def sprite_position(map, sprite = nil, offset_x = ZERO, offset_y = ZERO)
assert_type offset_x, :Number
assert_type offset_y, :Number
sprite = convert_sprite_name(sprite)
verify_map(map, "sprite-position")
unless sprite && sprite.is_a?(Sass::Script::String)
raise Sass::SyntaxError, %Q(The second argument to sprite-position must be a sprite name. See http://beta.compass-style.org/help/tutorials/spriting/ for more information.)
end
image = map.image_for(sprite.value)
unless image
missing_image!(map, sprite)
end
if offset_x.unit_str == "%"
x = offset_x
else
x = offset_x.value - image.left
x = Sass::Script::Number.new(x, x == 0 ? [] : ["px"])
end
y = offset_y.value - image.top
y = Sass::Script::Number.new(y, y == 0 ? [] : ["px"])
Sass::Script::List.new([x, y],:space)
end