Grunt-spritely NPM

grunt-spritesmith

A Grunt 0.4 or newer task for converting a set of images into a spritesheet and corresponding CSS variables.

This package is forked from grunt-spritesmith and makes the following changes:

uses the Grunt 0.4 standard this.options and this.files instead of raw this.data. This is adventageous for using this task together with grunt-newer.
adds the option mapSrcToName and mapDestImageToUrl. mapDestImageToUrl replaces the imgPath option.

A folder of icons processed by grunt-spritesmith:

generates a spritesheet:

and CSS variables (available in CSS, JSON, SASS, SCSS, LESS, Stylus):

$fork_offset_x = 0px;
$fork_offset_y = 0px;
$fork_width = 32px;
$fork_height = 32px;
...
$github_offset_x = -32px;
$github_offset_y = 0px;
$github_width = 32px;
$github_height = 32px;
...

Cross-platform support

grunt-spritesmith is supported and tested on Windows, Linux, and Mac OSX.

Getting Started

grunt-spritesmith can be installed via npm: npm install grunt-spritesmith

Before proceeding, verify you have satisfied your preferred engine's requirements.

Then, add and configure it to your grunt file (grunt.js or Gruntfile.js depending on your version):

module.exports = function (grunt) {
  // Configure grunt
  grunt.initConfig({
    sprite:{
      all: {
        src: 'path/to/your/sprites/*.png',
        destImg: 'destination/of/spritesheet.png',
        destCSS: 'destination/of/sprites.css'
      }
    }
  });

  // Load in `grunt-spritesmith`
  grunt.loadNpmTasks('grunt-spritesmith');

Run the grunt sprite task:

$ grunt sprite
Running "sprite:all" (sprite) task
Files "spritesheet.png", "sprites.styl" created.

Done, without errors.

Results are a spritesheet and CSS:

.icon-fork {
  background-image: url(spritesheet.png);
  background-position: 0px 0px;
  width: 32px;
  height: 32px;
}
...

Usage

grunt-spritesmith is a grunt multitask. It is configured on a per-task basis using the following template:

grunt.initConfig({
  'sprite': {
    'all': {
      // Sprite files to read in
      'src': ['public/images/sprites/*.png'],

      // Location of the image to output
      'dest': 'public/images/sprite.png',

      'options': {
        // Stylus with variables under sprite names
        'destCSS': 'public/css/sprite_positions.styl',

        // OPTIONAL: Transform the input image file name to the identifier used for the sprite.
        'mapSrcToName': 2,

        // OPTIONAL: Transform the output image file into a URL
        'mapDestImageToUrl': 2,

        // OPTIONAL: Specify algorithm (top-down, left-right, diagonal [\ format],
            // alt-diagonal [/ format], binary-tree [best packing])
        // Visual representations can be found below
        'algorithm': 'alt-diagonal',

        // OPTIONAL: Specify padding between images
        'padding': 2,

        // OPTIONAL: Specify engine (auto, phantomjs, canvas, gm)
        'engine': 'canvas',

        // OPTIONAL: Specify CSS format (inferred from destCSS' extension by default)
            // (stylus, scss, sass, less, json, jsonArray, css)
        'cssFormat': 'json',

        // OPTIONAL: Specify a Mustache template to use for destCSS; mutually exclusive to cssFormat
        'cssTemplate': 'public/css/sprite_positions.styl.mustache',

        // OPTIONAL: Map variable of each sprite
        'cssVarMap': function (sprite) {
          // `sprite` has `name`, `image` (full path), `x`, `y`
          //   `width`, `height`, `total_width`, `total_height`
          // EXAMPLE: Prefix all sprite names with 'sprite-'
          sprite.name = 'sprite-' + sprite.name;
        },

        // OPTIONAL: Specify settings for engine
        'engineOpts': {
          'imagemagick': true
        },

        // OPTIONAL: Specify img options
        'imgOpts': {
           // Format of the image (inferred from destImg' extension by default) (jpg, png)
           'format': 'png',

           // Quality of image (gm only)
           'quality': 90
        },

        // OPTIONAL: Specify css options
        'cssOpts': {
          // Some templates allow for skipping of function declarations
          'functions': false,

          // CSS template allows for overriding of CSS selectors
          'cssClass': function (item) {
            return '.sprite-' + item.name;
          }
        }
      }
    }
  }
});

Specifying files

Files may be specified using several different grunt-standard formats described here: http://gruntjs.com/configuring-tasks#files. For example:

New configuration examples

One sheet

sprite:{
  all: {
    options: {
      destCSS: 'destination/of/sprites.css'
    },
    src: 'path/to/your/sprites/*.png',
    dest: 'destination/of/spritesheet.png'
  }
}

Multiple sheets

sprite:{
  all: {
    options: {
      destCSS: 'destination/of/sprites.css'
    },
    files: [
      {
        src: 'path/to/your/sprites/core/*@1x.png',
        dest: 'destination/of/core@1x.png',
      },
      {
        src: 'path/to/your/sprites/core/*@2.png',
        dest: 'destination/of/core@2x.png',
      },
      {
        src: 'path/to/your/sprites/detail-page/*@1x.png',
        dest: 'destination/of/detail-page@1x.png',
      },
      {
        src: 'path/to/your/sprites/detail-page/*@2x.png',
        dest: 'destination/of/detail-page@2x.png',
      }
    ]
  }
}

Algorithms

top-down (default)	left-right	diagonal	alt-diagonal	binary-tree

For best packing, use binary-tree which uses a solution to the rectangle packing problem.

If you are worried about sprites being visible within other sprites, use alt-diagonal.

If you are using a repeating background, top-down or left-right depending on your occasion.

The diagonal algorithm exists for you if you need it.

Requirements

For cross-platform accessibility, spritesmith has and supports multiple sprite engines. However, each of these current engines has a different set of external dependencies.

If you are running into issues, consult the FAQ section.

phantomjs

The phantomjs engine relies on having phantomjs installed on your machine. Visit the phantomjs website for installation instructions.

Key differences: phantomjs is the most accessible engine.

spritesmith has been tested against phantomjs@1.9.0.

canvas

The canvas engine uses node-canvas which has a dependency on Cairo.

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

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

Additionally, you will need to install node-gyp for the C++ bindings.

sudo npm install -g node-gyp

gm (Graphics Magick / Image Magick)

The gm engine depends on Graphics Magick or Image Magick.

Key differences: gm has the most options for export via imgOpts.

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.

spritesmith has been developed and tested against 1.3.17.

If you are using Image Magick, you must specify it in engineOpts

{
  'engineOpts': {
    'imagemagick': true
  }
}

FAQs

I am seeing errors during installation.

If npm exits normally, everything should work. These errors are being caused by npm attempting to install the various spritesmith engines.

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 grunt and test via npm test.