How to resize an image but keep it's orientation and aspect ratio ? (gm)

Question

I would like to resize an image to a maximum height of 400px, while keeping its orientation and aspect ratio.

This resizes the image, but changes its orientation (if it is portrait it changes it to landscape).

 gm(file.stream)
    .resize('400')

Answer 1

Ah, found it.

 gm(file.stream)
    .resize('400','400')
    .autoOrient()