Attachment_fu: save to a default format

comopasta · January 19, 2009, 8:51am

Hi, would anyone have any advices on the next?

I allow users to upload images to my app. I’m using attachment_fu and
MiniMagick.
There’s two things that I’d like to do:

1- No matter what format the original file is I’d like to save it in jgp
format.
2- I want to keep all images limited to say 1000px width, so resize if
they are bigger.

Is there a way to do that without much hassle?

Thanks.

comopasta · January 19, 2009, 2:46pm

Resizing is a basic feature, take a look at the README. Format
transformation, on the other hand, is more difficult and is not a
known feature of attachemnt_fu…

Cheers, Sazima

On Jan 19, 5:51 am, comopasta Gr [email protected]

comopasta · January 20, 2009, 1:18am

Here’s an example of how to do what you want with Rmagick (probably
works in
principle with mini magick, but not sure):

github.com

kete/kete/blob/3ae3c179f86943ccccaf5a15d8b5590a28c0ae6e/lib/resize_as_jpeg_when_necessary.rb

# from http://blog.airbladesoftware.com/2008/1/15/converting-image-format-when-thumbnailing
# modified to use more standard tools, i believe there was some unnecessary code in here
# basically, i'm running on the assumption that if the original is not jpeg, gif, or png
# we should convert it to jpeg
# this obviously is deeply dependent on use of AttachmentFu plugin with Rmagick
module ResizeAsJpegWhenNecessary
  unless included_modules.include? ResizeAsJpegWhenNecessary
    # declarations
    def self.included(klass)
      klass.send :before_thumbnail_saved do |record|
        record.content_type = 'image/jpeg' if record.class.should_be_converted?(record.parent.filename)
      end

      klass.extend(ClassMethods)
    end

    module ClassMethods
      def should_be_converted?(name)
        ext = File.extname(name).gsub(".", "")
        # we leave along formats that make thumbnails fine themselves

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It’s a module we mix in to monkey patch (i.e. redefine methods locally)
attachment_fu’s built in processor code for Rmagick in the Kete app (
http://kete.net.nz).

Cheers,
Walter

comopasta · January 20, 2009, 6:51am

Hi, thanks for the comments!

This is a great piece of information.

Regards.