generate css sprites automagically (A WORK IN PROGRESS)
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Rakefile Tweaking Readme and gemspec Nov 18, 2009


sprite is a gem that helps generate css sprite images automagically. It's aim is to support all web frameworks (Merb/Rails/Sinatra), and have extensible output generator. By default, it supports CSS and SASS output (via mixins).


Install the rmagick gem

sprite currently requires the rmagick gem. to install it, use

gem install rmagick

if you have any problems with the rmagick gem, install imagemagick via macports first:

sudo port install libxml2
sudo port install ImageMagick  

or via installer:

Install the sprite gem

Install the sprite gem from gemcutter

gem sources -a
gem install sprite


if installed as a gem, at your root project folder you can just run


Intelligent Defaults

Without having to configure anything, sprite will allow you to easily generate sprites based on a couple default folder settings we give you right off the bat.

For example, given you have the following setup:


Running sprite with no configuration file will generate the following new files:


Any folders within public/images/sprites/ will get compressed into a merged image file at the same location. Then sprites.css will get generated in the stylesheets folder with all the class definitions for these files. Just add a link to sprites.css into your html and you're ready to go!


Configuration of sprite is done via config/sprite.yml. It allows you to set sprite configuration options, and fine tune exactly which sprites get generated where.

  • config: section defines all the global properties for sprite generation. Such as how it generates the styles, where it looks for images, where it writes it output file to, and what image file format it uses by default

    • style: defines how the style rules are outputted. built in options are css, sass, and sass_mixin. (defaults to css)
    • style_output_path: defines the file path where your style settings get written (defaults to stylesheets/sprites). the file extension not needed as it will be set based on the style: setting
    • image_output_path: defines the folder path where the combined sprite images files are written (defaults to images/sprites/)
    • image_source_path: defines the folder where source image files are read from (defaults to images/)
    • public_path: defines the root folder where static assets live (defaults to public/)
    • sprites_class: defines the class name that gets added to all sprite stylesheet rules (defaults to sprites)
    • default_format: defines the default file image format of the generated files. (defaults to png)
    • default_spacing: defines the default pixel spacing between sprites (defaults to 0)
    • class_separator: used to generated the class name by separating the image name and sprite name (defaults to -)
    • add_datestamps: whether or not to add datestamps to the generated background image urls. this will allow proper cache versioning (defaults to true)
  • images: section provides an array of configurations which define which image files are built, and where they get their sprites from. each image setup provides the following config options:

    • name: name of image (required)
    • sources: defines a list of source image filenames to build the target image from (required). They are parsed by Dir.glob
    • align: defines the composite gravity type, horizontal or vertical. (defaults to vertical)
    • spaced_by: spacing (in pixels) between the combined images. (defaults to 0)
    • format: define what image file format gets created (optional, uses default_format setting if not set)

All image and style paths should be set relative to the public folder (which is configurable via public_path setting).

Sample Configuration config/sprite.yml

# defines the base configuration options (file paths, etc, default style, etc)

  style: css
  style_output_path: stylesheets/sprites
  image_output_path: images/sprites/
  image_source_path: images/
  public_path: public/
  sprites_class: 'sprites'
  class_separator: '-'
  default_format: png
  default_spacing: 50

# defines what sprite collections get created

  # creates a public/images/sprites/blue_stars.png image with 4 sprites in it
  - name: blue_stars
    format: png
    align: horizontal
    spaced_by: 50
      - icons/blue-stars/small.png
      - icons/blue-stars/medium.png
      - icons/blue-stars/large.png
      - icons/blue-stars/xlarge.png
  # creates a public/images/sprites/green-stars.jpg image with 
  # all the gif files contained within /images/icons/green-stars/
  - name: green_stars
    format: png
    align: vertical
    spaced_by: 50
      - icons/green-stars/*.gif

Style Settings

By default, it will use with style: css and generate the file at public/stylesheets/sprites.css {
  background: url('/images/icons/blue-stars/small.png') no-repeat 0px 0px;
  width: 12px;
  height: 6px;
} {
  background: url('/images/icons/blue-stars/medium.png') no-repeat 0px 6px;
  width: 30px;
  height: 15px;
} {
  background: url('/images/icons/blue-stars/large.png') no-repeat 0px 21px;
  width: 60px;
  height: 30px;
} {
  background: url('/images/icons/blue-stars/xlarge.png') no-repeat 0px 96px;
  width: 100px;
  height: 75px;

We also support mixin syntax via style: sass_mixin. If set, it will generate a SASS mixin which you can use in order to mix in these sprites anywhere within your SASS stylesheets. For this option, set style_output_path: to stylesheets/sass/_sprites in order to generate the sass mixin file at stylesheets/sass/_sprites.sass

@import "sass/mixins/sprites.sass"

// you can then use your sprite like this
  +sprite("blue-stars", "large")

  +sprite("blue-stars", "small")

Additional style generators are very easy to add. We have one for style: sass and style: sass_ext. The sass_ext style is a work in progress, as it's attempting to write the sprite data to yml and use a dynamic sass extension to provide the mixin. Eventually, if it works, this will be the default for sass_mixin

Framework Integration??

sprite is provided as a command line helper. Deep web framework integration is not implemented at this time, however it shouldn't be needed. Just generate your sprites on your dev machine by running the command line, check in the resulting sprite images and stylesheets to your source control, and deploy!

You can also easily script it out via capistrano. You could also run sprite on application start, or just about anywhere. Let me know what limitations you run into.

ABOUT sprite

sprite was originally based off of Richard Huang's excellent Rails plugin: css_sprite

Since then it's been rebuilt (with some reuse of the image generation code) to be a general purpose ruby executable, with hooks for merb/rails/sinatra


Released under the MIT License


Copyright (c) 2009 Gist

Original Codebase Copyright (c) 2009 [Richard Huang]