thumbnail spec + .thumblocal additions/clarifications

[Stanislav Brabec]

David Zeuthen wrote:

> 
> Second, I'd like to patch the spec with some additions for .thumblocal
> support; here's a copy of the latest that the Wayback machine could give
> me
> 

I'd like to see more changes there:


Problem: Depending on the OS and medium details, thumbnail of external
media files may be drive # specific. (e. g. thumbnail
for /mnt/cdrom0/image.png != thumbnail for /mnt/cdrom0/image.png).

Proposal: Replace path relevant to changeable media by any type of UUID.


Problem: Symlinked files, files in symlinked directories and hardlinked
files are thumbnailed once per path, not once per file. (e. g. thumbnail
for ~/Desktop/myphoto_link/01.jpg != thumbnail for
~/Images/myphoto/01.jpg).

Possible solutions:
- Use inode for systems that support it.
- Expand path to not contain symlinks.
- Use xargs note to refer to thumbnail for systems that support it.


Problem: Images in shared directories are thumbnailed once per user
accessing it.

Possible solutions:
- Use thumblocal if possible.
- Use system overlay in globally accessible directory.
- Use xargs and re-use thumbnail of another user.


Problem: Thumbnail of small jpeg images are typically larger in size and
slower to load than downloading and downscaling of original image.

Proposal: Allow jpeg thumbnails.


Problem: Many modern file formats include thmubnails (JPEG+EXIF, RAW
+EXIF,...)

Proposal:
- Don't create thumbnail, reuse embedded thumbnail.
- Use xargs for note about thumbnail. If not possible, use
notes .thumblocal or .thumbnails.


Problem: Thumbnailing has to be implemented separately for each project.

Solution:
- Exact description of thumbnails interface
- Reference thumbnailing implementation


Problem: Proposal is not rename/remove friendly. Each file rename keeps
orphaned thumbnail.

Ugly solution:
- Each application must be aware of thumbnail handlinkg while rename or
  remove file.


All above mentioned problems in summary cause, that some images on the
disc may be thumbnailed many times, with many possible file names from
4-dimensional matrix:

once after downloading, once after final rename
 x
once for ~/Images path access, once for access through desktop symlink
 x
once for nautilus, once for gqview (large size)
 x
once for each user

-- 
Best Regards / S pozdravem,

Stanislav Brabec
software developer
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