grunt-spritesmith

Grunt task for converting a set of images into a spritesheet and corresponding CSS variables.

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;
...

Retina support

As of grunt-spritesmith@4.5.0, retina spritesheets/templates are supported. See the Retina parameters section for more information.

Cross-platform support

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

Do you like grunt-spritesmith?

Support us via donations or spread word on Twitter

Breaking changes in 5.0.0

We are normalizing sprite variables even further to convert any non-alphanumeric/non-dash/non-underscore character to a delimiter character (e.g. -). This allows us to support naming retina sprites with @2x suffixes, to prevent regressions like #137.

Breaking changes in 6.0.0

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

This is to enable usage of streaming outputs from engines.

Getting Started

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

Then, add and configure it to your Gruntfile.js:

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

Documentation

grunt-spritesmith is a grunt multitask. It supports the following parameters:

• src String|String[] - Images to use as sprites in spritesheet
  • For example this can be a glob, sprites/*.png or an array of files ['sprite1.png', sprite2.png']
• dest String - Output location for generated spritesheet
  • For example path/to/output/spritesheet.png
• destCss String - Output location for generated CSS
  • For example path/to/output/sprites.css
• imgPath String - Optional override for spritesheet path specified in CSS
  • For example if ../sprite.png is given, then the CSS will have:
    • background-image: url(../sprite.png);
• padding Number - Padding to place to right and bottom between sprites
  • By default there is no padding
  • An example usage can be found in the Examples section
• algorithm String - Algorithm to use for positioning sprites in spritesheet
  • By default this is binary-tree which yields the best possible packing
  • An example usage can be found in the Examples section
  • For more algorithm options, see the Algorithms section
• algorithmOpts Mixed - Options to pass through to algorithm
  • For example we can skip sorting in some algorithms via {algorithmOpts: {sort: false}}
    • This is useful for sprite animations
  • See your algorithm's documentation for available options
    • https://github.com/twolfson/layout#algorithms
• engine String - spritesmith engine to use
  • By default this is pixelsmith, a node based engine
  • Alternative engines must be installed via npm install
  • An example usage 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
• imgOpts Object - Options to pass through to engine uring export
  • For example gmsmith supports quality via {imgOpts: {quality: 75}}
  • See your engine's documentation for available options
• cssFormat String - CSS format to use
  • By default this is the format inferred by destCss' extension
    • For example .styl -> stylus
  • For more format options, see our formatting library
    • https://github.com/twolfson/spritesheet-templates#templates
• cssTemplate String|Function - CSS template to use for rendering output CSS
  • This overrides cssFormat
  • If a String is provided, it must be a path to a handlebars template
    • An example usage can be found in the Examples section
  • If a Function is provided, it must have a signature of function (data)
    • An example usage can be found in the Examples section
  • For more templating information, see the Templating section
• cssHandlebarsHelpers Object - Container for helpers to register to handlebars for our template
  • Each key-value pair is the name of a handlebars helper corresponding to its function
  • For example, {half: function (num) { return num/2; } will add a handlebars helper that halves numbers
• cssVarMap Function - Mapping function for each filename to CSS variable
  • For more information, see Variable mapping
• cssSpritesheetName String - Name to use for spritesheet related variables in preprocessor templates
• cssOpts Object - Options to pass through to templater
  • For example {cssOpts: {functions: false}} skips output of mixins
  • See your template's documentation for available options
    • https://github.com/twolfson/spritesheet-templates#templates

Retina parameters

grunt-spritesmith supports retina spritesheet generation via retinaSrcFilter and retinaDest. If at least one of these is provided, then we will expect the other and enable retina spritesheet generation.

Repeated parameters have the same properties as above but are repeated for clarity with respect to retina spritesheets.

An example retina spritesheet setup can be found in the Examples section.

• src String|String[] - Images to use for both normal and retina spritesheet
  • For example sprites/*.png should capture sprite1.png and [e-mail]
  • These must be ordered such that when the retina images are filtered into a separate array, the normal and retina images will have the same indices
  • We strongly encourage using the @2x suffix over -retina or -2x. There are known ordering issues caused when sharing a - delimiter between sprite names and the retina suffix (see #137)
• retinaSrcFilter String|String[] - Images to filter out from src for our retina spritesheet
  • This can be a glob as with src (e.g. sprite/*@2x.png)
  • The path/glob used should line up with src (e.g. src: 'sprite/*.png', retinaSrcFilter: 'sprite/*@2x.png')
  • For example sprites/*@2x.png will filter out [e-mail] for a separate retina spritesheet
    • Under the hood, we will group sprite1.png and [e-mail] as a group of normal/retina sprites
• retinaDest String - Output location for generated retina spritesheet
  • For example path/to/[e-mail]
• retinaImgPath - Optional override for retina spritesheet path specified in CSS
  • For example ../[e-mail] will yield CSS with:
    • background-image: url(../[e-mail]);
• padding Number - Padding to place to right and bottom between sprites
  • By default there is no padding
  • In retina spritesheets, this number will be doubled to maintain perspective
• cssFormat String - CSS format to use
  • By default this is the format inferred by destCss' extension
    • For example .styl -> stylus_retina
  • For more format options, see our formatting library
    • https://github.com/twolfson/spritesheet-templates#retina-templates
• cssVarMap Function - Mapping function for each filename to CSS variable
  • This will run through normal and retina spritesheets
  • The name used for normal sprites dictates the group name for retina group variables (e.g. $icon-home will have group $icon-home-group)
  • For more information, see Variable mapping
• cssRetinaSpritesheetName String - Name to use for retina spritesheet related variables in preprocessor templates
• cssRetinaGroupsName String - Name to use for retina groups related variables in preprocessor templates

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 algorithm:

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

More information can be found in the layout documentation:

https://github.com/twolfson/layout

Templating

The cssTemplate option allows for using a custom template. An example template can be found at:

https://github.com/twolfson/spritesheet-templates/blob/9.3.1/lib/templates/stylus.template.handlebars

The parameters passed into your template are known as data. We add some normalized properties via spritesheet-templates for your convenience.

• data Object Container for parameters
  • sprites Object[] - Array of sprite information
    • name String - Name of the sprite file (sans extension)
    • x Number - Horizontal position of sprite's left edge in spritesheet
    • y Number - Vertical position of sprite's top edge in spritesheet
    • width Number - Width of sprite
    • height Number - Height of sprite
    • total_width Number - Width of entire spritesheet
    • total_height Number - Height of entire spritesheet
    • image String - Relative URL path from CSS to spritesheet
    • escaped_image String - URL encoded image
    • source_image String - Path to the original sprite file
    • offset_x Number - Negative value of x. Useful to background-position
    • offset_y Number - Negative value of y. Useful to background-position
    • px Object - Container for numeric values including px
      • x String - x suffixed with px
      • y String - y suffixed with px
      • width String - width suffixed with px
      • height String - height suffixed with px
      • total_width String - total_width suffixed with px
      • total_height String - total_height suffixed with px
      • offset_x String - offset_x suffixed with px
      • offset_y String - offset_y suffixed with px
  • spritesheet Object - Information about spritesheet
    • width Number - Width of entire spritesheet
    • total_height Number - Height of entire spritesheet
    • image String - Relative URL path from CSS to spritesheet
    • escaped_image String - URL encoded image
    • px Object - Container for numeric values including px
      • width String - width suffixed with px
      • height String - height suffixed with px
  • spritesheet_info Object - Container for spritesheet metadata and its representation
    • name String - Prefix for spritesheet variables
  • retina_sprites Object[] - Array of retina sprite information
    • This will only be accessible if we are generating a retina spritesheet
    • Properties are the same as sprites (e.g. name, width, source_image)
  • retina_spritesheet Object - Information about retina spritesheet
    • This will only be accessible if we are generating a retina spritesheet
    • Properties are the same as spritesheet (e.g. width, px)
  • retina_spritesheet_info Object - Container for retina_spritesheet metadata and its representation
    • This will only be accessible if we are generating a retina spritesheet
    • name String - Prefix for spritesheet variables
  • retina_groups Object[] - Array of objects that maps to normal and retina sprites
    • This will only be accessible if we are generating a retina spritesheet
    • • Object - Container for data about sprite mapping
        • name String - Name to refer to mapping by
        • index Number - Index of corresponding normal/retina sprites from data.sprites/data.retina_sprites
        • normal Object - Normal sprite from data.sprites that corresponds to our mapping
          • This has all the same properties as data.sprites[*] (e.g. name, x, offset_y, px)
        • retina Object - Retina sprite from data.retina_sprites that corresponds to our mapping
          • This has all the same properties as data.retina_sprites[*] (e.g. name, x, offset_y, px)
  • retina_groups_info Object - Optional container for metadata about retina_groups and its representation
    • This will only be accessible if we are generating a retina spritesheet
    • name String - Name for retina_groups
  • options Object - Options passed in via cssOpts in grunt-spritesmith config

An example sprite is

{
  "name": "sprite2",
  "x": 10,
  "y": 20,
  "width": 20,
  "height": 30,
  "total_width": 80,
  "total_height": 100,
  "image": "nested/dir/spritesheet.png",
  "escaped_image": "nested/dir/spritesheet.png",
  "source_image": "path/to/original/sprite.png",
  "offset_x": -10,
  "offset_y": -20,
  "px": {
    "x": "10px",
    "y": "20px",
    "width": "20px",
    "height": "30px",
    "total_width": "80px",
    "total_height": "100px",
    "offset_x": "-10px",
    "offset_y": "-20px"
  }
}

If you are defining a Handlebars template, then you can inherit from an existing template via handlebars-layouts (e.g. {{#extend "scss"}}). An example usage can be found in the Examples section.

Example usages can be found as:

• Handlebars template
• Handlebars inheritance
• Template function

Variable mapping

The cssVarMap option allows customization of the CSS variable names

If you would like to customize CSS selectors in the css template, please see https://github.com/twolfson/spritesheet-templates#css

Your cssVarMap should be a function with the signature function (sprite). It will receive the same parameters as sprites from Templating except for escaped_image, offset_x, offset_y, and px.

// Prefix all sprite names with `sprite-` (e.g. `home` -> `sprite-home`)
cssVarMap: function (sprite) {
  sprite.name = 'sprite_' + sprite.name;
}

// Generates:
// $sprite_fork_x = 0px;
// $sprite_fork_y = 0px;

// As oppposed to default:
// $fork_x = 0px;
// $fork_y = 0px;

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

In this example, we will use the alt-diagonal algorithm to layout sprites in a non-intersecting manner.

Configuration:

{
  src: ['fork.png', 'github.png', 'twitter.png'],
  dest: 'spritesheet.algorithm.png',
  destCss: 'spritesheet.algorithm.styl',
  algorithm: 'alt-diagonal'
}

Output:

Engine

In this example, we will use the gmsmith engine to support obscure image formats.

Requirements:

Install gmsmith to our node_modules via npm install.

npm install gmsmith

Alternatively, we can use --save or --save-dev to save to our package.json's dependencies or devDependenices.

npm install gmsmith --save  # Updates {"dependencies": {"gmsmith": "1.2.3"}}
npm install gmsmith --save-dev  # Updates {"devDependencies": {"gmsmith": "1.2.3"}}

Configuration:

{
  src: ['fork.png', 'github.png', 'twitter.png'],
  dest: 'spritesheet.algorithm.png',
  destCss: 'spritesheet.algorithm.styl',
  engine: 'gmsmith'
}

Output:

Padding

The padding option allows for inserting spacing between images.

Configuration:

{
  src: ['fork.png', 'github.png', 'twitter.png'],
  dest: 'spritesheet.padding.png',
  destCss: 'spritesheet.padding.styl',
  padding: 20 // Exaggerated for visibility, normal usage is 1 or 2
}

Output:

Retina spritesheet

In this example, we will use generate a normal and retina spritesheet via the retinaSrcFilter and retinaDest parameters.

Configuration:

{
  // We have `fork.png`, `[e-mail]`, ...
  src: ['fork*.png', 'github*.png', 'twitter*.png'],
  // This will filter out `[e-mail]`, `[e-mail]`, ... for our retina spritesheet
  //   The normal spritesheet will now receive `fork.png`, `github.png`, ...
  retinaSrcFilter: ['*@2x.png'],
  dest: 'spritesheet.retina.png',
  retinaDest: '[e-mail]',
  destCss: 'spritesheet.retina.styl'
}

Normal spritesheet:

Retina spritesheet:

Handlebars template

In this example, we will use cssTemplate with a handlebars template to generate CSS that uses :before selectors.

Template:

{{#sprites}}
.icon-{{name}}:before {
  display: block;
  background-image: url({{{escaped_image}}});
  background-position: {{px.offset_x}} {{px.offset_y}};
  width: {{px.width}};
  height: {{px.height}};
}
{{/sprites}}

Configuration:

{
  src: ['fork.png', 'github.png', 'twitter.png'],
  dest: 'spritesheet.handlebarsStr.png',
  destCss: 'spritesheet.handlebarsStr.css',
  cssTemplate: 'handlebarsStr.css.handlebars'
}

Output:

.icon-fork:before {
  display: block;
  background-image: url(spritesheet.handlebarsStr.png);
  background-position: 0px 0px;
  width: 32px;
  height: 32px;
}
.icon-github:before {
/* ... */

Handlebars inheritance

In this example, we will extend the SCSS template to provide minimal variables. The JSON at the front comes from the original template and is required to provide consistent casing and default options.

Different block sections for each template are documented in:

https://github.com/twolfson/spritesheet-templates

Template:

{
  // Default options
  'functions': true,
  'variableNameTransforms': ['dasherize']
}

{{#extend "scss"}}
{{#content "sprites"}}
{{#each sprites}}
${{strings.name}}: ({{px.x}}, {{px.y}}, {{px.offset_x}}, {{px.offset_y}}, {{px.width}}, {{px.height}}, {{px.total_width}}, {{px.total_height}}, '{{{escaped_image}}}', '{{name}}', );
{{/each}}
{{/content}}
{{#content "spritesheet"}}
${{spritesheet_info.strings.name_sprites}}: ({{#each sprites}}${{strings.name}}, {{/each}});
${{spritesheet_info.strings.name}}: ({{spritesheet.px.width}}, {{spritesheet.px.height}}, '{{{spritesheet.escaped_image}}}', ${{spritesheet_info.strings.name_sprites}}, );
{{/content}}
{{/extend}}

Configuration:

{
  src: ['fork.png', 'github.png', 'twitter.png'],
  dest: 'spritesheet.handlebarsInheritance.png',
  destCss: 'spritesheet.handlebarsInheritance.css',
  cssTemplate: 'handlebarsInheritance.scss.handlebars'
}

Output:

$fork: (0px, 0px, 0px, 0px, 32px, 32px, 64px, 64px, 'spritesheet.handlebarsInheritance.png', 'fork', );
$github: (32px, 0px, -32px, 0px, 32px, 32px, 64px, 64px, 'spritesheet.handlebarsInheritance.png', 'github', );
$twitter: (0px, 32px, 0px, -32px, 32px, 32px, 64px, 64px, 'spritesheet.handlebarsInheritance.png', 'twitter', );
$spritesheet-sprites: ($fork, $github, $twitter, );
$spritesheet: (64px, 64px, 'spritesheet.handlebarsInheritance.png', $spritesheet-sprites, );
/* ... */

Template function

In this example, we will use cssTemplate with a custom function that generates YAML.

Configuration:

// var yaml = require('js-yaml');
{
  src: ['fork.png', 'github.png', 'twitter.png'],
  dest: 'spritesheet.yamlTemplate.png',
  destCss: 'spritesheet.yamlTemplate.yml',
  cssTemplate: function (data) {
    // Convert sprites from an array into an object
    var spriteObj = {};
    data.sprites.forEach(function (sprite) {
      // Grab the name and store the sprite under it
      var name = sprite.name;
      spriteObj[name] = sprite;

      // Delete the name from the sprite
      delete sprite.name;
    });

    // Return stringified spriteObj
    return yaml.safeDump(spriteObj);
  }
}

Output:

fork:
  x: 0
  "y": 0
  width: 32
  height: 32
  source_image: fork.png
  image: spritesheet.yamlTemplate.png
  total_width: 64
  total_height: 64
  escaped_image: spritesheet.yamlTemplate.png
  offset_x: -0.0
  offset_y: -0.0
  px:
    x: 0px
    "y": 0px
    offset_x: 0px
    offset_y: 0px
    height: 32px
    width: 32px
    total_height: 64px
    total_width: 64px
github:
  x: 32
  # ...

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.

Attribution

GitHub and Twitter icons were taken from Alex Peattie's JustVector Social Icons.

Fork designed by P.J. Onori from The Noun Project

Plus and Equals icons were built using the Ubuntu Light typeface.

License

Copyright (c) 2012 Todd Wolfson

Licensed under the MIT license.