gistfile1.rb

  def upload_sizing
    result = {:export => {use: []}}
    
    return result unless self.uploads_enabled?
    
    
    if self.upload_width? && self.upload_height?
      if self.enable_images?
        result[:resize] = {
          width: self.upload_width,
          height: self.upload_height
        }
      end
      
      if self.enable_videos?
        result[:encode] = {
          width: self.upload_width,
          height: self.upload_height
        }
      end
    end
    
    
    if self.upload_thumb_width? && self.upload_thumb_height?
      if self.enable_images?
        result[:resize_thumb] = {
          width: self.upload_thumb_width,
          height: self.upload_thumb_height
        }
      end
      
      if self.enable_videos?
        result[:encode_thumb] = {
          width: self.upload_thumb_width,
          height: self.upload_thumb_height
        }
      end
    end
    
    result[:export][:use].push("resize").push("resize_thumb") if self.enable_images?
    result[:export][:use].push("encode").push("encode_thumb") if self.enable_videos?
    
    result
  end

https://gist.github.com/959622

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Elliot's: https://gist.github.com/959710