Image Loading Library

Design an image-loading library for mobile apps. It should load images into views, share compatible work, cache results, and stop unnecessary work when a caller no longer needs it.

The host owns the view lifecycle and overall memory budget. The library must work within both.

1. Define the request and handle

An illustrative API is:

load(request, target) -> subscription handle
prefetch(request, policy) -> subscription handle
cancel(handle)
invalidate(resourceIdentity)
trimMemory(level)