Compress PNGs using the TinyPNG service.

tiny_png.rb

require "net/https"
require "uri"

# Ensure we have two parameters.
if ARGV.length != 2
    puts "Usage: #{$0} input_directory output_directory"
    exit 1
end

key = "PLACE_TINY_PNG_KEY_HERE"
input_dir  = ARGV[0]
output_dir = ARGV[1]

# Get an array of PNG files within the input directory.
png_files = Dir["#{input_dir}/*.png"]

# Exit if there are no PNG files.
if png_files.length == 0
    puts "No PNG files in #{input_dir}."
    exit 1
end

# Create output directory if it doesn't exsit.
Dir.mkdir(output_dir) unless Dir.exists?(output_dir)

# We're good to start using tinypng to compress.
uri = URI.parse("https://api.tinypng.com/shrink")

http = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true

png_files.each do |input_file|
    output_file = "#{output_dir}/#{File.basename(input_file)}"

    puts "Processing #{input_file} => #{output_file}"

    request = Net::HTTP::Post.new(uri.request_uri)
    request.basic_auth("api", key)

    response = http.request(request, File.binread(input_file))
    if response.code == "201"
      # Compression was successful, retrieve output from Location header.
      File.binwrite(output_file, http.get(response["location"]).body)
      puts " -> OK"
    else
      # Something went wrong! You can parse the JSON body for details.
      puts " -> FAILED Compression failed. Exiting."
      exit 1
    end
end