Get image sizes with Refile

Question

Using the Refile gem to handle file uploads in Rails, what is the best way to determine the height and width of the image during / after it was uploaded? There is no built-in support in this AFAIK, and I cannot figure out how to do this using MiniMagick.

Answer 1

Comment

@russellb almost got me, but not quite right. If you have a Refile :: File called @file, you need to:

fileIO = @file.to_io.to_io
mm = MiniMagick::Image.open(fileIO)
mm.width # image width
mm.height # image height

Yes, two calls to #to_io> ... <The first to_io gives you a Tempfile, which MiniMagick does not want. Hope this helps someone!

- update -

: , (< ~ 20kb, from: ruby-forum.com/topic/106583), to_io, StringIO. , StringIO :

mm = MiniMagick::Image.read(fileio.read)

, :

# usually this is a Tempfile; but if the image is small, it will be 
# a StringIO instead >:[
fileio = file.to_io

if fileio.is_a?(StringIO)
  mm = MiniMagick::Image.read(fileio.read)
else
  file = fileio.to_io
  mm = MiniMagick::Image.open(file)
end

Answer 2

reffile to_io (. Refile:: File docs), -, MiniMagick.

, file (, file_id) width height, :

class Image < ActiveRecord::Base

  attachment :file

  before_save :set_dimensions, if: :file_id_changed?

  def set_dimensions
    image = MiniMagick::Image.open(file.to_io)
    self.width = image.width
    self.height = image.height
  end

end

, .

Answer 3

MiniMagick ( ).

image = MiniMagick::Image.open('my_image.jpg')
image.height #=> 300
image.width  #=> 1300

This is all well documented in README.md for the gem: https://github.com/minimagick/minimagick