Rails4 - 回形针样式中＃和>的含义是什么？

Question

What is the meaning of # and > in the following?

has_attached_file :avatar, 
:styles => {
  :thumb    => ['100x100#',  :jpg, :quality => 70],
  :preview  => ['480x480#',  :jpg, :quality => 70],
  :large    => ['600>',      :jpg, :quality => 70],
  :retina   => ['1200>',     :jpg, :quality => 30]
},

Answer 1

As stays on the official wiki:

• trailing # , thumbnail will be centrally cropped, ensuring the requested dimensions.
• trailing > , thumbnail will only be modified if it is currently larger requested dimensions. (ie the :small thumb for a 120×80 original image will be unchanged)

https://github.com/thoughtbot/paperclip/wiki/Thumbnail-Generation

Answer 2

Paperclip uses ImageMagick to process the images. From their docs :

Use > to shrink an image only if its dimension(s) are larger than the corresponding width and/or height arguments.

As blelump mentioned you should also the the paperclip docs