catage (cat to image)

Node package and CLI tool to convert code into image with syntax highlighting.

Install using NPM

npm install --save catage
npm install --global catage

API

const path = require( 'path' );

// import `convert` function and constants
const { convert, IMAGE_FORMATS, LANGUAGES, THEMES } = require( 'catage' );

// convert a code file to an image file
convert( options );

options

Name	Use	default Value
inputFile	Required: Relative or absolue path of a code (text) file.	undefined
outputFile	Required: Relative or absolue of the output image file.	undefined
language	Language of the code file.	LANGUAGES.DART
theme	Theme for the syntax highlighting.	THEMES.FIREWATCH
format	Format of the output image file.	IMAGE_FORMATS.PNG
ignoreLineNumbers	Avoid adding line numbers to the code.	false
scale	DPI scale factor of the output image.	2
hasFrame	Add OSX window frame in the output image.	true
execute	Execute a command with inputFile and inject result in output image file.	null
displayCommand	An alternative command to display in the output image.	execute option value

Supported themes: https://iterm2colorschemes.com/
Supported languages: https://github.com/highlightjs/highlight.js/tree/master/src/languages
Supported image formats: png,jpeg

Example

const path = require( 'path' );

// import library functions and constants
const { convert, IMAGE_FORMATS, LANGUAGES, THEMES } = require( '../' );

// create image of a code file
convert( {

    // by ignoring `outputFile` option, promise resolution will return an image buffer
    outputFile: path.resolve( __dirname, 'set-data-structure.png' ),

    inputFile: path.resolve( __dirname, 'set-data-structure.dart' ),
    language: LANGUAGES.DART,
    format: IMAGE_FORMATS.PNG,
    theme: THEMES.FIREWATCH,
    ignoreLineNumbers: false,
    scale: 2,
    hasFrame: true,
    frameTitle: 'Dart Sets Data Structure',
    execute: 'dart __FILE__', // `__FILE__` placeholder is mandatory
    displayCommand: 'dart sets.dart',
} ).then( () => {
    console.log( 'DONE!' );
} );

Output Image

CLI

$ catage --help
Usage: catage [options] <inputFile> <outputFile>

Convert code (text) file to an image file

Options:
  -v, --version                       Prints current CLI version.
  -l, --language <language>           Language of the code in the input file
  -t, --theme <theme>                 Theme for the syntax highlighting
  -f, --format <format>               Format of the output image file ( png / jpeg / jpg / svg ).
  -s, --scale <scale>                 DPI scale factor of the output image
  --no-line-numbers                   Ignore line numbers in the code
  --no-frame                          Ignore OSX window frame in the output image
  --frame-title <frameTitle>          Title of the OSX window frame
  --execute <execute>                 Command to execute with the code file. You must provide `__FILE__` placeholder in the command string.
  --display-command <displayCommand>  An alternative command to display in the output result.
  -h, --help                          output usage information

1. Example

catage recursive-function.py recursive-function.png -l python -t "Builtin Solarized Light" --frame-title "Recursive Function" --execute="python3 __FILE__" --display-command="python recursive-function.py"

Output Image

2. Simplest example

catage go-defer.go go-defer.jpg -l go -t AtomOneLight -f jpeg --no-line-numbers --no-frame

Output Image

Tricks

• If you want to take screenshot of a plain text file (no-language), provide any value to the language option that does not listed in supported languages. Since it is a plain text file, you can not use execute option. Also the code won't be syntax highlighted.
• If you are using another program to trigger catage command, then make sure your program is inheriting STDIO of the shell process which started it. This is necessary for syntax highlighting.

Warning

This tool is dependent on puppeteer NPM package which has external dependency on headless Chromium browser. After installation, puppeteer downloads Chromium browser which could be more than 100MB in zipped format.