[KimDaBa] performance improvements - patch

Jesper K. Pedersen blackie at blackie.dk
Sun Jun 13 18:45:29 CEST 2004

Thanks for a very welldone patch. It has been applied.

If you'd like to work a bit more on KimDaBa, I'd happy to get a patch from 
you, which adds the same kind of caching in the Viewer class.


On Saturday 12 June 2004 21:24, Marcel Wiesweg wrote:
| when I started to work with KimDaBa, I noticed first that it is an
| excellent piece of work, and second a few major performance hits:
| 1. Thumbnail creation. A 64x64 thumbnail from a 3.2 Megapixel image took
| ~1.2 seconds on my machine. Imagine me sitting in front of 1000+ images to
| classify...
| 2. The "one-at-a-time" ImageConfig dialog took veeery long to appear (3 s)
| 3. Switching to the next image in the same dialogue also took a good time.
| I traced all the problems in last consequence down to the thumbnail
| creation. The patch attached does the following:
| - make use of libjpeg and its scale-while-decoding capability wherever
| possible (now thumbnail takes ~0.2s => factor 6)
| - use the excellent ImageManager/ImageLoader infrastructure in the
| ImageConfig dialogue - if necessary, the preview appears after a short
| delay
| - use a preloading mechanism in this dialogue: The next image is preloaded,
| the last is kept in cache. This has the effect that in 'normal' operation
| the preview always appears instantly.
| You will see that I added the libjpeg decoding and a central function
| getThumnailName(QString filename) to util.cpp

Having trouble finding a given image in your collection containing
thousands of images?

http://ktown.kde.org/kimdaba might be the answer.

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