File_column : how can I resize/convert/whatever an image acc

Hi guys,

I want to have a file upload form which would allow the user to ask for
certain transformations of the image before saving it - most
importantly, to
resize it.

Now, how can I make an instance of FileColumn enabled model process
these
imagemagick instructions?

My model looks looks somewhat like :

class Image < ActiveRecord::Base

attr_accessor :resize_dimension, :resize_to

before_save :resize_image

file_column :path,
:versions => { “thumbnail” => “100x100>” }

private
def resize_image

stuff that processes the image with the form-provided values

[:resize_dimension] (can be “w” (width) or “h” (height) ) and
[:resize_to],
so as to obtain the equivalent of “convert -resize ‘250x’ stuff.jpg” or
“convert -resize ‘x100’ stuff.jpg”
end

end

What should I put in that resize_image callback function? Would a
callback be
the DRY way, to begin with?

Any tips, ideas, previous experiences, anyone?

TIA,

Dominique Rose-Rosette