preview in dolphin is slow with many pictures

[Peter Penz]

On Tuesday, 10. June 2008 23:25:30 Mathias Kraus wrote:
[...]
> > I've just submitted a patch which resolves this issue. When the user
> > scrolls down, the generating of previews is paused and resumed again for
> > the new visible area. I've tested it with 1000 items and it seems to work
> > very well.
>
> There is no change for me. I rebuild KDE in release mode, but when preview
> is switched on, I have a delay of several seconds. If I switch preview off,
> the delay is still there until I leave and then enter the folder again,
> then it is really fast. You can try it for example in /usr/bin, there are
> usually also many files.

It works very well here with folders having a lot of images (> 1000 images), 
but I agree that turning on previews in /usr/bin is a huge problem (I was not 
aware about this). I guess this is an issue in kdelibs PreviewJob, where it 
is timeconsuming to retrieve the MIME-type from the files in usr/bin...

In opposite to Gwenview Dolphin tries to create previews for each MIME-type.

> > In opposite to Gwenview Dolphin also created previews for the invisible
> > items in background.
>
> Is it maybe possible to move it into an other thread, or just disable the
> preview creation if number of items is bigger than x?

It is already done this way. The previews are generated by a different thread 
and the user interface is (at least in the case of image previews) not 
blocked. The creating of previews is paused as soon as the user touches the 
scrollbars.

> I also noticed, that 
> the CPU is very high, when dolphin creates the previews.

Sure, creating/loading 1000 previews is resource intensive :-)

>
> Best regards,
> Mathias
>
> > Please note that when testing it in trunk that due to the debug mode the
> > performance of previews in general is quite slow. E. g. when I suspend
> > the previews when touching the scrollbar I've a small delay, which does
> > not occur in the release mode.
> >
> > Best regards,
> > Peter
> >
> > > Is it possible to do it in dolphin the same way and shall a fill a
> > > report on b.k.o?
> > >
> > > Thanks, Mathias