Gif image resizing does not work as expected

[xdays]

The original gif is:

But what I get is:

Are you using the latest version? Is the version currently in use as reported by npm ls sharp the same as the latest version as reported by npm view sharp dist-tags.latest?

root@24d4f802e1f7:/tmp# vips -v
vips-8.10.0-Sat Jul 18 13:45:47 UTC 2020
root@24d4f802e1f7:/tmp# npm ls sharp
demo@1.0.0 /tmp
`-- sharp@0.26.0

What are the steps to reproduce?

const sharp = require('sharp');

sharp('t.gif', {
  animated: true
}).resize(160).toFile('o.gif', (err, info) => {
  console.log(err, info)
});

and I can resize with pyvips, so I'm sure libvips works:

import pyvips
thumb = pyvips.Image.thumbnail("t.gif[n=-1]", 160)
thumb.write_to_file("x.gif")

What is the output of running npx envinfo --binaries --system?

npx: installed 1 in 3.094s

  System:
    OS: Linux 4.19 Debian GNU/Linux 9 (stretch) 9 (stretch)
    CPU: (4) x64 Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
    Memory: 6.01 GB / 7.78 GB
    Container: Yes
    Shell: 4.4.12 - /bin/bash
  Binaries:
    Node: 12.18.3 - /usr/local/bin/node
    Yarn: 1.22.4 - /usr/local/bin/yarn
    npm: 6.14.6 - /usr/local/bin/npm

[lovell]

Hi, you'll need to manually set pageHeight - see https://sharp.pixelplumbing.com/api-output#gif

There's a future possible enhancement at #2275 to make this easier.

[xdays]

Thanks @lovell , it works now.