Ruby script that resizes the height of a chrome window by a fixed amount of pixels. Useful for debugging CSS/JS animation issues.

resizer.rb

require 'shellwords'

def tell_chrome_to(*commands)
  tell(%Q(application "System Events" to tell application process "Google Chrome"), *commands)
end

def tell(target, *commands)
  ["tell #{target}", *commands.flatten, 'end tell']
end

def osascript(*commands)
  commands = commands.flatten.map(&Shellwords.method(:escape))
  arguments = (["-e"] * commands.length).zip(commands).flatten.join(' ')
  `osascript #{arguments}`.chomp
end

def desired_pixels
  input = gets.strip

  if input.match?(/q/)
    exit 0
  elsif input == ""
    input = 1
  else
    input = input.to_i
  end
end

begin
  dimensions = osascript tell_chrome_to("get size of window 1")
  width, height = dimensions.split(",").map(&:to_i)

  while true do
    print "Reduce window height by how many pixels? (1): "

    height -= desired_pixels

    puts "Resizing to height: #{height}"

    osascript tell_chrome_to(tell("window 1", "set {size} to {{#{width}, #{height}}}"))
  end
rescue SystemExit, Interrupt
  exit
end