JPEG Thumbnails

[robrichardson]

Help!!! Whilst I have some hair left to pull out!!

Part of a program I am writing allows the user view the contents of a folder as JPEG thumnails. I am using a filtercombobox, a directorylistbox and a filelistbox to navigate and list the files (JPEGs only). If there are JPEGs present then I would like the program to display them as thumbnails on a Tab Page on the same form. There can be variable number of JPEGs in the directory.

Please help - I'm getting desperate!!

 

[2ffat]

How are you trying to show the thumbnails? I know that JPEG's require a little more work to view than BMP. You might want to go to

http://www.bcbdev.com

where they have an article on how to use a JPEG library with BCB.
James P. Cottingham

http://www.ivcusa.com

 

[robrichardson]

It doesn't really matter how the JPEG is displayed, ideally the contents of the filelistbox will be displayed next to each other as small thumbnails (say 5cm x 5xm) on a tab page. I have had a look at your link and I am still none the wiser. I already know how to assign a JPEG to an image control, the problems I have is that I don't neccesarily know how many JPEGs there will be in each directory, so I guess I have to create the image components at runtime. Or do I use one large canvas and draw each image into a new position on the canvas. I really don't know which approach to take as obviously memory handling is important. Any suggestions would be helpful.

 

[2ffat]

Could you do a count on the directory searched and find out how may files with *.JPG there are? You could use the FindFirst, FindNext functions. Once you have that number, can you create the number of cells needed at runtime?
James P. Cottingham

http://www.ivcusa.com

 

[robrichardson]

I've managed to work out how many JPEGs there are. The problem I have is the "cells", what do I use for cells and how do I create them at runtime?

 

[2ffat]

I'm not familar with how to display a JPEG image so I don't know what component you are using. I've seen examples on how to create thumbnails of BMP graphics but not JPEGs. What component would you use to display a single JPEG?

Have you thought of showing a list of the JPEG names in a list box, then when the user highlights the name, the picture is displayed on screen? It might not be as useful as a thumbnail, though.

One place to visit is

http://www.thebits.org/components/pictures.html

and look at the source code for JPEG Explorer. It might have some hints. It uses COM to produce its graphics.
James P. Cottingham

http://www.ivcusa.com

 

[robrichardson]

TJPEGImage *JImage = new TJPEGImage;
JImage->LoadFromFile(FileListBox1->FileName.c_str());

Image1->Width = JImage->Width;
Image1->Height = JImage->Height;
Image1->Picture->Assign(JImage);
Image1->Stretch = true;
delete JImage;

I am using the above code to load a single JPEG. I have looked at the JPEG explorer and its all in delphi.