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

[Robert Krawitz]

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.

(Why 22 GB?  RAW, and especially RAW+JPG, adds up fast with 20MP
cameras.  I shot about 800 frames at a jazz jam this evening and am
killing time while kpa reads them in and builds thumbnails.)

(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.  

-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

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