paperclip run processors on selected style - ruby-on-rails

Question

I have an :xxx image processor, and I have two styles in the model :big and :thumb.
How I can process with :xxx only the :thumb image leaving the :big image untouched ?

Answer 1

I recently had a similar problem and found this solution on a message board. Hope it helps!
has_attached_file :screenshot,
:default_style => :full,
:styles => {
:full => "280x210",
:cropped => { :processors => [:screenshot_crop] }
}

Answer 2

By default, the Rake task refreshes all thumbnails. Keep in mind that it won't touch / process the original image.
You could have a look at the Rakefile and the Attachment class and modify to allow you to specify a specific thumbnail size, but the current design assumes that you want to take the original and redo all thumbnails from the original.

Answer 3

Add this code to your paperclip.rake file:
desc "Reprocesses your attachments style (set CLASS, ATTACHMENT and STYLE)"
task :style => :environment do
module JustForOneDay
NAME = ENV['STYLE']
end
module ::Paperclip
class Attachment
def post_process_styles #:nodoc:
#styles.each do |name, args|
if JustForOneDay::NAME == name
begin
raise RuntimeError.new("Style #{name} has no processors defined.") if args[:processors].blank?
#queued_for_write[name] = args[:processors].inject(#queued_for_write[:original]) do |file, processor|
Paperclip.processor(processor).make(file, args, self)
end
rescue PaperclipError => e
log("An error was received while processing: #{e.inspect}")
(#errors[:processing] ||= []) << e.message if #whiny
end
end
end
end
end
end
for_all_attachments do |instance, name|
result = instance.send(name).reprocess!
end
end
end
Tested with Paperclip 2.3.1.1
In Paperclip 2.3.3 this should be:
def post_process_styles #:nodoc:
styles.each do |name, style|
if JustForOneDay::NAME == name
begin
raise RuntimeError.new("Style #{name} has no processors defined.") if style.processors.blank?
#queued_for_write[name] = style.processors.inject(#queued_for_write[:original]) do |file, processor|
Paperclip.processor(processor).make(file, style.processor_options, self)
end
rescue PaperclipError => e
log("An error was received while processing: #{e.inspect}")
(#errors[:processing] ||= []) << e.message if #whiny
end
end
end
end
It's easy, just go to attachment.rb file in your paperclip version.

Answer 4

I kludged this--it's not elegant, but it worked for me.
One of your styles should have dimensions different from all the other styles. In this way, in your custom Paperclip Processor, you can see if the contents of the command string contain the given dimensions. If so you would do special processing, if not, you would not.
(I clipped this code -- and modified it -- from Ryan Bate's Railscast Episode 182.)
module Paperclip
class Cropper < Thumbnail
def transformation_command
SPECIAL_PROCESSING_FLAG = "150x150"
if crop_command && super.include?(SPECIAL_PROCESSING_FLAG)
crop_command + super.sub(/ -crop \S+/, '')
else
super 'do nothing fancy
end
end
def crop_command
target = #attachment.instance
if target.cropping?
" -crop '#{target.crop_w.to_i}x#{target.crop_h.to_i}+#{target.crop_x.to_i}+#{target.crop_y.to_i}'"
end
end
end
end
In my situation it didn't matter that we reprocessed in the non-special case too, since the end result changed nothing.