Spritesmith NPM

spritesmith

Convert images into spritesheets and coordinate maps.

spritesmith is also available as:

A folder of icons processed by spritesmith:

Fork icon GitHub icon

generates a spritesheet:

spritesheet

and a coordinate map:

{
  "/home/todd/github/spritesmith/docs/fork.png": {
    "x": 0,
    "y": 0,
    "width": 32,
    "height": 32
  },
  "/home/todd/github/spritesmith/docs/github.png": {
    "x": 32,
    "y": 0,
    "width": 32,
    "height": 32
  },
  // ...
}

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Breaking changes in 2.0.0

We have moved from result.image being a binary string to it being a Buffer. This is to use more canonical conventions in Node.js.

We have moved from spritesmith-engine-spec@1.1.0 to spritesmith-engine-spec@2.0.0. This means if you use an custom engine (e.g. gmsmith, canvassmith), then you will need to upgrade it.

npm install my-engine-smith@latest --save-dev

By upgrading the engine, we added support for Vinyl objects via src as well as future-proof ourselves for forwarding streaming outputs.

Breaking changes in 3.0.0

We have updated our API to return streams for images. This required moving to a constructor and splitting apart image creation and processing.

We have maintained legacy support for spritesmith via Spritesmith.run which has an identical API to the spritesmith function in spritesmith<3.0.0.

// Before
var spritesmith = require('spritesmith');
spritesmith({src: sprites}, function handleResult (err, result) { /* ... */ });

// After
var Spritesmith = require('spritesmith');
Spritesmith.run({src: sprites}, function handleResult (err, result) { /* ... */ });

Getting started

spritesmith can be installed via npm: npm install spritesmith

// Load in dependencies
var Spritesmith = require('spritesmith');

// Generate our spritesheet
var sprites = ['fork.png', 'github.png', 'twitter.png'];
Spritesmith.run({src: sprites}, function handleResult (err, result) {
  result.image; // Buffer representation of image
  result.coordinates; // Object mapping filename to {x, y, width, height} of image
  result.properties; // Object with metadata about spritesheet {width, height}
});

Usage with streaming output

We support streaming output by breaking down run into 2 parts:

// Load in dependencies
var Spritesmith = require('spritesmith');

// Create a new spritesmith and process our images
var sprites = ['fork.png', 'github.png', 'twitter.png'];
var spritesmith = new Spritesmith();
spritesmith.createImages(sprites, function handleImages (err, images) {
  images[0].width; // Width of image
  images[0].height; // Height of image

  // Create our result
  var result = spritesmith.processImages(images);
  result.image; // Readable stream outputting image
  result.coordinates; // Object mapping filename to {x, y, width, height} of image
  result.properties; // Object with metadata about spritesheet {width, height}
});

Documentation

spritesmith exports a Spritesmith constructor as its module.exports.

If you would like a faster build time or need to support an obscure image format, see params.engine.

If you would like to adjust how images are laid out, see params.algorithm and params.algorithmOpts.

`Spritesmith.run(params, callback)`

Helper function that initializes a new Spritesmith instance, creates images, and processes them into a spritesheet

params Object - Container for parameters
- src String[]|Object[] - Same as src for spritesmith.createImages
- All other parameters accepted by new Spritesmith or processImages should be passed in here (e.g. engine, algorithm)
callback Function - Error-first function that receives compiled spritesheet and information
- callback should have signature function (err, result)
- err Error|null - If an error occurred, this will be it
- result Object - Container for result items
  - Same signature as content returned by spritesmith.processImages (i.e. {image, coordinates, properties})
  - image Buffer - In-memory representation of image
  - coordinates Object - Same as coordinates returned by spritesmith.processImages
  - properties Object - Same as properties returned by spritesmith.processImages

`new Spritesmith(params)`

Constructor for a new Spritesmith instance

params Object - Container for parameters
- engine String|Object - Optional engine override to use
  - By default we use pixelsmith, a node-based spritesmith engine
  - An example usage of engine can be found in the Examples section
  - For more engine options, see the Engines section
- engineOpts Object - Options to pass through to engine for settings
  - For example phantomjssmith accepts timeout via {engineOpts: {timeout: 10000}}
  - See your engine's documentation for available options

`spritesmith.createImages(src, callback)`

Interpret images via the spritesmith engine

src String[]|Object[] - Array of filepaths for images to include in spritesheet
- If a String is provided, then it's used as the image's filepath
- If an Object is provided, then it should be a Vinyl object pointing to the source image
  - Depending on the engine, we may/may not use the contents (e.g. gmsmith uses filepaths only)
callback Function - Error-first function that receives compiled spritesheet and map
- callback should have signature function (err, images)
- err Error|null - If an error occurred, this will be it
- images Object[] - Array of processed images
  - Each image will be a proprietary object for the engine
  - Each image will line up with the specification from spritesmith-engine-spec
  - image Object - Metadata container about corresponding input image at same index
    - height Number - Height in pixels of corresponding input image at same index
    - width Number - Width in pixels of corresponding input image at same index

`spritesheet.processImages(images, options)`

Place interpretted images on a canvas and export spritesheet

images Object[] - Images generated via spritesmith.createImages
options Object - Container for options
- padding Number - Padding to use between images
  - For example if 2 is provided, then there will be a 2px gap to the right and bottom between each image
  - An example usage of padding can be found in the Examples section
- exportOpts Mixed - Options to pass through to engine for export
  - For example gmsmith supports quality via {exportOpts: {quality: 75}}
  - See your engine's documentation for available options
- algorithm String - Optional algorithm to pack images with
  - By default we use binary-tree which packs images as efficiently as possible
  - An example usage of algorithm can be found in the Examples section
  - For more algorithm options, see the Algorithms section
- algorithmOpts Object - Optional algorithm options to pass through to algorithm for layout
  - For example top-down supports ignoring sorting via {algorithmOpts: {sort: false}}
  - See your algorithm's documentation for available options
    - https://github.com/twolfson/layout#algorithms

Returns:

result Object - Container for result information
- image ReadableStream - Readable stream outputting generated image contents
- coordinates Object - Map from filepath to coordinate information between original sprite and spritesheet
  - filepath will be the same as provided in params.src
  - filepath Object - Container for coordinate information
    - For those keeping track, this is result.coordinates[filepath]
    - x Number - Horizontal position of top-left corner of original sprite on spritesheet
    - y Number - Vertical position of top-left corner of original sprite on spritesheet
    - width Number - Width of original sprite
    - height Number - Height of original sprite
- properties Object - Container for information about spritesheet
  - width Number - Width of the spritesheet
  - height Number - Height of the spritesheet

Algorithms

Images can be laid out in different fashions depending on the algorithm. We use layout to provide you as many options as possible. At the time of writing, here are your options for params.algorithm:

`top-down`	`left-right`	`diagonal`	`alt-diagonal`	`binary-tree`

More information can be found in the layout documentation:

https://github.com/twolfson/layout

Engines

An engine can greatly improve the speed of your build (e.g. canvassmith) or support obscure image formats (e.g. gmsmith).

All spritesmith engines adhere to a common specification:

https://github.com/twolfson/spritesmith-engine-spec

This repository adheres to specification version: 2.0.0

Below is a list of known engines with their tradeoffs:

pixelsmith

pixelsmith is a node based engine that runs on top of get-pixels and save-pixels.

Key differences: Doesn't support uncommon image formats (e.g. tiff) and not as fast as a compiled library (e.g. canvassmith).

phantomjssmith

phantomjssmith is a phantomjs based engine. It was originally built to provide cross-platform compatibility but has since been succeeded by pixelsmith.

Requirements: phantomjs must be installed on your machine and on your PATH environment variable. Visit the phantomjs website for installation instructions.

Key differences: phantomjs is cross-platform and supports all image formats.

canvassmith

canvassmith is a node-canvas based engine that runs on top of Cairo.

Requirements: Cairo and node-gyp must be installed on your machine.

Instructions on how to install Cairo are provided in the node-canvas wiki.

node-gyp should be installed via npm:

npm install -g node-gyp

Key differences: canvas has the best performance (useful for over 100 sprites). However, it is UNIX only.

gmsmith

gmsmith is a gm based engine that runs on top of either Graphics Magick or Image Magick.

Requirements: Either Graphics Magick or Image Magick must be installed on your machine.

For the best results, install from the site rather than through a package manager (e.g. apt-get). This avoids potential transparency issues which have been reported.

Image Magick is implicitly discovered. However, you can explicitly use it via engineOpts

{
  engineOpts: {
    imagemagick: true
  }
}

Key differences: gmsmith allows for configuring image quality whereas others do not.

Examples

Algorithm

This is an example of using a custom layout via the alt-diagonal algorithm.

// Load in dependencies
var fs = require('fs');
var Spritesmith = require('spritesmith');

// Generate our spritesheet
Spritesmith.run({
  src: [
    __dirname + '/fork.png',
    __dirname + '/github.png',
    __dirname + '/twitter.png'
  ],
  algorithm: 'alt-diagonal'
}, function handleResult (err, result) {
  // If there was an error, throw it
  if (err) {
    throw err;
  }

  // Output the image
  fs.writeFileSync(__dirname + '/alt-diagonal.png', result.image);
  result.coordinates, result.properties; // Coordinates and properties
});

Result:

alt-diagonal spritesheet

Engine

This is an example of using a custom engine (canvassmith in this case).

// Inside package.json
{
    "dependencies": {
        "canvassmith": "~0.2.4"
    }
}

// In our script
// Load in dependencies
var fs = require('fs');
var Spritesmith = require('spritesmith');

// Generate our spritesheet
Spritesmith.run({
  src: [
    __dirname + '/fork.png',
    __dirname + '/github.png',
    __dirname + '/twitter.png'
  ],
  engine: require('canvassmith')
}, function handleResult (err, result) {
  // If there was an error, throw it
  if (err) {
    throw err;
  }

  // Output the image
  fs.writeFileSync(__dirname + '/canvassmith.png', result.image);
  result.coordinates, result.properties; // Coordinates and properties
});

Result:

canvassmith spritesheet

Padding

This is an example of adding padding between images.

// Load in dependencies
var fs = require('fs');
var Spritesmith = require('spritesmith');

// Generate our spritesheet
Spritesmith.run({
  src: [
    __dirname + '/fork.png',
    __dirname + '/github.png',
    __dirname + '/twitter.png'
  ],
  padding: 20 // Exaggerated for visibility, normally 1 or 2
}, function handleResult (err, result) {
  // If there was an error, throw it
  if (err) {
    throw err;
  }

  // Output the image
  fs.writeFileSync(__dirname + '/padding.png', result.image);
  result.coordinates, result.properties; // Coordinates and properties
});

Result:

padding spritesheet

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint via npm run lint and test via npm test.