Auto-detect animated sources

Currently, if you want animated output you need to specifically choose it. It would be good if animated webp input images could automatically generate animated output. I’m not sure what the overhead would be of just passing animated to the sharp constructor every time.

[lovell]

If you hadn’t already seen, support for resizing and cropping animated GIF and WebP images was added in sharp v0.30.0.

https://sharp.pixelplumbing.com/changelog

const data = await sharp('in.gif', { animated: true })
  .resize({ width: 128, height: 128 })
  .toBuffer()

[lovell]

Is there any reason to not always pass animated: true when optimizing images?

@pi0 Always passing animated: true looks like the right approach for the scenarios ipx supports.

Is there any way to get the number of pages in a gif, or the individual page height, after it is converted to a Buffer from within the callback?

@tgcallaway Not directly at the moment. Adding pageHeight to the info object in the response would make a good improvement - please feel free to open an enhancement issue for this.