Microsoft Windows Support

The three libraries documented in this chapter turn Ruby into a powerful and convenient Windows scripting language. Now you have the power to control your applications, but in a controlled, object-oriented environment.

class WIN32OLE < Object

require 'win32ole'
ie = WIN32OLE.new('InternetExplorer.Application')
ie.visible = true
ie.gohome

WIN32OLE provides a client interface to Windows 32 OLE Automation servers. See the tutorial description “Windows Automation” for more information.

WIN32OLE constants

WIN32OLE::VERSION Current version number

WIN32OLE class methods

connect: WIN32OLE.connect( aString ) → wapi; Returns a new OLE automation client connected to an existing instance of the named automation server.
const_load: WIN32OLE.const_load( wapi, [aClass=WIN32OLE] ) → nil; Defines the constants from the specified automation server as class constants in aClass.
new: WIN32OLE.new( aString ) → wapi; Returns a new OLE automation client connected to a new instance of the automation server named by aString.

WIN32OLE instance methods

[ ]: wapi[ aString ] → anObject; Returns the named property from the OLE automation object.
[ ]=: wapi[ aString ] = aValue → nil; Sets the named property in the OLE automation object.
each: wapi.each {| anObj | block } → nil; Iterates over each item of this OLE server that supports the IEnumVARIANT interface.
invoke: wapi.invoke ( aCmdString, [args]* ) → anObject; Invokes the command given in aCmdString with the given args. args may be a Hash of named parameters and values. You don't need to call invoke explicitly; this class uses method_missing to forward calls through invoke, so you can simply use the OLE methods as methods of this class.

class WIN32OLE_EVENT < Object

This (slightly modified) example from the Win32OLE 0.1.1 distribution shows the use of an event sink.

require 'win32ole'

$urls = []

def navigate(url)
  $urls << url
end

def stop_msg_loop
  puts "IE has exited..."
  throw :done
end

def default_handler(event, *args)
  case event
  when "BeforeNavigate"
    puts "Now Navigating to #{args[0]}..."
  end
end

ie = WIN32OLE.new('InternetExplorer.Application')
ie.visible = TRUE
ie.gohome
ev = WIN32OLE_EVENT.new(ie, 'DWebBrowserEvents')

ev.on_event {|*args| default_handler(*args)}
ev.on_event("NavigateComplete") {|url| navigate(url)}
ev.on_event("Quit") {|*args| stop_msg_loop}

catch(:done) {
  loop {
    WIN32OLE_EVENT.message_loop
  }
}

puts "You Navigated to the following URLs: "
$urls.each_with_index do |url, i|
  puts "(#{i+1}) #{url}"
end

WIN32OLE_EVENT is used in conjunction with the WIN32OLE class to add callbacks for Windows 32 events.

WIN32OLE_EVENT class methods

message_loop: WIN32OLE_EVENT.message_loop → nil; Executes the Windows event loop, translating and dispatching events.
new: WIN32OLE_EVENT.new ( anOle, aName ) → wapi; Returns a new WIN32OLE_EVENT (an event sink) for the given WIN32OLE object and named event source. If aName is nil, it will attempt to use the default source and will raise a RuntimeError if it cannot find one.

WIN32OLE_EVENT instance methods

on_event: wapi.on_event ( [anEvent] ) {| args | block } → nil; Defines a callback for the named anEvent. If anEvent is nil, then this callback is associated with all events. The block will be given any arguments appropriate for this event.

class Win32API < Object

This example is from the Ruby distribution, in ext/Win32API:

require 'Win32API'

getCursorPos = Win32API.new("user32", "GetCursorPos", ['P'], 'V')

lpPoint = " " * 8 # store two LONGs
getCursorPos.Call(lpPoint)
x, y = lpPoint.unpack("LL") # get the actual values

print "x: ", x, "\n"
print "y: ", y, "\n"

ods = Win32API.new("kernel32", "OutputDebugString", ['P'], 'V')
ods.Call("Hello, World\n")

GetDesktopWindow = Win32API.new("user32", "GetDesktopWindow", [], 'L')
GetActiveWindow = Win32API.new("user32", "GetActiveWindow", [], 'L')
SendMessage = Win32API.new("user32", "SendMessage", ['L'] * 4, 'L')
SendMessage.Call(GetDesktopWindow.Call, 274, 0xf140, 0)

The Win32API module allows access to any arbitrary Windows 32 function. Many of these functions take or return a Pointer datatype—a region of memory corresponding to a C string or structure type.

In Ruby, these pointers are represented using class String, which contains a sequence of 8-bit bytes. It is up to you to pack and unpack the bits in the String. See the reference sections for String#unpack and Array#pack for details.

Win32API class methods

new

Win32API.new( dllname, procname, importArray, export ) → wapi

Returns a new object representing a Windows 32 API function. dllname is the name of the DLL containing the function, such as “user32” or “kernel32.” procname is the name of the desired function. importArray is an array of strings representing the types of arguments to the function.

export is a string representing the return type of the function. Strings “n” and “l” represent numbers, “i” represent integers, “p” represents pointers to data stored in a string, and “v” represents a void type (used for export parameters only). These strings are case-insensitive.

Win32API instance methods

call: wapi.call( [args]* ) → anObject; Calls this API function with the given arguments, which must match the signature specified to new.
Call: wapi.Call( [args]* ) → anObject; Synonym for Win32API#call.

Extracted from the book "Programming Ruby - The Pragmatic Programmer's Guide"

Copyright © 2001 by Addison Wesley Longman, Inc. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/).

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