Trouble with Carrierwave :convert

Question

I'd like Carrierwave to produce a few versions of an image, one in png format, and one in jpeg format, but I can't seem to get it to work. I realize several similar questions have been asked both here and elsewhere, but I've failed to find a solution. Roughly, here's what I have:

class MyUploader < CarrierWave::Uploader::Base
  include CarrierWave::RMagick

  version :jpeg do 
    process :convert => 'jpg'
    # more procesors
    process :processed => :jpg
  end

  version :png do
    process :convert => 'png'
    # more processors 
    process :processed => :png
  end

  def store_path(for_file = filename)
    if version_name != :png
      return "#{version_name}.jpg"
    else
      return "#{version_name}.png"
    end
  end

  def filename
    filename = if version_name != :png
      super != nil ? super.split('.').first + '.jpg' : super
    else 
      super != nil ? super.split('.').first + '.png' : super
    end
  end

end

So, regardless of the type of image format I pass in, this produces two files: one named jpg.jpg, and one named png.png. jpg.jpg is indeed always a JPEG file (as verified with Unix's file command), BUT png.png is only a true PNG formated file if and only if I originally pass in a png-formated file (passing in a jpeg results in a jpeg formatted file)!

Ideas?

This might not be useful, but I find the convert method in Carrierwave itself suspicious: convert(some_format) calls manipulate!(:format => some_format), which in turn calls (some_image_object).write("#{some_format}:#{current_path}"). Now if the original image passed in is bla.format (format = jpg, png, etc), current_path with have an extension of .format (tested via a monkey-patch on manipulate!). And the way image format conversion works in RMagick is by calling write with an argument having the desired extension. So why would the jpeg conversion above actually take place? And if so, why would the png conversion fail?

Also, if it's useful, I'm on Rails 3.0.9 and Carrierwave 0.5.6

Thanks!

Answer 1

So I'm not sure why this is the case, but it turns out that the problem is in the # more processors part of the png version which I hid above. Omitting them from the version leads to a genuine PNG file for any input type. These processors call manipulate! and do some stuff. The fix was instead to call manipulate!(:format => 'png') instead. Yay.