The JRuby community has paid a lot of attention to web development, but JRuby is also a powerful tool for client application development. By allowing the runtime to access the graphics subsystem, JRuby can be used to create GUI applications with the Abstract Windowing Toolkit (AWT), Swing and the Simple Widget Toolkit (SWT), as well as newer projects like Qt Jambi. These toolkits have a rich set of UI widgets but they also permit tight integration with the native operating system. A few recipes in this chapter explain how to use JRuby to create system tray and desktop components and access native GUI libraries.
Given the popularity of declarative programming and Ruby’s powerful Domain-Specific Language (DSL) building capabilities, it is to be expected that JRuby developers would explore ways to improve traditional Java UI programming. There are several options to facilitate Swing development: Swigby, Cheri::Swing, Monkeybars, and Profligacy. Similarly, the Glimmer Eclipse project was created for SWT and QT::JRuby has built-in DSL support.
The Rawr gem is a useful tool for packaging your JRuby applications desktop as well as the Web. This gem provides a set of Rake tasks that can be configured to package your JRuby programs as executable JAR files, Windows executables, Mac OS X applications, and Web Start applications. A recipe also describes techniques for using JRuby to build Java applets.
Image processing is one of the few areas ...