No `pages` metadata for animated gif

Maybe I’m doing something wrong but whenever I load an animated gif and do operations on it, I always end up with the first frame transformed and that’s it.

In order to determine if this was due to something deep into our code, I looked more closely into the metadata reported by sharp for animated gifs.

From what I understand from the docs, an animated image is supposed to give a pages value that is a number.

If I input an animated monkey found online, I end up with a metadata.pages that’s undefined and sharp only acts on the first frame.

Is this by design? Am I missing something?

Also, I saw outputting animated webp was supported but is outputting apng supported too? Could be nice to have a clear support grid somewhere in the docs where this kind of things would be listed. But I know how difficult and time-consuming writing docs can be 😉

[lovell]

It looks like libvips 8.8.0 is required for the pages property - see https://github.com/libvips/libvips/commit/2968bee3fa933f08a0f0bd4686eff43ee9176c55

[tomgallagher]

@lovell If the Sharp API need to change to accommodate libvips v8.8.0, I can help with the documentation if that’s plausible and time-saving.