openmoji-spritemap-generator

This lib generates merged sprite sheets from OpenMoji emojis. A sprite sheet is an image that is composed from smaller images and where every small image has known position. Emoji sprite sheets allow web developers to build emoji pickers by reducing number of individual images from hundreds to just a few, thus making web sites and apps load quickly.

In addition to sprite sheets, this lib generates a JSON data file that contains emoji positions on the sheet. For quick development, the lib also generates an HTML image map snippet where the sheet is represented by using map and area HTML tags.

Example output

Sprite sheets, HTML snippets, and JSON position data:

• smileys-emotion.png
• smileys-emotion.html
• smileys-emotion-sample.json
• animals-nature.png
• animals-nature.html
• animals-nature-sample.json

Usage

There is two intended ways to use the generator. The first is by installing it as a Node.js module into your project and commanding it via API. The second way is more standalone, and allows you to generate sprite sheets without a host project.

Both ways require you to download the OpenMoji emojis and their associated metadata to your local machine. OpenMoji provides multiple alternative sets in different colors and sizes. Therefore it is up to you which emoji set to use. Use the following to download latest 72px wide emojis and their metadata.

$ wget https://github.com/hfg-gmuend/openmoji/releases/latest/download/openmoji-72x72-color.zip
$ wget https://github.com/hfg-gmuend/openmoji/raw/master/data/openmoji.json

Usage via API

First, install the module into your project via NPM:

$ npm install openmoji-spritemap-generator

Second, include it in your source code with the emoji metadata:

const generate = require('openmoji-spritemap-generator')
const mojis = require('openmoji.json')

Third, provide configuration object. See the API docs further below for details.

generate({
  emojis: mojis.filter(moji => moji.group === 'animals-nature'),
  emojiDir: 'openmoji-72x72-color',
  targetImagePath: 'build/animals-nature.png',
  targetHtmlPath: 'build/animals-nature.html',
  targetJsonPath: 'build/animals-nature.json',
  emojiSize: 72,
  columns: 10,
  rows: 16,
  backgroundColor: '#FFFFFF00',
  name: 'animals-nature'
}, (err) => {
  if (err) { throw err }
  console.log('Spritemap generated!')
})

Finally, admire the fresh sprite sheets under build/!

Usage as standalone project

First, clone this repository to your machine.

$ git clone <git url to this repo>
$ cd openmoji-spritemap-generator

Second, install dependencies (and the emojis, see above).

$ npm install

Third, modify the default configuration in run.js as you wish. The default behaviour will first group the emojis by their group classes and then call generate for each group separately.

Fourth, check your code for errors.

$ npm test

If code ok then run it. Multiple sprite sheets will be generated under target/.

$ npm start

Finally, see the merged sheets and image map HTML under target/.

API

generate(config, callback)

Generates a sprite sheet image, a sprite data JSON, and an image map HTML snippet. Takes in configuration object and a callback function. The callback is invoked after generation has finished and with err if an error occurred.

The configuration object config can take following options.

• emojis: An array of emoji objects originating from openmoji.json. The order defines the order in the output.
• name: A string. A unique name for this emoji set. Affects html classes and console output.
• emojiDir: A directory path to emoji images, downloaded from OpenMoji.
• targetImagePath: A file path where to save the sheet image.
• targetHtmlPath: A file path where to save the image map html snippet.
• targetJsonPath: A file path where to save the map data json.
• emojiSize: An integer. The pixel width (=height) of emojis in emojiDir. Default is 72.
• columns: An integer. How many emojis to place on a single sprite sheet row. Default is 10.
• rows: An integer. How many rows of emojis.
• backgroundColor: A string, parsed by color. Transparent by default.

Additional notes:

• If emojis provide less emojis than what could fit the columns and rows, then the remaining places are filled with the background color.
• If emojis provide more emojis than what could fit the columns and rows, then the extra emojis are left out and not rendered.
• Resizing emojis is not currently supported. You must resize the emojis beforehand and provide matching emojiSize.

Known problems

Bus error: 10

Happens at least on macOS 10.14 with Node 8.15 and Node 12.16 when there is more than 200 emojis to be merged. Cause unsure but has something to do with memory management. As a quick workaround, try to merge less emojis.

Licence

The generated sprite sheets are licensed under CC-BY-SA 4.0. The source code is licensed under MIT License.

See also

• OpenMoji.org