[KPhotoAlbum] RFC: remove interactive thumbnail resizing

Risto H. Kurppa risto at kurppa.fi
Tue Mar 8 08:38:38 GMT 2011

Hi there and thanks for taking this to the list!

The reason why I started to talk about this was that having a huge
database of photos and yes, changing the thumb size every now and then
(not often - but not so often is often enough as generating the thumbs
takes a long time and makes a core2duo system very sluggish) results
in that I every now and then end up scrolling through photos and the
thumbs are generated dynamically.

As now they're generated in 'progressive' mode, it's slow to scroll
and try to find a set of photos you're looking for.
The 'interlaced' approach (load every second thumb) would make it a
bit faster to scroll.
see http://www.codinghorror.com/blog/2005/12/progressive-image-rendering.html
for differences of interlaced and progressive when loading a single

On Tue, Mar 8, 2011 at 10:11 AM, Jan Kundrát <jkt at gentoo.org> wrote:
> Risto has proposed an interesting idea on IRC, that it could make sense
> to load only every second image in the thumbnail view before the rest of
> them. I don't like this approach, because:
> a) "Every second" feels like an arbitrary heuristic to me,

Sounds like interlaced to me :)

> b) It's a *lot* of work,

I know nothing about this..

> c) It tries to fix a symptom rather than the problem,

The problem is slow thumbnail generation

> d) Who keeps resizing the thumbnail widget all the time?

I do, every now and then.
Also people, who start to use KPA, don't have existing thumbs that
could be loaded but they end up in the same situation: the computer
(possibly) feels sluggish pregenerating thumbs - and they try to
scroll through their photos at the same time.. Not very impressive
user experience, I'd guess.

> So, it occured to me that it might make sense to disable the interactive
> resizing of the cell size in thumbnail widget. Maybe it's too Gnome-ish
> :), but at least it would make it obvious that when one resizes the
> grid, it will take time to load the images again.

I agree, this is very Gnome-ish and would like to avoid that ;)
Jesper suggested adding a warning about flushing the cache.
I think that's a easy(?) solution that'd help a bit, but doesn't solve
the actual problem, that when you resize (yes, sorry, at least I use
it :) the thumbs, things get very slow.

> Another way would be not to flush the thumbnail cache at that point, but
> queue a regeneration of images. I'm not sure if that's a great idea, and
> I suspect it's not even possible with our current code to return a
> "rough" pixmap followed by a "fine" version later on...

In theory sounds ok but codewise no idea if it'd work.

Jesper told that implementing the interlaced thumb loading would be a
lot of coding so I'm not trying to say that now, immediately, someone
has do it. Of course in the FLOSS world there are huge rewrites done
here and there but I'm sure this is not a reason good enough to do the
work - unless someone able to code feels a need for this and has the
time to implement it. But I don't expect that to happen.

I feel respected that my idea was received and understood. Also other
solutions to the problem were thought.
I think this is the correct way the developers should communicate with
the community.
Managing community well doesn't mean that every new idea is
implemented, but giving a thought is a decent reception that
encourages people to continue participating.

So well done & thanks Jan & Jesper & other devels!

Even though I'm satisfied here, I'm interested to hear what others
think. How often do you resize your thumbs, how well do you think the
thumbnail generation (both pregeneration and dynamical) work. How
about new user experience? (Do we have any new users around..?)

Enjoy your freedom!


| risto h. kurppa
| risto at kurppa dot fi
| http://risto.kurppa.fi

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