## 指定したウインドウクラスから最後にアクティブだったウインドウのタイトルを取得する
##
## active_title = get_activewin_title( "OpWindow" )
## active_title.gsub!( / - Opera$/, "" )

#!/usr/bin/env ruby

require 'dl/win32'
User32 = DL.dlopen("user32")

def get_activewin_title( win_class )
	# http://homepage2.nifty.com/igus/starthp/ruby_memo.html
	def get_window_text( hwnd )
		buf = "\0" * 500
		gWT = Win32API.new( 'user32', 'GetWindowTextA', 'LPI' ,'I' )
		gWT.call( hwnd,buf, buf.size )
		return buf.unpack( "A*" )[0]
	end

	def get_class_name( hwnd )
		buf = "\0" * 500
		gCN = Win32API.new( 'user32', 'GetClassName', 'LPI', 'I' )
		gCN.Call( hwnd,buf, buf.size )
		return buf.unpack( "A*" )[0]
	end
	
	hw = Win32API.new( "user32", "GetDesktopWindow", [], "L" ).call
	ec = User32['EnumChildWindows', '0LPL']
	
	activewin_title = ""
	
	enum_child_proc = DL.callback( 'IL' ) do |hwnd2|
		if activewin_title == "" and get_class_name( hwnd2 ) == win_class
			winText = get_window_text( hwnd2 )
			activewin_title = winText if winText != ""
		end
		-1
	end
	
	ec.call( hw, enum_child_proc, 0 )
	
	return activewin_title
end