Resizing and Caching

[dpk3062]

It takes the pi roughly 15 seconds to resize a photo, meaning each image is displayed for at least 15 seconds its first time no matter how fast the slide show is set to run.

Instead of only caching resized images in memory, they should be saved to the disk as well. If a cache hit misses, it should check a directory to see if a resized version of the photo exists.

When an image is resized, it should save a copy of itself.
When an image is to be read in, the disk cache should be checked and the resized version loaded instead. Resized versions should not be re-resized. Only the original image should be adjusted.

The cache folder could contain: imageName-800-by-600.jpg or 800-by-600-imageName.jpg. I'm not sure which is better. One lets you easily order by size while the former lets you order by image duplicates.