# File lib/cairo/color.rb, line 57 def initialize(a) assert_in_range(a, "alpha channel") @alpha = a end
# File lib/cairo/color.rb, line 63 def assert_in_range(value, description) unless (0.0..1.0).include?(value) raise ArgumentError, "#{description} value should be in [0.0, 1.0]: #{value.inspect}" end end