A Standard for Thumbnailers

Carsten Haitzler (The Rasterman) raster at rasterman.com
Tue Jan 9 07:41:24 PST 2007


On Tue, 09 Jan 2007 12:08:46 +0100 Benedikt Meurer <benny at xfce.org> babbled:

> Stanislav Brabec wrote:
> > - Image files in public directories are thumbnailed many times:
> >   once for each accessing user.
> 
> Sharing thumbnails might be a security problem.
> 
> > - Thumbnails on removable media are thumbnailed many times: once for
> >   each machine, where medium is accessed
> 
> IIRC the standard already covers this, tho it's not implemented in Xfce
> and GNOME.
> 
> > - Thumbnail files are often larger than images itself, especially for
> >   jpeg images below 20kB in size.
> 
> The software can detect this and load the JPEG directly.
> 
> > - There is a very small chance to detect deleted images and delete
> >   corresponding thumbnail.
> 
> The file manager should clean up the thumbnails when deleting files.
> 
> > Use unique inode_number/volume_id instead of file_path.
> 
> This will not work with certain FUSE file systems, that generate unique
> inodes on-demand, because it's likely that the inodes will be different
> each time the file system is mounted.
> 
> > Haw widely used desktop-neutral thumbnailing library understanding many
> > embedded thumbnails and providing thumbnailing for images without
> > embedded thumbnail.
> 
> I think external thumbnailer as used by Thunar/Nautilus are better,
> because it's more flexible and avoids loading various libraries required
> to generate thumbnails for different formats into the processes.
> 
> Using .desktop files to register thumbnailers instead of GConf should be
> fine for desktop-neutral usage.
> 
> > Allow jpeg thumbnails.
> 
> Aside from maybe a few bytes saved per thumbnail, why would you want to
> do this?

it's nto a few bytes. for 128x128 sizes thumbs a thumbnail can go from a 20k
png to a 2k jpeg very very very easily. the jpeg thumbs invariably are
significantly smaller than the png ones (depending on the quality level you are
happy with). over the space of a few thousand thumbnails this make a BIG
difference.

> > Thumbnails can use file system extended attributes.
> 
> Not every file system supports that. What would be stored in the
> extended attributes anyway?
> 
> Benedikt
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-- 
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    raster at rasterman.com
裸好多
Tokyo, Japan (東京 日本)



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