Support pixiv ugoira

[contextnerror]

Example post https://www.pixiv.net/en/artworks/44298467

Currently if the popup is opened while the image is in zoomed out mode, a sample is fetched (https://i.pximg.net/c/540x540_70/img-master/img/2014/06/25/14/30/22/44298467_master1200.jpg)

When zoomed in the correct size image is fetched, but only the first frame (https://i.pximg.net/img-original/img/2014/06/25/14/30/22/44298467_ugoira0.jpg)

Not sure whether the best approach here would be to make all frames available individually or to stitch them together into a different format.

It also seems like sometimes some work needs to be done to ensure that the frames downloaded are the original? See https://github.com/danbooru/danbooru/issues/2572 for more details (some examples in that issue are NSFW)

Unfortunately I don't understand the technical aspects of this at all, so I can't provide much help.

[qsniyg]

Thanks for the information! Here's a SFW link: https://www.pixiv.net/en/artworks/52592934

Currently, frame-based animations aren't supported in the popup, so I'd have to add support for that before supporting this.