Interphase - a powerful, easy-to-use, native-looking GUI library for Ruby

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What is Interphase?

Interphase is a GUI library for Ruby. It's got plenty of features & great cross-platform support, and it's really easy to use.

Check out this 'Hello, world' example:

require 'interphase'
include Interphase

window ='Hello world window') do
  size 200, 200

  add'Hello, world!')


Quick start

First, install the Interphase gem:

gem install interphase

In the future, Interphase will have tutorials, but for now, check out the documentation.

More info

Interphase is effectively a 'friendly wrapper' for GTK2, so it supports a plethora of widgets which look great on any platform.

Threading isn't an issue either; one simple in_background call creates a Thread and binds it to a window, killing the thread when the window is closed.

window = do
  in_background do
    # A long-running task

Interphase also uses a novel widget naming system based on keyword arguments. Every widget may be assigned a name: keyword argument in its constructor. It is bound by this name to its container, through which it may be referenced later.

window = do
  add'Hello', name: 'my_label')

window.my_label.text = 'Hello again'

Events (called 'signals' in GTK) can be handled using the on method, which registers a block to run when a signal occurs. The signals in Interphase are the same as those in GTK2. Some important signals, such as delete-event for a Window, also have their own on_... methods.

# These are equivalent
window.on('delete-event') do

window.on_delete do

Using layouts

The Layout widget is a powerful feature of Interphase which allows complex grid-based layouts to be templated using only a single string. One of these strings is called a layout description string, or LDS.

How an LDS works is best demonstrated using an example. Take the following LDS:


This string is two lines by three columns, so it denotes a grid with two rows and three columns. The first row contains a three-column-wide widget named a. The second row contains a two-column-wide widget named b, and then a single-column-wide widget named c. Each sequence of the same letter is called a slot.

Once a Layout has been created from this LDS, each slot may be assigned a widget using hash access syntax.

layout ='
') do
  self['a'] ='A')
  self['b'] ='B')
  self['c'] ='C')

That layout placed into a Window looks like this:

Layout Example

How does Interphase work?

Interphase components, formerly 'widgets', derive from the Widget class. Each instance maintains an instance variable named @gtk_instance, which is what is actually rendered. Most of the methods on Widget subclasses actually mutate the underlying @gtk_instance.

Widgets accept a block in their constructor which is evaluated on the new widget. In practice, this means that the following two code snippets are equivalent; the second style is encouraged over the first:

window =
window.size(800, 600)
window = do
  size 800, 600

Why GTK2?

There are plenty of GUI frameworks already, but Interphase is based on GTK2 for a variety of reasons:

  • Easy to set up. On most systems, the whole GTK2 framework can be installed using gem. I aimed for no fiddling around with DLLs or installers, ruling out Qt.
  • Looks native out of the box. The user or developer doesn't need to apply a theme to every window for it to look OS-native. Manual theming is required in GTK3, making it unsuitable for Interphase.
  • Actively supported in Ruby. wxWidgets is fantastic, and would've been ideal for this project, but its Ruby gem is unmaintained.
  • Powerful. Plenty of widgets are already implemented, and can be expanded upon easily. This is where Tk fell short.

Why not just use the gtk2 gem directly?

  • Slightly archaic API. The API feels like a direct C++ port, and as such isn't very Ruby-like.
  • Overcomplicated data structures. Creating a list box in GTK2 involves creating a special ListStore instance and inserting items into it using pointer objects. Interphase does all of this for you by monitoring changes to a simple Array of items instead.
  • Lack of high-quality tutorials. Interphase's official documentation will eventually have plenty of tutorials for both beginners and advanced users.

Where does Interphase fall short?

Nothing's perfect!

  • It's easy, but not the easiest. Interphase aims to steer clear of the DSL-esque nature of some other GUI libraries, such as Shoes. While this may make Interphase not the simplest GUI library, it can make the API feel much more robust.
  • It's new. It's untested. It doesn't have much documentation yet. Compared to the 'big ones' like Qt, Interphase has very little recognition, and as such you may find it difficult to get help on sites like Stack Overflow if you run into problems. Feel free to ask on our Discord though - see the top of the page.


  • Labels
  • Fixed containers
  • Box containers
  • Grid containers
  • Buttons
  • Form controls (e.g. dropdowns, input boxes, date pickers)
  • Toolbars and tool button strips
  • Menus
  • Images
  • Text dialog boxes
  • Input dialog boxes
  • Other dialog boxes (e.g. file chooser, print)
  • List views
  • Tree views
  • Status bars
  • Tab views
  • Custom on_... events for all common signals
  • Pages - easily interchangable window contents
  • Easy implementation of custom controls