Facing new challenges everyday

Writing MacOSX System Services with RubyCocoa

September 7th, 2009

Today I started my study about RubyCocoa and how it works, my first project was a simple system service for MacOSX Leopard where the user can type a portuguese text, select it and translate to english, the user can also type the text in english and execute the system service to translate it back to portuguese.

Here’s what I did:

1. Create XCode project

Open Xcode, go to File -> New Project… and in New Project window select Cocoa-Ruby Application as project template exactly like the image below:

2. Create the class that will handle service messages

Please click on File -> New File… to open New File window, please select Ruby NSObject subclass exactly like below:

Click on Next button, a filename will be asked, you must rename the file to Service.rb and then you can copy and paste the code below:

Services.rb:

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#Importing rubycocoa library
require 'osx/cocoa'

#Importing the library below to handle http requests
require 'open-uri'

#Importing json library
require 'json'

#Including the library below to use url_encode method
require 'erb'
include ERB::Util

#Our class must inherit from NSObject to handle service messages
class Services < OSX::NSObject
include OSX

#This is the method that will execute text translation
def translate(pboard, sourceLang, targetLang)
types = pboard.types()
pboardString = nil
#checking if the type of data in pasteboard is a string
if types.include?(NSStringPboardType) then
pboardString = pboard.stringForType(NSStringPboardType)

#If the user haven't selected anything then display a message on screen
if pboardString == nil
NSAlert::alertWithMessageText_defaultButton_alternateButton_otherButton_informativeTextWithFormat_(
"Warning!", "Ok", nil, nil, "Please select a text!").runModal()
return
end

#Encoding the pasteboard string before send it to google translator service
pboardString = url_encode(pboardString)
url = 'http://ajax.googleapis.com/ajax/services/language/translate?v=1.0&q=' + pboardString + '&langpair=' + sourceLang + '%7C' + targetLang
begin
#Calling google translator service
buffer = open(url, "Referer" => "faces.eti.br").read
#Parsing server response
result = JSON.parse(buffer)
rescue
NSAlert::alertWithMessageText_defaultButton_alternateButton_otherButton_informativeTextWithFormat_(
"Warning!", "Ok", nil, nil, "Error while calling google translator!").runModal()
return
end
#Checking server response status
if result and result['responseStatus'] == 200
pboard.declareTypes_owner([NSStringPboardType], nil)
success = pboard.setString_forType_(result['responseData']['translatedText'], NSStringPboardType)
if ! success
puts "Error while replacing PasteBoard data!"
end
end
end
return
end

#This is the method that will handle the portugueToEnglish message of ITranslate service
def portugueseToEnglish_userData_error(pboard, data, error)
translate(pboard, "pt", "en")
end
#Registering the method above as system service message handler
objc_method :portugueseToEnglish_userData_error, 'v@:@*:'

#This is the method that will handle the englishToPortuguese message of ITranslate service
def englishToPortuguese_userData_error(pboard, data, error)
translate(pboard, "en", "pt")
end
#Registering the method above as system service message handler
objc_method :englishToPortuguese_userData_error, 'v@:@*:'
end

3. Registering the system service

Once that you have created the code of your system service, it’s time to register on MacOSX, you can do it by doing small changes on rb_main.rb file exactly like below:

rb_main.rb:

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#Importing rubycocoa classes
require 'osx/cocoa'

#Imporing the code of our service provider
require 'Services'

def rb_main_init
path = OSX::NSBundle.mainBundle.resourcePath.fileSystemRepresentation
rbfiles = Dir.entries(path).select {|x| /\.rb\z/ =~ x}
rbfiles -= [ File.basename(__FILE__) ]
rbfiles.each do |path|
require( File.basename(path) )
end
end

if $0 == __FILE__ then
rb_main_init

#Initializing our service
services = Services.alloc.init

#Registering our service
OSX.NSRegisterServicesProvider(services, "ITranslate")

#Update system services registry
OSX.NSUpdateDynamicServices()

#Application initialization
OSX.NSApplicationMain(0, nil)
end

4. Changing build settings

Please do a double click on ITranslate build target exactly like in the image below:

The build settings window will be opened, please change the “Wrapper Extension” to “service”:

5. Installing the service

Just copy ITranslate.service to /Library/Services folder in MacOSX.

6. Using the service

Just finish the user session and login again, open Text Editor, type a text in english, select it and click on TextEdit -> Services -> ITranslate -> English to Portuguse, the text will be translated to portuguese.

Click here to download ITranslate.

Note: ITranslate requires json library, you can find instructions about how to download and install json library here.

Posted by rogerio | Comments (2)

2 Comments »

rogerio says
Update: A new version is available for download, there’s no need to install json library separately.

September 12th, 2009 | #
dog_race (dog_race) says
http://tinyurl.com/my6nyz
Facing new challenges everyday » Writing MacOSX System Services with RubyCocoa

December 8th, 2009 | #

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Writing MacOSX System Services with RubyCocoa

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