SASS + Compass retina sprite mixin

get-sprite-retina

@mixin get-sprite($imgs, $name, $resize : false)
{
  $dimensions: true !default;
  $clean-up: true !default;
  $layout:vertical !default;

  $map: sprite-map($imgs, $layout: $layout, $cleanup: $clean-up, $spacing: 15px);
  background: $map no-repeat;

  @include sprite($map, $name, $dimensions, 0, 0);
  width: image-width(sprite-file($map, $name));
  height: image-height(sprite-file($map, $name));

  @if $resize
  {
    $ypos: round(nth(sprite-position($map, $name), 2) / 2);
    background-position: 0 $ypos;
    width: ceil(image-width(sprite-file($map, $name)) / 2);
    height: ceil(image-height(sprite-file($map, $name)) / 2);
    $sprites-width: ceil(image-width(sprite-path($map)) / 2);
    $sprites-height: ceil(image-height(sprite-path($map)) / 2);
    background-size: $sprites-width $sprites-height;
  }
}