CSS Sprite Generator

csssprite.rb

#!/usr/bin/env ruby 
# -*- coding: utf-8 -*-

# 
# CSS Sprite Generator
# require imagemagick
# require Ruby >= 1.9
# Usage:
#   ruby csssprite.rb file1 file2 file3 [options]
# Options:
#   --offset        put each image at every <offset> pixel
#   --horizontal    put images horizontally
#

require 'optparse'

def create_sprite(images, offset = nil, is_horizontal = false)
  raise 'This script needs imagemagick' if !imagemagick_exists?
  sizes = `identify -format "%w %h\t" #{images.join(" ")}`.chomp.split("\t").map {|item| item.split(' ').map(&:to_i)}
  positions = calc_positions(sizes, offset, is_horizontal)
  base = base_size(sizes, offset, is_horizontal)
  cmds = []
  cmds << "convert -size #{base[0]}x#{base[1]} xc:transparent png:-"
  positions.each_with_index do |position, i| 
    cmds << "composite -geometry +#{position[0]}+#{position[1]} #{images[i]} - png:-"
  end
  puts `#{cmds.join(' | ')}`
end

def calc_positions(sizes, offset, is_horizontal)
  tmp = []
  if offset
    sizes.each_with_index do |item, i|
      tmp << (is_horizontal ? [offset * i, 0] : [0, offset * i])
    end
  else
    sizes.inject(0) do |res, item|
      if is_horizontal
        tmp << [res, 0]
        res + item[0]
      else
        tmp << [0, res]
        res + item[1]
      end
    end
  end
  tmp
end

def base_size(sizes, offset, is_horizontal)
  if offset
    if is_horizontal
      [(sizes.length - 1) * offset + sizes.last[0], sizes.transpose[1].max]
    else
      [sizes.transpose[0].max, (sizes.length - 1) * offset + sizes.last[1]]
    end
  else
    if is_horizontal
      [sizes.transpose[0].inject(:+), sizes.transpose[1].max]
    else
      [sizes.transpose[0].max, sizes.transpose[1].inject(:+)]
    end
  end
end

def imagemagick_exists?
  !(`which convert`.empty? || `which composite`.empty? || `which identify`.empty?)
end

OptionParser.new do |opt|
  offset = nil
  is_horizontal = false
  opt.on('--horizontal [HORIZONTIAL]') do |i|
    ARGV.unshift(i)
    is_horizontal = true
  end
  opt.on('--offset OFFSET', Integer) do |i|
    offset = i
  end
  opt.permute!(ARGV)
  create_sprite(ARGV, offset, is_horizontal)
end