CssSprites - A Rails plugin for generate CSS sprites

This plugin helps to generate CSS sprites with the images of the public/images/ directory.

Installation

$ script/plugin install git://github.com/setepo/css-sprites

The installer will copy blank.gif in public/images, and a configuration file in config/. Before copy the files it checks if there is any file with the same name, and will not override existing files.

Usage

You don’t need to change your code.

The first step is generate the index:

$ rake css_sprites:update

This will find all the images and make a bundle with them. Animated images (like GIF or APNG with two or more frames) are always excluded.

The plugin will create one image per format (a file with JPEG images, another file with PNGs, …).

And that is all.

When you use image_tag in your views, the plugin will check if the requested image is available in the index, and, if it is found, generate something like this:

<img alt="Some text" height="16" src="/images/blank.gif?12345678" style="background: url(/images/css-sprites-image-bundle.png?12345678) -0px -466px; " width="16" />

This HTML is generated with the original image_tag, so all the Rails features (like assets, timestamp suffix, URL prefix) are available.

If you don’t want to use sprites, just remove the generated bundles.

The plugin doesn’t check the timestamps, so you have to call rake css_sprites:update again when you modify the images of the index, or you want to add new images. The bundles are generated from scratch, so if you remove images, they will disappear from the bundles after rake css_sprites:update

Example configuration

The initial configuration is this:

max-width: 100
max-height: 100
background: blank.gif
file-bundle: css-sprites-image-bundle
max-files-per-bundle: 75
files:
    - **/*.png
    - **/*.gif
    - **/*.jpeg
    - **/*.jpg

The most interesting key is files: with it, you can specify what files do you want to add to the index. By default it includes all the most common files, recursively. Take a look to Dir.glob documentation if you want to know the details of the patterns.

Dependencies

RMagick

TODO

Tests