[Thunar-dev] Thumbnails

[Benedikt Meurer]

Been thinking about how to do the thumbnailing stuff lately. With the 
current icon loading/caching and the file/folder code, we have a file 
manager that loads large directories faster than any other file manager 
I've installed on my system, where "load" means that the folder is 
completely loaded and displayed. The MIME stuff currently adds the most 
slow-down (and some oddities in the treeview layouting code). But from a 
rather inaccurate benchmark (from warm cache), Thunar loads 
/usr/local/bin (1150 items) faster than ROX, Nautilus, Konqueror or 
Xffm. The folder contains mostly binaries (surprise, surprise), where 
the MIME code has to read the files to determine their type, which is 
pretty slow with the currently imported xdgmime code in libexo. Now that 
test wasn't fair because ROX and Thunar are actually cheating. ;-)

ROX is cheating, because it doesn't determine the type based on the 
contents if compiled w/o gnome-vfs. Instead they use only the file name 
to guess the type, which is of course way faster. I recompiled ROX with 
gnome-vfs now, but didn't check again. It's pretty clear that it'll be 
slower now, tho.

Thunar is cheating, because it doesn't contain any logic for the 
thumbnailing stuff currently, which saves some time per file. Also, 
there is some other stuff, that isn't handled by Thunar yet, but nothing 
that would really add much noticable time to the folder loading stage.

The only "file manager" that was actually faster than Thunar is GNOME 
Commander, but I don't count it as a real file manager, since it doesn't 
determine the MIME type for files and also doesn't load appropriate 
icons for the files (and has some other oddities). No wonder it's 
faster, as it's cheating^2. :-)

So, to continue with the thumbnailing stuff, we have basicly two 
alternatives:

1) Use thumbnails, like other file managers do, in place of mime icons 
in the icon/details view, scaling them to the appropriate size as 
required. The implementation would look similar to the one found in the 
filer snapshot, tho not using D-BUS for the generator this time.

2) Add a separate 'Thumbnail view'. I discovered this in Windows 
Explorer recently.

My two cents: 2) is better from the implementation's POV, while 1) is 
more consistent with what's available currently. That said, if 
thumbnailing will not be taken into account with the usual icon/details 
view, the time spent per file will be reduced (esp. read()'ing stuff in 
~/.thumbnails/ on NFS home dirs), and with a dedicated thumbnail view, 
we could add some nifty stuff like zooming and maybe even previewing 
videos and such w/o blowing (and thereby slowing down) the usual views.

My concern is that this may not be what users expect and may be even 
confusing to not be able to see thumbnails in the usual views.

Maybe Erik or David can enlighten me?

Of course others are also invited to share their opinion, as long as you 
don't come up with "Windows Explorer is evil" or "I don't like that", as 
that won't help. :-)

Benedikt