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Mordant

Colorful styling for command-line applications

/mɔː(ɹ)dənt/ A substance used to set (i.e. bind) colored dyes on fabrics 1

Mordant has:

  • Easy colorful ANSI output with automatic detection of terminal capabilities
  • Markdown rendering directly to the terminal
  • Widget for laying out terminal output, including lists, tables, panels, and more
  • Support for animating any widget, like progress bars and dashboards
This README documents Mordant 2.0, which is in beta. You can read the docs for Mordant 1.0 here.

Usage

Create a Terminal instance, and import any enum entries you want from TextColors and TextStyles. The println function on your Terminal will detect your current terminal capabilities and automatically downsample ANSI codes if necessary.

import com.github.ajalt.mordant.rendering.TextColors.*
import com.github.ajalt.mordant.rendering.TextStyles.*

val t = Terminal()
t.println(red("This text will be red on terminals that support color"))

Multiple styles

import com.github.ajalt.mordant.rendering.TextColors.*
val t = Terminal()
t.println("${red("red")} ${white("white")} and ${blue("blue")}")

Foreground and background colors

t.println((yellow on brightGreen)("this is easy to read, right?"))

Background color alone

t.println("The foreground ${brightBlue.bg("color will stay the")} same")

Combine styles and colors

val style = (bold + white + underline)
t.println(style("You can save styles"))
t.println(style("to reuse"))

Nest styles and colors

t.println(white("You ${(blue on yellow)("can ${(black + strikethrough)("nest")} styles")} arbitrarily"))

True color and other color spaces

import com.github.ajalt.mordant.rendering.TextColors.Companion.rgb

t.println(rgb("#b4eeb4")("This will get downsampled on terminals that don't support truecolor"))

Terminal color support detection

By default, Terminal() will try to detect ANSI support in the current stdout stream. If you’d like to override the detection, you can pass a specific value to the Terminal constructor.

For example, to always output ANSI RGB color codes, even if stdout is currently directed to a file, you can do this:

Terminal(AnsiLevel.TRUECOLOR)

Tables

Use the table DSL to quickly create tables. Mordant handles ANSI styles and wide characters like CJK and emoji.

val t = Terminal()
t.println(table {
    header { row("CJK", "Emojis") }
    body { row("모ㄹ단ㅌ", "🙊🙉🙈") }
})

Mordant gives you lots of customization for your tables, including striped row styles, row and column spans, and different border styles.

table {
    borderStyle = SQUARE_DOUBLE_SECTION_SEPARATOR
    align = RIGHT
    outerBorder = false
    column(0) {
        align = LEFT
        borders = ALL
        style = magenta
    }
    column(3) {
        borders = ALL
        style = magenta
    }
    header {
        style(magenta, bold = true)
        row("", "Projected Cost", "Actual Cost", "Difference")
    }
    body {
        rowStyles(blue, brightBlue)
        borders = TOM_BOTTOM
        row("Food", "$400", "$200", "$200")
        row("Data", "$100", "$150", "-$50")
        row("Rent", "$800", "$800", "$0")
        row("Candles", "$0", "$3,600", "-$3,600")
        row("Utility", "$145", "$150", "-$5")
    }
    footer {
        style(bold = true)
        row {
            cell("Subtotal")
            cell("$-3,455") { columnSpan = 3 }
        }
    }
    captionBottom("Budget courtesy @dril", TextStyle(dim = true))
}

Markdown

Mordant can render GitHub Flavored Markdown. Hyperlinks will even be clickable if you’re on a terminal that supports it, like recent versions of iTerm or Windows Terminal.

val t = Terminal()
t.printMarkdown(File("README.md").readText())

Controlling the cursor

You can show and hide the cursor, move it around, and clear parts of the screen with the cursor property on Terminal. If your terminal doesn’t support cursor movements (like when output is redirected to a file) these commands are no-ops.

val t = Terminal()
t.cursor.move {
    up(3)
    startOfLine()
    clearScreenAfterCursor()
}
t.cursor.hide(showOnExit = true)

Animations

You can animate any widget like a table with Terminal.animation, or any regular string with Terminal.textAnimation.

val t = Terminal()
val a = t.textAnimation<Int> { frame ->
    (1..50).joinToString("") {
        val hue = (frame + it) * 3 % 360
        t.colors.hsv(hue, 100, 100)("━")
    }
}

t.cursor.hide(showOnExit = true)
repeat(120) {
    a.update(it)
    Thread.sleep(25)
}

Progress bars

You can create customizable progress bars that automatically compute speed and time remaining.

val t = Terminal()
val progress = t.progressAnimation {
    text("my-file.iso")
    percentage()
    progressBar()
    completed()
    speed("B/s")
    timeRemaining()
}

The progressAnimation builder is currently JVM-only. On other platforms, you can still use t.animation { progressLayout { ... } } which will render the same widget, you’ll just need to call progress.update manually.

Call progress.start to animate the progress, and progress.update or progress.advance as your task completes.

Installation

Mordant is distributed through Maven Central.

dependencies {
   implementation("com.github.ajalt.mordant:mordant:2.0.0-beta2")
}
In version 2.0, the maven coordinates changed. Make sure you’re using the new coordinates if you’re updating from an older version.
If you’re using Maven instead of Gradle, use <artifactId>mordant-jvm</artifactId>