mdimg

A tool that can be used to convert Markdown or HTML format text to an image.

How does it work?

First, the script calls marked to parse Markdown into a HTML document. Next, use Puppeteer to start a headless browser and render the document with preset HTML and CSS files. Finally, export our image through Puppeteer's screenshot API.

Preview

HTML Template	CSS Template	Notes
Default	Default
Default	Empty	Not using any CSS presets
Default	Github
Default	Github Dark
Words	Words	It is recommended to use with plain text only

Requirements

This tool requires an LTS Node version (v12.0.0+).

Installation

CLI:

npm install -g mdimg

In Node.js project:

npm install mdimg

Usage

CLI

Example:

mdimg -i input.md -o output.png -w 600 --css github

mdimg will read text from input.md and convert it to an image file output.png.

When using the command, you must specify either -i (input file, recommended) or -t (directly input text).

When using -t to input Markdown text directly, escape characters will not be available. To fix this, for example, you should replace \n with <br>.

You can always call mdimg -h to get complete help.

In Node.js project

Import mdimg to your project:

const { convert2img } = require("mdimg");

// or use import
import { convert2img } from "mdimg";

Convert markdown text or file to image:

const convertRes = await convert2img({
  mdFile: "path/to/input.md",
  outputFilename: "path/to/output.png",
  width: 600,
  cssTemplate: "github",
});

console.log(`Convert to image successfully!\nFile: ${convertRes.data}`);

When using convert2img() method, you must specify either mdFile (input file) or mdText (directly input text).

Options:

Argument	Type	Default	Notes
mdText	`String`	`undefined`	Input Markdown or HTML text directly. This option has no effect if `mdFile` is specified
mdFile	`String`	`undefined`	Read Markdown or HTML text from a file
outputFilename	`String`	`./mdimg_output/mdimg_${new Date()}.${type}`	Output binary image filename. File type can be `jpeg`, `png` or `webp`. Available when `encoding` option is `binary`
type	`String`	`png`	The file type of the image. Type can be one of `jpeg`, `png` or `webp`, defaults to `png`. Type will be inferred from `outputFilename` if available
width	`Number`	`800`	The width of output image
encoding	`String`	`binary`	The encoding of output image. Available value can be `binary` or `base64`.
quality	`Number`	`100`	The quality of the image, between 0-100. Not applicable to `png` image.
htmlTemplate	`String`	`default`	HTML rendering template. Available templates can be found in `template/html`
cssTemplate	`String`	`default`	CSS rendering template. Available templates can be found in `template/css`
log	`Boolean`	`false`	Show preset console log
puppeteerProps	`LaunchOptions`	`undefined`	Launch options of Puppeteer

Returns: Promise<object>

Key	Value Type	Notes
data	`string` \| `Buffer`	Buffer (`encoding` is `binary`) or a BASE64 encoded string (`encoding` is `base64`) with the output image
path	`string`	The path of output iamge. Available when `encoding` is `binary`
html	`string`	The rendered HTML document

Custom template

Templates are stored in the template directory.

Now, if you run the following command:

mdimg -i input.md --html custom --css custom

The mdimg will read custom.html from template/html directory as HTML template and custom.css from template/css directory as CSS template to render the image of input.md.

HTML template

Create a new .html file in template/html directory.

There is only one rule you need to follow: an element with id mdimg-body wrapping an element with class markdown-body.

The simplest example:

<div id="mdimg-body">
  <div class="markdown-body" />
</div>

The mdimg will put the parsed HTML content in the element with class markdown-body (elements inside will be replaced), and finally generate the image for the whole element whose id is mdimg-body.

CSS template

Create a new .css file in template/css directory and then make your style!

For further development, it is recommended that write .scss or .sass files in the template/scss directory, and use the following command to generate CSS templates:

# Build .scss and .sass files
npm run rollup:sass

CSS templates with the corresponding name will be generated in template/css directory.

Development

git clone https://github.com/LolipopJ/mdimg.git
cd mdimg
yarn
# npm install

Lint

# Check .js syntax only
npm run lint
# Check and fix syntax
npm run prettier

Build

# Build .js, .scss and .sass files
npm run build

Test

# You should build before testing
# npm run build
npm run test

Inspired by

md2img. Provided me the idea and a complete feasible solution.
marked. Learned a possible method to write a JavaScript library.

inwikipedia/mdimg