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GOCUI - Go Console User Interface

Minimalist Go package aimed at creating Console User Interfaces. A community fork based on the amazing work of jroimartin For v0 to v1 mirgration help read: migrate-to-v1.md

Features

Minimalist API.
Views (the "windows" in the GUI) implement the interface io.ReadWriter.
Support for overlapping views.
The GUI can be modified at runtime (concurrent-safe).
Global and view-level keybindings.
Mouse support.
Colored text.
Customizable editing mode.
Easy to build reusable widgets, complex layouts...

About fork

This fork has many improvements over the original work from jroimartin.

Written ontop of TCell
Better wide character support
Support for 1 Line height views
Support for running in docker container
Better cursor handling
Customize frame colors
Improved code comments and quality
Many small improvements
Change Visibility of views
Requires Go 1.13 or newer

For information about this org see: awesome-gocui/about.

Installation

Execute:

$ go get github.com/awesome-gocui/gocui

Documentation

Execute:

$ go doc github.com/awesome-gocui/gocui

Or visit godoc.org to read it online.

Example

See the _example folder for more examples

package main

import (
	"fmt"
	"log"

	"github.com/awesome-gocui/gocui"
)

func main() {
	g, err := gocui.NewGui(gocui.OutputNormal, true)
	if err != nil {
		log.Panicln(err)
	}
	defer g.Close()

	g.SetManagerFunc(layout)

	if err := g.SetKeybinding("", gocui.KeyCtrlC, gocui.ModNone, quit); err != nil {
		log.Panicln(err)
	}

	if err := g.MainLoop(); err != nil && !errors.Is(err, gocui.ErrQuit) {
		log.Panicln(err)
	}
}

func layout(g *gocui.Gui) error {
	maxX, maxY := g.Size()
	if v, err := g.SetView("hello", maxX/2-7, maxY/2, maxX/2+7, maxY/2+2, 0); err != nil {
		if !errors.Is(err, gocui.ErrUnknownView) {
			return err
		}

		if _, err := g.SetCurrentView("hello"); err != nil {
			return err
		}

		fmt.Fprintln(v, "Hello world!")
	}

	return nil
}

func quit(g *gocui.Gui, v *gocui.View) error {
	return gocui.ErrQuit
}

Testing example

You can write simple tests for gocui which let you simulate keyboard and then validate the output drawn to the screen.

Create an instance of gui with OutputSimulator set as the mode g, err := NewGui(OutputSimulator, true)
Call GetTestingScreen to get a testingScreen instance.
On this you can use SendKey to simulate input and GetViewContent to evaluate what is drawn.

Warning: Timing plays a part here, key bindings don't fire synchronously and drawing isn't instant. Here we used time.After to pause, gomega's asynchronous assertions are likely a better alternative for more complex tests.

Here is a simple example showing how this can be used to validate what a view shows and that a key binding is handled correctly:

func TestTestingScreenReturnsCorrectContent(t *testing.T) {
	// Track what happened in the view, we'll assert on these
	didCallCTRLC := false
	expectedViewContent := "Hello world!"
	viewName := "testView1"

	// Create a view specifying the "OutputSimulator" mode
	g, err := NewGui(OutputSimulator, true)
	if err != nil {
		log.Panicln(err)
	}
	g.SetManagerFunc(func(g *Gui) error {
		maxX, maxY := g.Size()
		if v, err := g.SetView(viewName, maxX/2-7, maxY/2, maxX/2+7, maxY/2+2, 0); err != nil {
			if !errors.Is(err, ErrUnknownView) {
				return err
			}

			if _, err := g.SetCurrentView(viewName); err != nil {
				return err
			}

			// Have the view draw "Hello world!"
			fmt.Fprintln(v, expectedViewContent)
		}

		return nil
	})

	// Create a key binding which sets "didCallCTRLC" when triggered
	exampleBindingToTest := func(g *Gui, v *View) error {
		didCallCTRLC = true
		return nil
	}
	if err := g.SetKeybinding("", KeyCtrlC, ModNone, exampleBindingToTest); err != nil {
		log.Panicln(err)
	}

	// Create a test screen and start gocui
	testingScreen := g.GetTestingScreen()
	cleanup := testingScreen.StartGui()
	defer cleanup()

	// Send a key to gocui
	testingScreen.SendKey(KeyCtrlC)

	// Wait for key to be processed
	<-time.After(time.Millisecond * 50)

	// Test that the keybinding fired and set "didCallCTRLC" to true
	if !didCallCTRLC {
		t.Error("Expect the simulator to invoke the key handler for CTRLC")
	}

	// Get the content from the testing screen
	actualContent, err := testingScreen.GetViewContent(viewName)
	if err != nil {
		t.Error(err)
	}

	// Test that it contains the "Hello World!" we thought the view should draw
	if strings.TrimSpace(actualContent) != expectedViewContent {
		t.Error(fmt.Printf("Expected view content to be: %q got: %q", expectedViewContent, actualContent))
	}
}

Note: Under the covers this is using the tcell SimulationScreen.

Screenshots

Projects using gocui

omnivore: Distributed SSH commands with output matching.
komanda-cli: IRC Client For Developers.
vuls: Agentless vulnerability scanner for Linux/FreeBSD.
wuzz: Interactive cli tool for HTTP inspection.
httplab: Interactive web server.
domainr: Tool that checks the availability of domains based on keywords.
gotime: Time tracker for projects and tasks.
claws: Interactive command line client for testing websockets.
terminews: Terminal based RSS reader.
diagram: Tool to convert ascii arts into hand drawn diagrams.
pody: CLI app to manage Pods in a Kubernetes cluster.
kubexp: Kubernetes client.
kcli: Tool for inspecting kafka topics/partitions/messages.
fac: git merge conflict resolver
jsonui: Interactive JSON explorer for your terminal.
cointop: Interactive terminal based UI application for tracking cryptocurrencies.
lazygit: simple terminal UI for git commands.
lazydocker: The lazier way to manage everything docker.