168 lines
7.1 KiB
Markdown
168 lines
7.1 KiB
Markdown
---
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title: Spriting with Compass
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layout: tutorial
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crumb: Spriting
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classnames:
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- tutorial
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---
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# Spriting with Compass
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Spriting has never been easier with Compass. You place the sprite images to be in a folder,
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import them into your stylesheet, and then you can use the sprite in your selectors in one
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of several convenient ways.
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## Setup
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For this tutorial, let's imagine that in your project's image folder there are four icons:
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* `public/images/icon/new.png`
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* `public/images/icon/edit.png`
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* `public/images/icon/save.png`
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* `public/images/icon/delete.png`
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Each is an icon that is 32px square.
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## Basic Usage
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The simplest way to use these icon sprites is to let compass give you a class for each sprite:
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@import "icon/*.png";
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@include all-icon-sprites;
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And you'll get the following CSS output:
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.icon-sprite,
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.icon-delete,
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.icon-edit,
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.icon-new,
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.icon-save { background: url('/images/icon-34fe0604ab.png') no-repeat; }
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.icon-delete { background-position: 0 0; }
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.icon-edit { background-position: 0 -32px; }
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.icon-new { background-position: 0 -64px; }
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.icon-save { background-position: 0 -96px; }
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You can now apply the `icon-XXX` classes to your markup as needed.
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Let's go over what happened there. The import statement told compass to [generate a
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stylesheet that is customized for your sprites](https://gist.github.com/729507). This
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stylesheet is [magic](#magic-imports), it is not written to disk, and it can be customized
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by setting configuration variables before you import it. See the section below on
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[Customization Options](#customization-options). The goal of this stylesheet is to provide a
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simple naming convention for your sprites so that you they are easy to remember and use. You
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should never have to care what the is name of the generated sprite map, nor where a sprite
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is located within it.
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## Selector Control
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If you want control over what selectors are generated, it is easy to do. In this example,
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this is done by using the magic `icon-sprite` mixin. Note that the mixin's name is dependent
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on the name of the folder in which you've placed your icons.
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@import "icon/*.png";
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.actions {
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.new { @include icon-sprite(new); }
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.edit { @include icon-sprite(edit); }
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.save { @include icon-sprite(save); }
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.delete { @include icon-sprite(delete); }
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}
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And your stylesheet will compile to:
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.icon-sprite,
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.actions .new,
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.actions .edit,
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.actions .save,
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.actions .delete { background: url('/images/icon-34fe0604ab.png') no-repeat; }
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.actions .new { background-position: 0 -64px; }
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.actions .edit { background-position: 0 -32px; }
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.actions .save { background-position: 0 -96px; }
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.actions .delete { background-position: 0 0; }
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<a name="magic-imports"></a>
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## Magic Imports
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As noted above, compass will magically create sprite stylesheets for you. Some people like
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magic, some people are scared by it, and others are curious about how the magic works. If
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you would like to avoid the magic, you can use compass to generate an import for you. On the
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command line:
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compass sprite "public/images/icon/*.png"
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This will create file using your project's preferred syntax, or you can specify the
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output filename using the `-f` option and the syntax will be inferred from the extension.
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If you do this, you'll need to remember to regenerate the import whenever you rename, add,
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or remove sprites.
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Using the magic imports is recommended for most situations. But there are times when you
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might want to avoid it. For instance, if your sprite map has more than about 20 to 30
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sprites, you may find that hand crafting the import will speed up compilation times. See
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the section on [performance considerations](#performance) for more details.
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<a name="customization-options"></a>
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## Customization Options
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### Options per Sprite Map
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When constructing the sprite map, the entire sprite map and it's associated stylesheet
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can be configured in the following ways. Each option is specified by setting a [configuration
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variable](/help/tutorials/configurable-variables/) before importing the sprite. The variables
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are named according to the name of the folder containing the sprites. In the examples below
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the sprites were contained within a folder called `icon`.
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* `$<map>-spacing` -- The amount of transparent space, in pixels, around each sprite.
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Defaults to `0px`. E.g. `$icon-spacing: 20px`.
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* `$<map>-repeat` -- Wether or not each sprite should repeat along the x axis. Defaults
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to `no-repeat`. E.g. `$icon-repeat: repeat-x`.
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* `$<map>-position` -- The position of the sprite in the sprite map along the x-axis. Can
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be specified in pixels or percentage of the sprite map's width. `100%` would cause the
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sprite to be on the right-hand side of the sprite map. Defaults to `0px`.
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E.g. `$icon-position: 100%`.
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* `$<map>-sprite-dimensions` -- Whether or not the dimensions of the sprite should be
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included in each sprite's CSS output. Can be `true` or `false`. Defaults to `false`.
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* `$<map>-sprite-base-class` -- The base class for these sprites. Defaults to `.<map>-sprite`.
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E.g. `$icon-sprite-base-class: ".action-icon"`
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### Options per Sprite
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When constructing the sprite map, each sprite can be configured in the following ways:
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* `$<map>-<sprite>-spacing` -- The amount of transparent space, in pixels, around the sprite. Defaults
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to the sprite map's spacing which defaults to `0px`. E.g. `$icon-new-spacing: 20px`.
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* `$<map>-<sprite>-repeat` -- Wether or not the sprite should repeat along the x axis. Defaults
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to the sprite map's repeat which defaults to `no-repeat`. E.g. `$icon-new-repeat: repeat-x`.
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* `$<map>-<sprite>-position` -- The position of the sprite in the sprite map along the x-axis. Can
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be specified in pixels or percentage of the sprite map's width. `100%` would cause the
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sprite to be on the right-hand side of the sprite map. Defaults to the sprite map's
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position value which defaults to `0px`. E.g. `$icon-new-position: 100%`.
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<a name="performance"></a>
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## Performance Considerations
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Reading PNG files and assembling new images and saving them to disk might have a non-trivial
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impact to your stylesheet compilation times. Especially for the first compile. Please keep
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this in mind.
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## Large numbers of sprites
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The magic stylesheet can get very large when there are large numbers of sprites. 50 sprites
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will cause there to be over 150 variables created and then passed into the
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`sprite-map` [function](/reference/compass/helpers/sprites/#sprite-map).
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You may find that customizing the sprite function call to only pass those values that you
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are overriding will provide a small performance boost.
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See a [concrete example](https://gist.github.com/747970).
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## Oily PNG
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Compass generates PNG files using a pure-ruby library called
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[`chunky_png`](https://github.com/wvanbergen/chunky_png). This library can be made faster by
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installing a simple C extension called [`oily_png`](https://github.com/wvanbergen/oily_png).
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Add it to your `Gemfile` if you have one in your project:
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gem 'oily_png'
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Or install the Rubygem:
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gem install oily_png
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Compass will automatically detect its presence. |