Class: MirrorMirror::Transformation::BackgroundPosition

Inherits:
PropertyTransformation show all
Defined in:
lib/mirror-mirror/transformation/background_position.rb

Constant Summary collapse

ONE_HUNDRED_PERCENT = 
Sass::Script::Number.new(100, ["%"], [])
POSITION_KEYWORDS = 
Set.new(%w(top bottom left right center))

Instance Method Summary collapse

Methods inherited from PropertyTransformation

instances, #transform_name, #transform_name?, #transform_value, #transform_value?

Methods inherited from Base

inherited, instances

Instance Method Details

#flip_it(e, position) ⇒ Object 



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# File 'lib/mirror-mirror/transformation/background_position.rb', line 71

def flip_it(e, position)
  return e unless e.respond_to?(:value)
  case e
  when Sass::Script::Number
    if position == 0 && e.value == 0
      opts(e.options) { ONE_HUNDRED_PERCENT.dup }
    elsif position == 0 && e.numerator_units.first == "%"
      opts(e.options) { ONE_HUNDRED_PERCENT.minus(e) }
    elsif position == 0
      Sass.logger.warn("Line #{e.line}: Cannot flip background position: #{e}")
      e
    else
      e
    end
  when Sass::Script::String
    case e.value
    when "right"
      e.value.replace("left")
    when "left"
      e.value.replace("right")
    end
    e
  else
    e
  end
end

#legal_as_background_position?(e) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/mirror-mirror/transformation/background_position.rb', line 100

def legal_as_background_position?(e)
  case e
  when Sass::Script::String
    POSITION_KEYWORDS.include?(e.value)
  when Sass::Script::Number
    true
  else
    false
  end
end

#transform_background(expression) ⇒ Object 



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# File 'lib/mirror-mirror/transformation/background_position.rb', line 17

def transform_background(expression)
  unless expression.is_a?(Sass::Script::List)
    expression = opts(expression.options) do
      Sass::Script::List.new([expression], :space)
    end
  end
  positions = []
  position_indices = []
  expression.value.each_with_index do |v, i|
    if legal_as_background_position?(v)
      positions << v
      position_indices << i
    else
      break if positions.any?
      next
    end
    positions
  end
  return expression unless positions.any?
  if positions.size > 2
    Sass.logger.warn("Line #{expression.line}: malformed background: #{expression.to_sass}")
    return expression
  end
  # tranform the background position elements and replace the position
  # section of the shorthand with it
  transformed = transform_background_position(Sass::Script::List.new(positions, :space))
  position_indices << position_indices.first if position_indices.size < 2
  expression.value[Range.new(*position_indices)] = transformed.value
  expression
end

#transform_background_position(expression) ⇒ Object 



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# File 'lib/mirror-mirror/transformation/background_position.rb', line 48

def transform_background_position(expression)
  unless expression.is_a?(Sass::Script::List)
    expression = opts(expression.options) do
      Sass::Script::List.new([expression], :space)
    end
  end
  if expression.value.size > 2
    # positions with offsets
    expression.value.each_with_index do |e, i|
      next if i % 2 == 1
      expression.value[i] = flip_it(e, i / 2)
    end
  else
    # positions
    expression.value.each_with_index do |e, i|
      expression.value[i] = flip_it(e, i)
    end
  end
  expression
end

#transform_expression(name, expression) ⇒ Object 



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# File 'lib/mirror-mirror/transformation/background_position.rb', line 7

def transform_expression(name, expression)
  for_each_value(expression) do |e|
    if name == "background"
      transform_background(e)
    else
      transform_background_position(e)
    end
  end
end

#transform_expression?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/mirror-mirror/transformation/background_position.rb', line 3

def transform_expression?(name)
  name == "background" || name == "background-position" || name == "background-position-x"
end