Using Compass to generate normal and retina sprite maps

compass-retina-sprites.scss

$sprites: sprite-map("sprites/*.png");
$sprites-retina: sprite-map("sprites-retina/*.png");

@mixin sprite-background($name) {
  background-image: sprite-url($sprites);
  background-position: sprite-position($sprites, $name);
  background-repeat: no-repeat;
  display: block;
  height: image-height(sprite-file($sprites, $name));
  width: image-width(sprite-file($sprites, $name));
  @media (-webkit-min-device-pixel-ratio: 2), (-o-min-device-pixel-ratio: 3/2), (min-device-pixel-ratio: 2) {
    // Workaround for https://gist.github.com/2140082
    @if (sprite-position($sprites, $name) != sprite-position($sprites-retina, $name)) {
      $ypos: round(nth(sprite-position($sprites-retina, $name), 2) / 2);
      background-position: 0 $ypos;
    }
    // Hard coded width of the normal sprite image. There must be a smarter way to do this.
    @include background-size(444px auto);
    background-image: sprite-url($sprites-retina);
  }
}

// Usage.
.mail-icon {
  @include sprite-background(mail);
}

here is my take on retina sprites. i wanted a way to use it within the @media directive as well...

https://gist.github.com/brewster1134/13162e2cb0220e87b017

I would love some feedback...

Here is my try to make it little short and for best practice. I wanted to use background-image property for once instead of using it in every class to minimise my code. I make this
https://github.com/mbilalsiddique1/Sass-Mixins

@import "compass/utilities/sprites";         // Include compass sprite helpers
@import "compass/css3/background-size";      // Include helper to calc background size

// General Sprite Defaults
// You can override them before you import this file.
$icon-sprite-base-class: ".icon-sprite" !default;
$icon-sprite-dimensions: false !default;
$icon-spacing: 10px !default;
$icon-position: 0% !default;
$icon-repeat: no-repeat !default;

$icon-sprites: sprite-map("sprites/*.png", $spacing: $icon-spacing, $repeat: $icon-repeat, $position: $icon-position);
$icon-sprites-retina: sprite-map("sprites-retina/*.png", $spacing: $icon-spacing * 2, $repeat: $icon-repeat, $position: $icon-position);

// All sprites should extend this class
// The icon-sprite mixin will do so for you.
#{$icon-sprite-base-class} {
  background: $icon-sprites $icon-repeat;
}

@media (-webkit-min-device-pixel-ratio: 1.5), (min--moz-device-pixel-ratio: 1.5), (-o-min-device-pixel-ratio: 3 / 2), (min-device-pixel-ratio: 1.5), (min-resolution: 1.5dppx) {
  #{$icon-sprite-base-class} {
    background: $icon-sprites-retina $icon-repeat;
    @include background-size(ceil(image-width(sprite-path($icon-sprites-retina)) / 2) auto);
  }
}

// Extends the sprite base class and set the background position for the desired sprite.
// It will also apply the image dimensions if $dimensions is true.
@mixin icon-sprite($name, $dimensions: $icon-sprite-dimensions, $offset-x: 0, $offset-y: 0) {
  @extend #{$icon-sprite-base-class};
  @include sprite($icon-sprites, $name, $dimensions, $offset-x, $offset-y)
}

// Example Usage.
.icon-analytics {
    @include icon-sprite(main-sprite);
}

My smaller contribution: https://gist.github.com/tomasdev/56bc62e86ab0700f8298 works right out of the box if you're planning to save only the biggest assets and not the pixelated (non-retina) ones.

@mbilalsiddique1 - thanks for this bit above. Working well for my usage thus far. Maybe i missed it, but any way to have the css for all icons in the folder automatically render with their unique file names as classes, instead of defining each one again ( as you show in your example ) ?

// Example Usage. .icon-analytics { @include icon-sprite(main-sprite); }

I believe i figured it out how to declare all the sprites in the map. Works well on top of whats above.

$sprite-names: sprite_names($icon-sprites);
@each $sprite in $sprite-names {
    .icon-#{$sprite} {
      @include icon-sprite($sprite, true);
    }
} 

How to combine this mixin to get the image height of the sprite?