Bug 314278

Summary:	kio_thumbnail recompute unnecessary thumbnails for .kra and .ora
Product:	[Unmaintained] kio	Reporter:	David REVOY <info>
Component:	thumbnail	Assignee:	Unassigned bugs <unassigned-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	minor	CC:	kossebau
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Ubuntu
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description David REVOY 2013-02-01 23:34:08 UTC

Hi, I have the filter 'open raster' and 'calligra files' added for seing thumbnails in my Dolphin . I'm having slow down navigating on big folders of heavy *.ora ( open raster ) and *.kra files ( Krita native files). I'm a digital painter. So , most of my files are of this type. 

I saw after spying system monitor activities that kio_thumbnail was having hard time computing the thumbnails. And they appear one by one slowly. 

I was wondering ; does Kio really re-render the thumbnail one by one ? or does it just take this time to read the embed thumbnail into the file ? ( both *.ora and *.kra are archive , with already a thumbnails inside them rendered by the software at saving ). I saw it way faster in Thunar or Nautilus ( with plugin for *.ora ) , so I find it suspicious...
 
other infos :
for *.kra : 'preview.png' is at the root inside the archive
for *.ora : 'thumbnail.png' is inside a 'Thumbnails' folder inside the archive

Comment 1 Friedrich W. H. Kossebau 2013-08-15 21:09:03 UTC

The calligra thumbnailing plugin should actually take the embedded thumbnails out of the files, see CalligraCreator::create() in https://projects.kde.org/projects/calligra/repository/revisions/master/entry/extras/thumbnail/calligracreator.cpp#L55

Just tested it with ora and kra files, and that also happens for me. The only issue is that those thumbnails are then copied to the system thumbnail cache, because there is no support for noting that thumbnails are already stored embedded.

But there is a case even with embedded previews existing:
if the requested size is larger than the existing thumbnails,
!(thumbnail.width() >= width && thumbnail.height() >= height)
then a new preview is rendered.

You could test things like that: copy a few ora files to a new directory, then start dolphin from the commandline, so you see also the output of kio_thumbnail. Go to the directory with Dolphin, enable preview and check the log: if you see just a few lines with
kio_thumbnail [...] KoStore::open: Opening for reading "Thumbnails/thumbnail.png"
then the embedded preview is taken. Does that happen for you?

Comment 2 David REVOY 2013-08-16 07:40:18 UTC

I confirm ; now I understand better the behavior. The max size for no recompute is to set the zoom slider to '80px' , above this a new larger thumbnail is requested. 

The bigger thumbnail is also automatically requested if :
* User got a side pan preview in Dolphin
* User got in Preference > General > Show tooltips activated ( a preview of the file on mouse:hover )

So, Dolphin/thumbnailer will not recompute if :
* I remove the side docker preview 
* turn off the option 'show tooltips' 
* set zoom to 80px max 

Now, I can browse very fast large collections of *.ora and *.kra. 
This report can be turn to 'resolved' .