chriseppstein/compass

// Determines those states for which you want to enable magic sprite selectors
$sprite-selectors: hover, target, active, focus !default;

// Set the width and height of an element to the original
// dimensions of an image before it was included in the sprite.
@mixin sprite-dimensions($map, $sprite) {
  height: image-height(sprite-file($map, $sprite));
  width: image-width(sprite-file($map, $sprite));
}

// Set the background position of the given sprite `$map` to display the
// sprite of the given `$sprite` name. You can move the image relative to its
// natural position by passing `$offset-x` and `$offset-y`.
// The background-position will be returned in pixels. By passing `true
// for `$use_percentages`, you get percentages instead.
@mixin sprite-background-position($map, $sprite, $offset-x: 0, $offset-y: 0,
$use-percentages: false) {
  background-position: sprite-position($map, $sprite, $offset-x, $offset-y,
  $use-percentages);
}


// Determines if you want to include magic selectors in your sprites
$disable-magic-sprite-selectors: false !default;

// Set this to underscore if you prefer
$default-sprite-separator: "-" !default;

// Include the position and (optionally) dimensions of this `$sprite`
// in the given sprite `$map`. The sprite url should come from either a base
// class or you can specify the `sprite-url` explicitly like this:
//
//     background: $map no-repeat;
@mixin sprite($map, $sprite, $dimensions: false, $offset-x: 0, $offset-y: 0,
                             $use-percentages: false,
                             $use-magic-selectors: not $disable-magic-sprite-selectors,
                             $separator: $default-sprite-separator) {
  @include sprite-background-position($map, $sprite, $offset-x, $offset-y,
                                      $use-percentages);
  @if $dimensions {
    @include sprite-dimensions($map, $sprite);
  }
  @if $use-magic-selectors {
    @include sprite-selectors($map, $sprite, $sprite, $offset-x, $offset-y,
                              $use-percentages, $separator);
  }
}

// Include the selectors for the `$sprite` given the `$map` and the 
// `$full-sprite-name`
// @private
@mixin sprite-selectors($map, $sprite-name, $full-sprite-name, $offset-x: 0,
                        $offset-y: 0, $use-percentages: false,
                        $separator: $default-sprite-separator) {
  @each $state in $sprite-selectors {
    $sprite-class: "#{$full-sprite-name}#{$separator}#{$state}";
    @if sprite_has_selector($map, $sprite-name, $state) {
      @if sprite_has_valid_selector($sprite-class) {
        &:#{$state}, &.#{$sprite-class} {
            @include sprite-background-position($map, sprite_selector_file($map, $sprite-name, $state),
                                                $offset-x, $offset-y, $use-percentages);
        }
      }
    }
  }
}

// Generates a class for each space separated name in `$sprite-names`.
// The class will be of the form .<map-name>-<sprite-name>.
//
// If a base class is provided, then each class will extend it.
//
// If `$dimensions` is `true`, the sprite dimensions will specified.
// Positions are returned in pixel units. Set `$use_percentages` to true to
// instead get percentages.
@mixin sprites($map, $sprite-names, $base-class: false, $dimensions: false,
               $prefix: sprite-map-name($map), $offset-x: 0, $offset-y: 0,
               $use-percentages: false,
               $separator: $default-sprite-separator) {
  @each $sprite-name in $sprite-names {
    @if sprite_does_not_have_parent($map, $sprite-name) {
      $full-sprite-name: "#{$prefix}#{$separator}#{$sprite-name}";
      @if sprite_has_valid_selector($full-sprite-name) {
        .#{$full-sprite-name} {
          @if $base-class { @extend #{$base-class}; }
          @include sprite($map, $sprite-name, $dimensions, $offset-x, $offset-y, 
                          $use-percentages, $separator: $separator);
        }
      }
    }
  }
}