Rake task to generate font icons from a folder full of SVGs

icons.rake

require 'fileutils'

RANGE = (0xe000...0xf8ff);

def map_fonts(src, map_file)
  map = {
    'meta' => {
      'author' => "Redbubble"
    },
    'font' => {
      'version' => "1.0",
      'fontname' => "rb-icons",
      'fullname' => "rc-icons",
      'familyname' => "rb-icons",
      'weight' => 400,
      'units-per-em' => 500,
      'ascent' => 500,
      'descent' => 0
    },
    'glyphs' => []
  }

  map = YAML.load_file(map_file) if File.exist?(map_file)
  used = map['glyphs'].map{ |g| g['code'] }

  Dir.glob("#{src}/*.svg").each do |path|
    filename = path.split(File::SEPARATOR).last
    name = filename.gsub(/\.svg$/, "")

    unless map['glyphs'].map{ |g| g['css'] }.include?(name)
      next_hex = (RANGE.to_a - used).first

      puts "We've run out of private font addresses!" && exit unless next_hex
      map['glyphs'].push({
        'css' => name,
        'file' => filename,
        'code' => next_hex
      })
      used << next_hex
    end
  end

  File.write map_file, map.to_yaml
end

def convert_fonts(src, dest, map_file)
  map_fonts(src, map_file) unless File.exist?(map_file)
  pwd = Rails.root.join('script', 'svg2font', 'node_modules', '.bin').to_s
  puts("Please 'run npm install' from #{pwd}") and exit unless Dir.exist?(pwd)

  puts `cd #{pwd}/../../ && #{pwd}/svg-font-create --config="#{map_file}" --input_dir="#{src}" --output="#{dest}.svg"`
  puts `#{pwd}/svg2ttf #{dest}.svg #{dest}.ttf`
  puts `#{pwd}/ttf2woff #{dest}.ttf #{dest}.woff`
  puts `#{pwd}/ttf2eot #{dest}.ttf #{dest}.eot`
end

def generate_scss(scss, map_file)
  puts('Please generate a map file') and exit unless File.exist?(map_file)
  map = YAML.load_file(map_file)

  name = map['font']['fontname']
  icons = map['glyphs'].map { |g| "#{g['css']}: '\\#{g['code'].to_s(16)}'" }

output = <<-EOF
// This file is automatically generated. Any changes will be overwritten
$icon-font-family: '#{name}';

@font-face {
  font-family: '#{name}';
  src: font-url('#{name}.eot');
  src: font-url('#{name}.eot#iefix') format('embedded-opentype'),
       font-url('#{name}.woff') format('woff'),
       font-url('#{name}.ttf') format('truetype'),
       font-url('#{name}.svg##{name}') format('svg');
  font-weight: normal;
  font-style: normal;
}

$icon-map: (
#{icons.map{ |g| "  #{g}" }.join(",\n")}
);
EOF

  File.write(scss, output)
end

namespace :icons do
  desc "Convert a folder of SVGs into a set of icon font files. Also generates a .scss file with the correct mappings"
  task :generate => :environment do
    src = Rails.root.join('app', 'assets', 'svgs')
    dest = Rails.root.join('app', 'assets', 'fonts', 'rb-icons')
    scss = Rails.root.join('app', 'assets', 'stylesheets', 'new_layout', '_icon_map.scss')
    map = Rails.root.join('config', 'icon_map.yml')

    map_fonts(src, map)
    convert_fonts(src, dest, map)
    generate_scss(scss, map)
 end
end