Get image dimensions using Refile

Question

Using the Refile gem to handle file uploading in Rails, what is the best way to determine image height and width during / after it has been uploaded? There is no built in support for this AFAIK, and I can't figure out how to do it using MiniMagick.

Answer 1

@russellb's comment almost got me there, but wasn't quite correct. 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, that's two calls to #to_io >...< The first to_io gives you a Tempfile, which isn't what MiniMagick wants. Hope this helps someone!

-- update --

Additional wrinkle: this will fail if the file is very small (<~20kb, from: ruby-forum.com/topic/106583) because you won't get a tempfile from to_io, but a StringIO. You need to fork your code if you get a StringIO and do:

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

So my full code is now:

# 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