PikView has a sophisticated image thumbnail management system which allows the user to quickly locate images. Files currently loaded into the selector can be viewed in thumbnail mode by selecting Thumbnails from the View menu. If PikView has previously made thumbnails for these images they will load rapidly from the cache. Any images which have not been previously rendered as thumbnails will be created and saved in a database as long as the thumbnail option "Use cache" is selected. Any images which have been modified will also be updated. You may still use the image viewer while the thumbnails are being created.
By default PikView stores its thumbnail database in a file called ~/.pikview.gtn. This is file used when no other can be found. One problem with this system is that files must be stored by their absolute path names (say /home/ajr/pics/test.jpg). This means that if the directory "pics" is renamed to "images" all the thumbnails become invalid. In order to solve this problem PikView allows thumbnail files inside image directories. This means the user could make a file /home/ajr/pics/pikview.tn which would hold the thumbnail information. Now renaming the directory would no longer invalidate the thumbnails. Furthermore, thumbnail files in directories hold thumbnail information for all subordinate directories unless those sub-directories have thumbnails files themselves. This means that you can have a single thumbnail file at an important level (say the root of a CDROM) and thus avoid a proliferation of thumbnail files.
As JPEG is a very common image format some efforts have been made to enhance the speed at which image thumbnails are created for this format. Thumbnails for this format are created significantly faster than for other formats.
The following thumbnail commands are available from the Thumbnails menu.
Creates a thumbnail file in the directory currently selected in the directory pane. Users may create their own thumbnail databases by creating and empty file called pikview.tn in the relevant directory.
Removes a thumbnail file.
Equivalent to deleting and re-creating.
Finds the thumbnail file which serves this directory, deletes thumbnails for images which have been deleted or moved and finally packs the thumbnail database to save space.
First packs the thumbnail file as above (removing deleted items etc) and then creates thumbnails for the current directory and any sub-directories. This may take some time during which PikView is usuable.
Various command line options deal with the maintainence and generation of thumbnail files from the command line. This way the user can build thumbnail databases in the background and without having to visit each directory individually. There are no options to create or delete thumbnail databases from the command line as these operations can be accompilished by using the shell commands "rm pikview.tn" and "touch pikview.tn" respectively. The diffenence between the --build-thumbs and --rebuild-thumbs options is that --build-thumbs does not pack the database, check existing entries or delete out of date entries.