Nasal Pathway Melodrama


    1.1.3 • Public • Published

    catage (cat to image)

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

    npm-version dependencies downloads license


    Install using NPM

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


    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 );


    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:
    Supported languages:
    Supported image formats: png,jpeg


    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



    $ catage --help
    Usage: catage [options] <inputFile> <outputFile>
    Convert code (text) file to an image file
      -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.png -l python -t "Builtin Solarized Light" --frame-title "Recursive Function" --execute="python3 __FILE__" --display-command="python"

    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


    • 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.


    This tool is dependent 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.


    npm i catage

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