Comment 3 for bug 1467740

Well, consider the cost of scaling down from a full-size photo to a thumbnail. It takes a quarter of a second on a Nexus 4.

Surely, it's not too much to ask the caller what size thumbnail it wants? If we are not told what size the caller needs, we can either deliver the full-size image, which is really expensive and eats a lot of disk space, or we can deliver some thumbnail that is arbitrarily smaller and ends up getting scaled up and looking bad. Either the battery loses or the user experience loses.

The meaning of (0, 0) is "give me the best thumbnail available". We'll faithfully do that. We ask that callers use this feature judiciously because it is expensive. The meaning of (-1, -1) is "I don't know what I need, just give me something." I don't think that's a good idea, and we should never have supported that feature in the first place. If the caller doesn't know what size image it needs, there is a problem with the caller, I think.

If the caller doesn't mind scaling up and the loss of image quality, it is free to ask for (256, 256) or whatever, and we'll provide that. The point here is that the thumbnailer has no business setting policy. The policy is up to the caller.