def perform
unless options[:grid_dimensions] =~ /^(\d+)\+(\d+)(?:x(\d+))?$/
puts "ERROR: '#{options[:grid_dimensions]}' is not valid."
puts "Dimensions should be specified like: 30+10x20"
puts "where 30 is the column width, 10 is the gutter width, and 20 is the (optional) height."
return
end
logger.yellow do
$stderr.puts "Unless you need to check layouts in legacy browsers, it's preferable"
$stderr.puts "to use the pure CSS3-based grid background mixin:"
$stderr.puts
$stderr.puts "http://compass-style.org/reference/compass/layout/grid_background/"
end
column_width = $1.to_i
gutter_width = $2.to_i
height = $3.to_i if $3
filename = options[:grid_filename] || projectize("#{project_images_subdirectory}/grid.png")
GridBuilder.new(options.merge(:column_width => column_width, :gutter_width => gutter_width, :height => height, :filename => filename, :working_path => self.working_path)).generate!
end