Example with image magick - load font, background, caption

image_magick_example.rb

  def image_generate
  # composite compartilhar.png ab.png abc.png
  # convert a.png b.png -append ab.png
  # composite -font Raleway-Regular.ttf -size 380x200 -gravity east label:Joaquim abc.png  abcd.png

    file = Tempfile.new(['image1', '.png'])
    file.binmode

    fileAux = Tempfile.new(['image2', '.png'])
    fileAux.binmode

    begin
      refs = []

      image_top = Rails.root + self.clothing_top.image.path
      refs << self.clothing_top.name

      image_bottom = Rails.root + self.clothing_bottom.image.path if self.clothing_bottom.present?
      refs << self.clothing_bottom.name if self.clothing_bottom.present?

      image_extra = Rails.root + self.clothing_extra.image.path if self.clothing_extra.present?
      refs << self.clothing_extra.name if self.clothing_extra.present?

      #top e bottom
      Paperclip.run("convert", " -gravity Center #{image_top} #{image_bottom} -append :dest",
          :dest => File.expand_path(file.path) )

      #floating extra image
      if image_extra.present?
        Paperclip.run("composite", " -gravity North #{image_extra} :dest :dest",
          :dest => File.expand_path(file.path) )
      end

      #background image
      Paperclip.run("composite", " -gravity Center -geometry +115+0 :dest #{Rails.root}/public/bg-img-share.jpg :dest",
          :dest => File.expand_path(file.path) )

      #references
      Paperclip.run("convert", " -background '#e7e7e7' -fill black -border 20x10 -bordercolor '#e7e7e7' -font #{Rails.root}/public/fonts/Raleway-Regular.ttf -size 380x30 -gravity west caption:'ref: #{refs.join(" / ref: ")}' :dest",
        :dest => File.expand_path(fileAux.path) )
        Paperclip.run("composite", " -geometry +50+40   -gravity southwest :dest_aux :dest :dest",
          :dest => File.expand_path(file.path), :dest_aux => File.expand_path(fileAux.path) )


      if self.name.present?
        Paperclip.run("convert", " -font #{Rails.root}/public/fonts/DancingScript-Regular.ttf -size 380x50 -gravity west caption:'por #{self.name}' :dest",
          :dest => File.expand_path(fileAux.path) )

        Paperclip.run("composite", " -geometry +55+55  -gravity West :dest_aux :dest :dest",
          :dest => File.expand_path(file.path), :dest_aux => File.expand_path(fileAux.path) )
      end

      Paperclip.run("composite", " -gravity West #{Rails.root}/public/result.png :dest :dest",
        :dest => File.expand_path(file.path) )

      self.image = file
    ensure
       file.close
       file.unlink   # deletes the temp file
    end
  end