pdfcompress.rb

#!/usr/bin/env ruby
require 'colorize'

HEADER = %Q{
  pdfcompress: compresses a pdf using graphicsmagick.
  Author: Johannes Hertenstein

  Usage:
    $pdfcompress.rb $input $output [$quality]

    - $input: path of the original file. Can be absolute or relative.
    - $output: path of the new file that will be created. Can be absolute or relative
    - $quality: (optional) The quality level that should be used to compress. will default to "ebook"
                Available levels (from lowest to highest):
      - screen
      - ebook
      - printer
      - prepress

}

validQualities = ["screen", "ebook", "printer", "prepress"];

# executes a command, prints stdout to commandline and returns it to the caller
def execute(cmd, out  = true)
	puts "$ #{cmd}".blue;
	lines = [];
	IO.popen(cmd) {|io|
		io.each { |line|
			print line.light_black if out;
			lines.push(line);
		}
	}

	Process.waitall();
	return lines.join("\n");
end

#
# If there are not enough parameters, we show the header
#
if ARGV.length < 2
  puts HEADER;
  exit(1);
end

#
# getting the arguments
#
infile = ARGV[0];
outfile = ARGV[1];
quality = validQualities[1];

if ARGV.length > 2
  quality = ARGV[2];
end

#
# checking the arguments
#
if !File.exists?(infile)
  puts HEADER.light_black;
  puts "Error: input file #{infile} does not exist".red;
  exit(2);
end
if File.exists?(outfile)
  puts HEADER.light_black;
  puts "Error: output file #{outfile} already exists".red;
  exit(3);
end
if !validQualities.include?(quality)
  puts HEADER.light_black;
  puts "Error: quality #{quality} is not valid. Must be one of #{validQualities}".red;
  exit(4);
end
puts "Using quality level #{quality}";

#
# Do the magick
#
execute("gs -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dPDFSETTINGS=\"/#{quality}\" -sOutputFile=\"#{outfile}\" \"#{infile}\"");

#
# outputs the size of the input and output files in MB
# TODO: dynamically choose other units
#
sizeIn =  (File.size(infile)  / 1024 / 1024).round(2);
sizeOut = (File.size(outfile) / 1024 / 1024).round(2);

puts "\n";
puts "Input file:   #{sizeIn} MB".green;
puts "Output file:  #{sizeOut} MB".green;