Converts images in a directory to pdf

images_to_pdf.rb

#!/usr/bin/env ruby

###############################################################################
# Pre-requirements
#
# - sudo apt update & sudo apt install imagemagick libmagick++-dev
# or
# - brew install imagemagick
#
# - gem install mini_magick prawn
###############################################################################

require 'prawn'
require 'mini_magick'

SIZES = {
  "4A0" => [4767.87, 6740.79],
  "2A0" => [3370.39, 4767.87],
  "A0" => [2383.94, 3370.39],
  "A1" => [1683.78, 2383.94],
  "A2" => [1190.55, 1683.78],
  "A3" => [841.89, 1190.55],
  "A4" => [595.28, 841.89],
  "A5" => [419.53, 595.28],
  "A6" => [297.64, 419.53],
  "A7" => [209.76, 297.64],
  "A8" => [147.40, 209.76],
  "A9" => [104.88, 147.40],
  "A10" => [73.70, 104.88],
  "B0" => [2834.65, 4008.19],
  "B1" => [2004.09, 2834.65],
  "B2" => [1417.32, 2004.09],
  "B3" => [1000.63, 1417.32],
  "B4" => [708.66, 1000.63],
  "B5" => [498.90, 708.66],
  "B6" => [354.33, 498.90],
  "B7" => [249.45, 354.33],
  "B8" => [175.75, 249.45],
  "B9" => [124.72, 175.75],
  "B10" => [87.87, 124.72],
  "C0" => [2599.37, 3676.54],
  "C1" => [1836.85, 2599.37],
  "C2" => [1298.27, 1836.85],
  "C3" => [918.43, 1298.27],
  "C4" => [649.13, 918.43],
  "C5" => [459.21, 649.13],
  "C6" => [323.15, 459.21],
  "C7" => [229.61, 323.15],
  "C8" => [161.57, 229.61],
  "C9" => [113.39, 161.57],
  "C10" => [79.37, 113.39],
  "RA0" => [2437.80, 3458.27],
  "RA1" => [1729.13, 2437.80],
  "RA2" => [1218.90, 1729.13],
  "RA3" => [864.57, 1218.90],
  "RA4" => [609.45, 864.57],
  "SRA0" => [2551.18, 3628.35],
  "SRA1" => [1814.17, 2551.18],
  "SRA2" => [1275.59, 1814.17],
  "SRA3" => [907.09, 1275.59],
  "SRA4" => [637.80, 907.09],
  "EXECUTIVE" => [521.86, 756.00],
  "FOLIO" => [612.00, 936.00],
  "LEGAL" => [612.00, 1008.00],
  "LETTER" => [612.00, 792.00],
  "TABLOID" => [792.00, 1224.00],
}

def get_page_size(img, paper)
  paper = "A4" if paper.nil?
  size = SIZES[paper.upcase]
  ratio = img.width.to_f / img.height.to_f
  [size[0], size[0] / ratio]
end

def get_images(image_folder, output_file)
  unless Dir.exist?(image_folder)
    puts "The image folder '#{image_folder}' does not exist."
    exit
  end

  output_dir = File.dirname(output_file)
  unless Dir.exist?(output_dir)
    puts "The output directory '#{output_dir}' does not exist."
    exit
  end

  images = Dir.glob(File.join(image_folder, '*.{png,jpg,jpeg}'))
  if images.empty?
    puts "No images found in the folder '#{image_folder}'."
    exit
  end

  images
end

def images_to_pdf(image_folder, output_file, paper)
  imgs = get_images(image_folder, output_file)
  img = MiniMagick::Image.open(imgs.first)
  pdf = Prawn::Document.new(margin: 0, page_size: get_page_size(img, paper))

  imgs.sort!
  imgs.each do |image_path|
    puts "Processing '#{File.basename(image_path)}'..."

    img = MiniMagick::Image.open(image_path)
    unless ['jpg', 'jpeg', 'png'].include?(img[:format].downcase)
      img.format 'png'
      img.write(image_path)
    end

    pdf.start_new_page if pdf.page_count > 1
    pdf.image img.path, fit: [pdf.bounds.width, pdf.bounds.height]
  end

  pdf.render_file output_file
end

if ARGV.length < 2 || ARGV.length > 3
  puts "Usage: ruby script.rb <image_folder> <output_file.pdf> [A4|LETTER]"
  exit
end

images_to_pdf(ARGV[0], ARGV[1], ARGV[2])