rgbapng - Compass plugin

rgbapng is a Compass plugin for providing cross browser compatible RGBA support. It works by creating single pixel transparent PNGs on the fly for browsers that don't support RGBA. It uses the pure Ruby ChunkyPNG library resulting in hassle-free installation and deployment, and increased performance.

Installation

Installation is simple via Ruby Gems. Compass and ChunkyPNG are required.

gem install compass-rgbapng

Using rgbapng with your Compass project

To use rgbapng with your project, require the plugin from your Compass configuration:

require "rgbapng"

And then import the mixins to your SASS/SCSS files:

@import "rgbapng";

Configurable variables

There is a single variable that defines the path to which your PNG images will be saved. This defaults to rgbapng inside your Compass images directory. Change the path globally with:

$rgbapng_path: 'my_pngs';

Mixins

There are two mixins available to you.

rgba-background($color, [$path])

Sets the background property to use the RGBA value, falling back to the compiled PNG.

@include rgba-background(rgba(0,0,0,0.75));

Compiles to:

background: url('/images/rgbapng/000000bf.png?1282127952');
background: rgba(0, 0, 0, 0.75);

rgba-background-inline($color)

Sets the background property to use the RGBA value, falling back to a base64 encoded image data.

@include rgba-background-inline(rgba(0,0,0,0.75));

Compiles to:

background: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR4nGNh2A8AAM4AxOSyusMAAAAASUVORK5CYII=');
background: rgba(0, 0, 0, 0.75);

Functions

There are two Sass::Script functions which can be used in your SASS:

# Creates the single pixel PNG image
# Returns a String of the image path and filename
png_pixelate(color, [dir])

# Returns a String of the base64 encoded image data
png_base64(color)

Credit where it's due

• The CSS technique used was initially described by Lea Verou in Bulletproof, cross-browser RGBA backgrounds, today.
• The SASS functions were first created by Benjamin Doherty using the RMagick library.

Copyright

Copyright (c) 2010 Aaron Russell. See LICENSE for details.