);



end;



function Bmp2Jpg(Bmp: TBitmap; Quality: Integer): TJpegImage;

begin



  Result   :=   nil;

  if   Assigned(Bmp)  then

  begin

    Result   :=   TJpegImage.Create;

    Result.Assign(Bmp);   {It‖s   all   folks...}

    Result.CompressionQuality   :=   Quality;

    Result.JPEGNeeded;   {Key   method...}

    Result.Compress;

  end;



end;