Class: R2::Swapper

Inherits:
Object
  • Object
show all
Defined in:
lib/r2.rb

Overview

Reuable class for CSS alterations

Constant Summary collapse

PROPERTY_MAP = 
{
  'margin-left' => 'margin-right',
  'margin-right' => 'margin-left',

  'padding-left' => 'padding-right',
  'padding-right' => 'padding-left',

  'border-left' => 'border-right',
  'border-right' => 'border-left',

  'border-left-width' => 'border-right-width',
  'border-right-width' => 'border-left-width',

  'border-radius-bottomleft' => 'border-radius-bottomright',
  'border-radius-bottomright' => 'border-radius-bottomleft',
  'border-radius-topleft' => 'border-radius-topright',
  'border-radius-topright' => 'border-radius-topleft',

  '-moz-border-radius-bottomright' => '-moz-border-radius-bottomleft',
  '-moz-border-radius-bottomleft' => '-moz-border-radius-bottomright',
  '-moz-border-radius-topright' => '-moz-border-radius-topleft',
  '-moz-border-radius-topleft' => '-moz-border-radius-topright',

  '-webkit-border-top-right-radius' => '-webkit-border-top-left-radius',
  '-webkit-border-top-left-radius' => '-webkit-border-top-right-radius',
  '-webkit-border-bottom-right-radius' => '-webkit-border-bottom-left-radius',
  '-webkit-border-bottom-left-radius' => '-webkit-border-bottom-right-radius',

  'left' => 'right',
  'right' => 'left'
}
VALUE_PROCS = 
{
  'padding'    => lambda {|obj,val| obj.quad_swap(val) },
  'margin'     => lambda {|obj,val| obj.quad_swap(val) },
  'border-radius' => lambda {|obj,val| obj.border_radius_swap(val) },
  '-moz-border-radius' => lambda {|obj,val| obj.border_radius_swap(val) },
  '-webkit-border-radius' => lambda {|obj,val| obj.border_radius_swap(val) },
  'text-align' => lambda {|obj,val| obj.side_swap(val) },
  'float'      => lambda {|obj,val| obj.side_swap(val) },
  'box-shadow' => lambda {|obj,val| obj.shadow_swap(val) },
  '-webkit-box-shadow' => lambda {|obj,val| obj.shadow_swap(val) },
  '-moz-box-shadow' => lambda {|obj,val| obj.shadow_swap(val) },
  'direction'  => lambda {|obj,val| obj.direction_swap(val) },
  'clear' => lambda {|obj,val| obj.side_swap(val) },
  'background-position' => lambda {|obj,val| obj.background_position_swap(val) }
}

Instance Method Summary collapse

Instance Method Details

#background_position_swap(val) ⇒ Object

Given a background-position such as left center or 0% 50% return the opposing value e.g right center or 100% 50%



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# File 'lib/r2.rb', line 200

def background_position_swap(val)

  if val =~ /left/
    val.gsub!('left', 'right')
  elsif val =~ /right/
    val.gsub!('right', 'left')
  end

  points = val.strip.split(/\s+/)

  # If first point is a percentage-value
  if match = points[0].match(/(\d+)%/)
    inv = 100 - match[1].to_i # 30% => 70% (100 - x)
    val = ["#{inv}%", points[1]].compact.join(' ')
  end

  # If first point is a unit-value
  if match = points[0].match(/^(\d+[a-z]{2,3})/)
    val = ["right", match[1], points[1] || "center"].compact.join(' ')
  end

  val
end

#border_radius_swap(val) ⇒ Object

Border radius uses top-left, top-right, bottom-left, bottom-right, so all values need to be swapped. Additionally, two and three value border-radius declarations need to be swapped as well. Vertical radius, specified with a /, should be left alone.



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# File 'lib/r2.rb', line 180

def border_radius_swap(val)
  # 1px 2px 3px 4px => 1px 4px 3px 2px
  points = val.to_s.split(/\s+/)

  if points && points.length > 1 && !val.to_s.include?('/')
    case points.length
    when 4
      [points[1], points[0], points[3], points[2]].join(' ')
    when 3
      [points[1], points[0], points[1], points[2]].join(' ')
    when 2
      [points[1], points[0]].join(' ')
    else val
    end
  else
    val
  end
end

#declaration_swap(decl) ⇒ Object

Given a single CSS declaration rule (e.g. padding-left: 4px) return the opposing rule (so, padding-right:4px; in this example)



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# File 'lib/r2.rb', line 119

def declaration_swap(decl)
  return '' unless decl

  matched = decl.match(/([^:]+):(.+)$/)
  return '' unless matched

  property = matched[1]
  value = matched[2]

  property = PROPERTY_MAP[property] if PROPERTY_MAP.has_key?(property)
  value = VALUE_PROCS[property].call(self, value) if VALUE_PROCS.has_key?(property)

  return property + ':' + value + ';'
end

#direction_swap(val) ⇒ Object

Given a value of rtl or ltr return the opposing value. All other arguments are ignored and returned unmolested.



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# File 'lib/r2.rb', line 135

def direction_swap(val)
  if val == "rtl"
    "ltr"
  elsif val == "ltr"
    "rtl"
  else
    val
  end
end

#minimize(css) ⇒ Object

Minimize the provided CSS by removing comments, and extra specs



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# File 'lib/r2.rb', line 108

def minimize(css)
  return '' unless css

  css.gsub(/\/\*[\s\S]+?\*\//, '').   # comments
     gsub(/[\n\r]/, '').              # line breaks and carriage returns
     gsub(/\s*([:;,\{\}])\s*/, '\1'). # space between selectors, declarations, properties and values
     gsub(/\s+/, ' ').                # replace multiple spaces with single spaces
     gsub(/(\A\s+|\s+\z)/, '')        # leading or trailing spaces
end

#quad_swap(val) ⇒ Object

Given a 4-argument CSS declaration value (like that of padding or margin) return the opposing value. The opposing value swaps the left and right but not the top or bottom. Any unrecognized argument is returned unmolested (for example, 2-argument values)



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# File 'lib/r2.rb', line 159

def quad_swap(val)
  # 1px 2px 3px 4px => 1px 4px 3px 2px
  points = val.to_s.split(/\s+/)

  if points && points.length == 4
    [points[0], points[3], points[2], points[1]].join(' ')
  else
    val
  end
end

#r2(original_css) ⇒ Object

Given a String of CSS perform the full directionality change



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# File 'lib/r2.rb', line 69

def r2(original_css)
  css = minimize(original_css)

  result = css.gsub(/([^\{\}]+[^\}]|[\}])+?/) do |rule|
    # +rule+ can represent a selector (".foo {"), the closing "}" for a selector, or the complete
    # body of a a selector
    if rule.match(/[\{\}]/)
      # it is a selector with "{" or a closing "}", insert as it is. This is
      # things like ".foo {" and its matching "}"
      rule_str = rule
    else
      # It is a declaration body, like "padding-left:4px;margin-left:5px;"
      rule_str = ""
      # Split up the individual rules in the body and process each swap. To handle the
      # possible ";" in the url() definitions, like
      # url("data;base64") and url("data:image/svg+xml;charset=...")
      # a state machine is constructed.
      url_rule = nil
      rule.split(/;/).each do |part|
        # A rule body that contains a "url(" and a ";" before the closing ")"
        if part.match(/url\([^\)]+$/)
          url_rule = part
        elsif url_rule != nil
          url_rule << ";" + part
          if part.match(/\)( |$)/)
            rule_str << declaration_swap(url_rule)
            url_rule = nil
          end
        else
          rule_str << declaration_swap(part)
        end
      end
    end
    rule_str
  end
  return result
end

#shadow_swap(val) ⇒ Object

Given the 2-6 variable declaration for box-shadow convert the direction. Conversion requires inverting the horizontal measure only.



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# File 'lib/r2.rb', line 172

def shadow_swap(val)
  ShadowFlipper::flip(val)
end

#side_swap(val) ⇒ Object

Given a value of right or left return the opposing value. All other arguments are ignored and returned unmolested.



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# File 'lib/r2.rb', line 146

def side_swap(val)
  if val == "right"
    "left"
  elsif val == "left"
    "right"
  else
    val
  end
end