web_capture.rb

#!/usr/bin/env ruby

require 'capybara-webkit' # '~> 0.14.0'
require 'optparse'
require 'cgi'

options = {}

OptionParser.new do |opt_parser|
  opt_parser.on('-O filename') {|value| options[:filename] = value }
  opt_parser.on('--width size') {|value| options[:width] = value.to_i }
  opt_parser.on('--height size') {|value| options[:height] = value.to_i}
end.parse!


url = ARGV.shift || abort('web_capture.rb [--width n] [--height n] [-O filename] url')

filename = options.delete(:filename) || CGI.escape(url) + '.png'

if File.exist? filename
  abort "#{filename} already exist."
end

puts "capture: #{url}"

driver = Capybara::Webkit::Driver.new(nil)
driver.visit(url)
driver.save_screenshot(filename, options)
puts "saved: #{filename}"