[KPhotoAlbum] Perf suggestion: build thumbnails as images are being read

Robert Krawitz rlk at alum.mit.edu
Mon Dec 7 23:26:02 GMT 2015

On Mon, 07 Dec 2015 22:07:28 +0100, Johannes Zarl-Zierl wrote:
> Hello Robert,
> On Sunday 06 December 2015 19:50:58 Robert Krawitz wrote:
>> At present, kpa scans all of the images, and then builds thumbnails in
>> a separate pass.  When reading a very large number of photos (such
>> they don't stay in RAM), this results in each image file having to be
>> read twice.  That's somewhat time consuming for e. g. 22 GB of photos.
> I think this will be tricky to pull off without major changes to KPA.
> OTOH you are absolutely correct that this will probably be a relevant speedup, both for users with RAW workflows and for users with NFS shares.
> For optimal performance, though, all file access should be bundled to a single pass: reading EXIF info and other metadata, recomputing checksums - this can also be done more intelligently, AFAIK.

It's something that would be worth thinking about.

>> (It would be even faster if kpa could read photos directly from a
>> source and place them in the image tree according to appropriate rules
>> as it's reading them in.
> This part should be far easier to implement: KPA just needs to look up the thumbnail from the freedesktop.org thumbnail store first. Writing a shell script that creates those thumbnails is straightforward. Bonus: dolphin and gwenview get the same thumbnails without further processing.

I'm not sure what you're referring to (in particular, the
freedesktop.org thumbnail store).  In this case, I have a card reader
with my CF card.  I use a shell script to copy the new images into my
kpa directory, and then run kpa.  What I'm proposing is for kpa to be
able to do that image copy (perhaps by means of a plugin, if that's
possible in this case) and do the checksum, EXIF, and thumbnail
generation in the process of doing that copy.
Robert Krawitz                                     <rlk at alum.mit.edu>

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