Resize Images Using MiniMagick While Preserving Subdirectory Structure

resizer.rb

require 'fileutils'
require 'mini_magick'

# Get all files of any type within the 4x folder, within any subdirectory
sources = Dir.glob(File.join('**', '4x', '**', '*.png'))

# Create our target directories, and the size factor for that directory
target_directories = [
  { name: '2x', size_factor: 0.5 },
  { name: '1x', size_factor: 0.25 }
]

# Delete old directories and make new ones
target_directories.each do |dir|
  FileUtils.rm_rf(dir[:name])
  Dir.mkdir(dir[:name])
end

sources.each do |item|
  full_path = item.match(%r{4x/(.*/)(.*\.*)})
  subdir_path = full_path.captures[0]
  file_name = full_path.captures[1]

  image = MiniMagick::Image.open(full_path.to_s)

  target_directories.each do |target_dir|
    # Create subdirectories inside target directories with the same exact
    # subdirectory structure as the source
    directory = "#{target_dir[:name]}/#{subdir_path}"
    FileUtils.mkdir_p directory

    # Resize using Image Magick's percentage format, see:
    # http://www.imagemagick.org/script/mogrify.php
    image.resize "#{target_dir[:size_factor] * 100}%"

    # Write resized image into the new directory
    image.write "#{directory}/#{file_name}"
  end
end