compass/doc-src/content/help/tutorials/spriting.markdown

title	layout	crumb	classnames
Spriting with Compass	tutorial	Spriting	tutorial

Spriting with Compass

Spriting has never been easier with Compass. You place the sprite images to be in a folder, import them into your stylesheet, and then you can use the sprite in your selectors in one of several convenient ways.

Setup

For this tutorial, let's imagine that in your project's image folder there are four icons:

• public/images/icon/new.png
• public/images/icon/edit.png
• public/images/icon/save.png
• public/images/icon/delete.png

Each is an icon that is 32px square.

Basic Usage

The simplest way to use these icon sprites is to let compass give you a class for each sprite:

@import "icon/*.png";
@include all-icon-sprites;

And you'll get the following CSS output:

.icon-sprite,
.icon-delete,
.icon-edit,
.icon-new,
.icon-save   { background: url('/images/icon-34fe0604ab.png') no-repeat; }

.icon-delete { background-position: 0 0; }
.icon-edit   { background-position: 0 -32px; }
.icon-new    { background-position: 0 -64px; }
.icon-save   { background-position: 0 -96px; }

You can now apply the icon-XXX classes to your markup as needed.

Let's go over what happened there. The import statement told compass to generate a stylesheet that is customized for your sprites. This stylesheet is magic, it is not written to disk, and it can be customized by setting configuration variables before you import it. See the section below on Customization Options. The goal of this stylesheet is to provide a simple naming convention for your sprites so that you they are easy to remember and use. You should never have to care what the is name of the generated sprite map, nor where a sprite is located within it.

Selector Control

If you want control over what selectors are generated, it is easy to do. In this example, this is done by using the magic icon-sprite mixin. Note that the mixin's name is dependent on the name of the folder in which you've placed your icons.

@import "icon/*.png";

.actions {
  .new    { @include icon-sprite(new);    }
  .edit   { @include icon-sprite(edit);   }
  .save   { @include icon-sprite(save);   }
  .delete { @include icon-sprite(delete); }
}

And your stylesheet will compile to:

.icon-sprite,
.actions .new,
.actions .edit,
.actions .save,
.actions .delete { background: url('/images/icon-34fe0604ab.png') no-repeat; }

.actions .new    { background-position: 0 -64px; }
.actions .edit   { background-position: 0 -32px; }
.actions .save   { background-position: 0 -96px; }
.actions .delete { background-position: 0 0;     }

Magic Imports

As noted above, compass will magically create sprite stylesheets for you. Some people like magic, some people are scared by it, and others are curious about how the magic works. If you would like to avoid the magic, you can use compass to generate an import for you. On the command line:

compass sprite "public/images/icon/*.png"

This will create file using your project's preferred syntax, or you can specify the output filename using the -f option and the syntax will be inferred from the extension. If you do this, you'll need to remember to regenerate the import whenever you rename, add, or remove sprites.

Using the magic imports is recommended for most situations. But there are times when you might want to avoid it. For instance, if your sprite map has more than about 20 to 30 sprites, you may find that hand crafting the import will speed up compilation times. See the section on performance considerations for more details.

Customization Options

Options per Sprite Map

When constructing the sprite map, the entire sprite map and it's associated stylesheet can be configured in the following ways. Each option is specified by setting a configuration variable before importing the sprite. The variables are named according to the name of the folder containing the sprites. In the examples below the sprites were contained within a folder called icon.

• $<map>-spacing -- The amount of transparent space, in pixels, around each sprite. Defaults to 0px. E.g. $icon-spacing: 20px.
• $<map>-repeat -- Wether or not each sprite should repeat along the x axis. Defaults to no-repeat. E.g. $icon-repeat: repeat-x.
• $<map>-position -- The position of the sprite in the sprite map along the x-axis. Can be specified in pixels or percentage of the sprite map's width. 100% would cause the sprite to be on the right-hand side of the sprite map. Defaults to 0px. E.g. $icon-position: 100%.
• $<map>-sprite-dimensions -- Whether or not the dimensions of the sprite should be included in each sprite's CSS output. Can be true or false. Defaults to false.
• $<map>-sprite-base-class -- The base class for these sprites. Defaults to .<map>-sprite. E.g. $icon-sprite-base-class: ".action-icon"

Options per Sprite

When constructing the sprite map, each sprite can be configured in the following ways:

• $<map>-<sprite>-spacing -- The amount of transparent space, in pixels, around the sprite. Defaults to the sprite map's spacing which defaults to 0px. E.g. $icon-new-spacing: 20px.
• $<map>-<sprite>-repeat -- Wether or not the sprite should repeat along the x axis. Defaults to the sprite map's repeat which defaults to no-repeat. E.g. $icon-new-repeat: repeat-x.
• $<map>-<sprite>-position -- The position of the sprite in the sprite map along the x-axis. Can be specified in pixels or percentage of the sprite map's width. 100% would cause the sprite to be on the right-hand side of the sprite map. Defaults to the sprite map's position value which defaults to 0px. E.g. $icon-new-position: 100%.

Performance Considerations

Reading PNG files and assembling new images and saving them to disk might have a non-trivial impact to your stylesheet compilation times. Especially for the first compile. Please keep this in mind.

Large numbers of sprites

The magic stylesheet can get very large when there are large numbers of sprites. 50 sprites will cause there to be over 150 variables created and then passed into the sprite function. You may find that customizing the sprite function call to only pass those values that you are overriding will provide a performance boost.

Oily PNG

Compass generates PNG files using a pure-ruby library called chunky_png. This library can be made faster by installing a simple C extension called oily_png. Add it to your Gemfile if you have one in your project:

gem 'oily_png'

Or install the Rubygem:

gem install oily_png

Compass will automatically detect its presence.