windowsでアクティブなウィンドウのタイトルを取得する

getActiveWindowTitle.rb

$ gem install win32-api
※参考 http://stackoverflow.com/questions/14220386/ruby-win32-api-getfocus-and-getwindowtext

require 'win32/api'
include Win32
while true do
  hwnd = GetActiveWindow = API.new('GetForegroundWindow', 'V', 'L', 'user32').call
  GetWindowText       = API.new('GetWindowText', 'LPI', 'I', 'user32')
  GetWindowTextLength = API.new('GetWindowTextLength', 'L', 'I', 'user32')
  buf_len = GetWindowTextLength.call(hwnd)
  str = ' ' * (buf_len + 1)
  # Retreive the text.
  result = GetWindowText.call(hwnd, str, str.length)
  puts str.strip
  sleep 1
end