tui-scala

tui-scala is a Scala library to build rich terminal user interfaces and dashboards. It is a port of tui-rs, which is heavily inspired by the Javascript library blessed-contrib and the Go library termui.

The port is now complete, and from here on it will diverge from the original design. See roadmap for immediate plans. There are some design/ideas tasks where you can help with ideas, POCs and implementation if you want to contribute!

The library uses crossterm as a backend. crossterm handles differences between platforms, so everything should work on major operating systems, including windows.

The integration with crossterm is published separately as a Java artifact, which calls native rust code through JNI. This integration works both when running on the JVM and when running as GraalVM native image.

The library is based on the principle of immediate rendering with intermediate buffers. This means that at each new frame you should build all widgets that are supposed to be part of the UI. While providing a great flexibility for rich and interactive UI, this may introduce overhead for highly dynamic content. So, the implementation try to minimize the number of ansi escapes sequences generated to draw the updated UI. In practice, given the speed of the JVM the overhead rather comes from the terminal emulator than the library itself.

Moreover, the library does not provide any input handling nor any event system, and you may rely on crossterm achieve such features.

Widgets

The library comes with a bunch of widgets: here is example code for all of them:

• BarChart
• Block
• Canvas
• Chart
• CustomWidget
• Gauge
• Layout
• List
• Paragraph
• Popup
• Sparkline
• Table
• Tabs
• UserInput

Click on each item to see the source of the example. Run the examples with bleep (bleep run demo@jvm213), and quit by pressing q.

The demo shown in the first video can be found here:

• Demo

Installation

For sbt:

  libraryDependencies += "com.olvind.tui" %% "tui" % "<version>"

If you only want crossterm to do low-level things, or if you want to experiment with making a TUI, these are the coordinates:

  libraryDependencies += "com.olvind.tui" % "crossterm" % "<version>"

And then copy/paste one of the demos above to get started.

It's cross published for scala 2.13 and 3. Note that scala 3 won't work with graalvm native image until 3.3.

You'll need a recent JVM with support for sealed interfaces and records. likely 18.

Contributing/building

See contributing