[Thunar-dev] Thumbnails

[Ori Bernstein]

On Tue, 28 Jun 2005 19:52:37 +0200
Benedikt Meurer <benedikt.meurer at unix-ag.uni-siegen.de> said:

> 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.

I'm really not sure either way - I'd probably prefer - as a user - 1 (I don't
want to switch view modes to get a preview of the image I'm looking for, esp.
since Thunar doesn't have a toolbar button to switch views in it's current
iteration), but I can't say it's all that important.

One important thing though, is that the list gets displayed quickly, and
doesn't freeze the filemanager while listing (Nautilus (2.10) *does* freeze when
listing large dirs).

This probably means that one thread lists files and determines mimetype, and
draws it with the generic icon, then dumps it into a queue for the thumbnailer
thread (or even process - more secure, more robust?) to generate and display the
thumbnails.

-- 
The one good thing about repeating your mistakes is that you know when
to cringe.