This is used to provide higher resolution thumbnails for high pixel
density displays, such as phones or laptops. If your screen has a 2x
pixel density ratio, then 360x360 thumbnails will be rendered at 720x720
resolution.
We use WebP here because it's about 15% smaller than the equivalent
JPEG, and because if a device has a high enough pixel density to use
this, then it probably supports WebP.
720x720 thumbnails average about 36kb in size, compared to 20.35kb for
360x360 thumbnails and 7.55kb for 180x180 thumbnails.
This directory contains library code used through Danbooru. This includes things like defining API clients, dealing with
sources, parsing tag searches, storing and resizing images, and so on.
Many of the files here use the Service Object pattern. Instead of putting complex code in models or controllers, it goes
here, in plain old Ruby objects (POROs). This keeps models and controllers simpler, and keeps domain logic isolated and
independent from the database and the HTTP request cycle.
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