I'll use this kind of code for loading thumbnails. Things going fine about 200 files and less that number of files. But above
that number of files i get this error message: The parameter is incorrect.

    { Public declarations }
   Procedure LoadJpeg;
   Procedure imgOnDblClick(Sender: TObject);

 Img1Width : Integer;
  Img1Height : Integer;
  NewImage : TImage;
  NewShape : TShape;
  NewScrollBox : TScrollBox;
  CurrentFName : String;
  FNameList : TStringList;

Procedure TView.LoadJpeg;
  TheDir : String;
  FMask : String;
  res : word;
  WindFind : TWin32FindData;
  NextSearch : Boolean;
  imgW, imgH, imgL, imgT : Integer;
  imgCount : Integer;
  NewJpegImage : TJpegImage;
  imgJpegList : TStringList;
  NewBitMap : TBitmap;
  tmpLabel : TLabel;
 Screen.Cursor := crHourGlass;
 Shape1.Parent := Panel1;
 If Assigned(NewScrollBox) Then NewScrollBox.Free;
NewScrollBox := TScrollBox.Create(Panel1);
NewScrollBox.Parent := Panel1;
NewScrollBox.Align := alClient;
 tmpLabel := TLabel.Create(NewScrollBox);
 tmpLabel.Parent := NewScrollBox;
 tmpLabel.Caption := '     ';
 tmpLabel.Left := NewScrollBox.Width + 100;
Shape1.Parent := NewScrollBox;
  If Assigned(FNameList) Then FNameList.Free;
 FNameList := TStringList.Create;

  TheDir := DirView1.Path;
If TheDir[Length(TheDir)] <> '\' Then TheDir := TheDir + '\';
 FMask := FilterComboBox1.Mask;
imgW := 105;
imgH := NewScrollBox.Height - GetSystemMetrics(SM_CYHSCROLL) - 6;
imgL := 0;
imgT := 1;
imgJpegList := TStringList.Create;
   NextSearch := True;
    res := Windows.FindFirstFile(PChar(TheDir + FMask), WindFind);
  While NextSearch Do
    If Not ((StrPas(WindFind.cFileName) = '.') Or (StrPas(WindFind.cFileName) = '..')) Then
     If (WindFind.dwFileAttributes  And Not FILE_ATTRIBUTE_DIRECTORY) > 0 Then
      imgJpegList.Add(TheDir + StrPas(WindFind.cFileName));
     NextSearch := FindNextFile(res, WindFind);
If imgJpegList.Count < 1 Then Exit;
  For imgCount := 0 To imgJpegList.Count - 1 Do
    NewJpegImage := TJpegImage.Create;
    NewImage := TImage.Create(NewScrollBox);
    NewBitMap := TBitmap.Create;
    NewImage.Visible := False;
    NewImage.Parent := NewScrollBox;
    NewImage.Left := imgL;
    NewImage.Top := imgT;
    NewImage.Width := imgW;
    NewImage.Height := imgH;
    NewImage.Stretch := True;
    imgL := imgL + imgW + 4;
    NewImage.Visible := True;
    NewImage.OnDblClick := imgOnDblClick;

    Screen.Cursor := crDefault;

Procedure TView.imgOnDblClick(Sender: TObject);
 Shape1.Width := (Sender As TImage).Width + 4;
 Shape1.Height := (Sender As TImage).Height + 2;
 Shape1.Left := (Sender As TImage).Left - 2;
 Shape1.Top := (Sender As TImage).Top - 1;
 Shape1.Visible := True;
  ViewerForm.Image1.Picture := (Sender As TImage).Picture;
  ViewerForm.HorzScrollBar.Range := (Sender As TImage).Picture.Width;
  ViewerForm.VertScrollBar.Range := (Sender As TImage).Picture.Height;
  ViewerForm.Caption := 'Viewer 3.0' + ' - ' +
        Format(' (%d x %d)', [(Sender As TImage).Picture.Width, (Sender As TImage).Picture.Height]);
  ViewerForm.ClientWidth := (Sender As TImage).Picture.Width;
  ViewerForm.ClientHeight := (Sender As TImage).Picture.Height;

procedure TView.SpeedButton8Click(Sender: TObject);
Shape1.Visible := False;
  if FilterComboBox1.Mask = '*.JPG' then
  Panel1.Visible:= True;

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Perhaps you should store the thumbnails in a TImageList instead of using several TImage components. You then would have to use e.g. a TPaintBox and draw the thumbnails at the right position in the TPaintBox.OnPaint event. With such a solution it doesn't matter, if you have 200 or 2000 thumbs...

Regards, Madshi.
mhietaAuthor Commented:
I have not used TImageList yet. What i have to change in above code?. Drawing to the TPaintBox.OnPaint event those thumbnails using TImageList.

Regards mhieta
The TImage component does all for you. You don't need to do anything. But it has resource problems.
The TPaintBox component does nothing. It just calls you, when the content of the paint box needs repainting (and this is the OnPaint event). If you don't do anything in the OnPaint event handler, the paint box simply stays clean/empty/white.
So in TPaintBox.OnPaint you need to draw something. The best choice would be to load all your bitmaps like you do in the sources, but then don't assign the ready thumbnail to TImage.Bitmap, but instead add this bitmap to your image list. Then in OnPaint use the TImageList functions to draw the bitmaps at the right position.
You must do more than with TImage, your sources probably will get a bit longer, but the result is much faster and resource friendlier.

Regards, Madshi.

P.S: Sorry, have no time now to write sources for you...
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Even more Memory Freindly, a DIB and write it so simple and small as possiple, And why 200+ Thumbs at once?

if for generating pics "index pics" with 20x10 Thumbs etc or by showing it to user you could make it more Optimal by only generating and storing those that are visible to user, same way some Games work with large worlds or like 3D Studio Max uses the Material-Browser.

Here is list of Files "Images"
and we "play" that user only can see 3 Thumbs at a time :

bbbbbbb.jpg  (Not Visible but already Generated)
ccccccc.jpg  (Visible)
ddddddd.jpg  (Visible)
eeeeeee.jpg  (Visible)
fffffff.jpg  (Not Visible but already Generated)

Then you only show the c d and e pics and mabye have a and f ready too eg +xx and -xx pics so user can scroll a few realtime and same time u are already generating above and below ..

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mhietaAuthor Commented:
Sometimes user has ex.200 or more or less jpg pics on the folder. So user can scroll those pics, when pics are generated. I know there are so many ways to do that, what i'm trying to do. But your succestion sounds nice also. Is there any sample or source code for that?.

i have no hurry to do that, what i'm trying to do.

Regards mhieta
else there is Several of Thumb VCLS out there.. but my idea should not be needing a sample should it?

you just generate from File user Selected and xx forward and mabye a few backwards.. and display it..
mhietaAuthor Commented:
Hi, brainware

brainware, Ok i have this now done by you suggestion. And it runs perfectly. I modified that code what i showed in question. I think, it's not exactly what you suggested to me. So, it load's now 10 images forward and backwards. But that modification doesn't get rid off that resource problem.
Where i can find these Thumb VCLS?

Regards mhieta
mhietaAuthor Commented:

Ok, thanks brainware for your suggestion...

mhietaAuthor Commented:
And also thanks to you Madshi!!, maybe next time you have some time...

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