Class: SvgConform::CssColor

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

Overview

Handles CSS color equivalence, normalization, and conversion

Constant Summary collapse

NAMED_COLORS =

Named colors mapping to their hex equivalents

{
  "black" => "#000000",
  "white" => "#ffffff",
  "red" => "#ff0000",
  "green" => "#008000",
  "blue" => "#0000ff",
  "yellow" => "#ffff00",
  "cyan" => "#00ffff",
  "magenta" => "#ff00ff",
  "silver" => "#c0c0c0",
  "gray" => "#808080",
  "grey" => "#808080",
  "maroon" => "#800000",
  "olive" => "#808000",
  "lime" => "#00ff00",
  "aqua" => "#00ffff",
  "teal" => "#008080",
  "navy" => "#000080",
  "fuchsia" => "#ff00ff",
  "purple" => "#800080",
}.freeze
HEX_TO_NAMED =

Reverse mapping for canonical named color lookup

NAMED_COLORS.invert.freeze
SPECIAL_KEYWORDS =

CSS color keywords that have special meaning

%w[inherit currentcolor transparent none].freeze

Class Method Summary collapse

Class Method Details

.allowed_in_list?(color, allowed_colors) ⇒ Boolean

Check if a color is in a list of allowed colors (with equivalence)

Returns:

  • (Boolean) 


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# File 'lib/svg_conform/css_color.rb', line 179

def allowed_in_list?(color, allowed_colors)
  return false if color.nil? || allowed_colors.nil? || allowed_colors.empty?

  normalized = normalize(color)
  return false if normalized.nil?

  allowed_colors.any? { |allowed| equivalent?(color, allowed) }
end

.equivalent?(color1, color2) ⇒ Boolean

Check if two colors are equivalent

Returns:

  • (Boolean) 


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# File 'lib/svg_conform/css_color.rb', line 94

def equivalent?(color1, color2)
  return false if color1.nil? || color2.nil?
  return true if color1 == color2

  norm1 = normalize(color1)
  norm2 = normalize(color2)

  return false if norm1.nil? || norm2.nil?

  norm1 == norm2
end

.equivalent_forms(color) ⇒ Object

Get all equivalent forms of a color



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# File 'lib/svg_conform/css_color.rb', line 154

def equivalent_forms(color)
  normalized = normalize(color)
  return [color] if normalized.nil?

  forms = [normalized]

  # Add named form if available
  named = HEX_TO_NAMED[normalized]
  forms << named if named

  # Add short hex form if applicable
  if normalized.match?(/^#([0-9a-f])\1([0-9a-f])\2([0-9a-f])\3$/)
    short_hex = "##{$1}#{$2}#{$3}"
    forms << short_hex
  end

  # Add uppercase variants for hex
  if normalized.match?(/^#[0-9a-f]{6}$/)
    forms << normalized.upcase
  end

  forms.uniq
end

.expand_short_hex(hex) ⇒ Object

Expand short hex colors: #fff → #ffffff



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# File 'lib/svg_conform/css_color.rb', line 123

def expand_short_hex(hex)
  return hex unless hex.match?(/^#[0-9a-f]{3}$/)

  chars = hex[1..3].chars
  "##{chars.map { |c| c * 2 }.join}"
end

.normalize(color) ⇒ Object

Normalize a color to its canonical hex representation



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# File 'lib/svg_conform/css_color.rb', line 37

def normalize(color)
  return nil if color.nil? || color.empty?

  color = color.strip.downcase

  # Handle special keywords
  return color if SPECIAL_KEYWORDS.include?(color)

  # Handle named colors
  return NAMED_COLORS[color] if NAMED_COLORS.key?(color)

  # Handle hex colors
  if color.match?(/^#[0-9a-f]{3}$/)
    # Expand short hex: #fff → #ffffff
    return expand_short_hex(color)
  elsif color.match?(/^#[0-9a-f]{6}$/)
    # Already normalized 6-digit hex
    return color
  end

  # Handle RGB functions with integers
  rgb_match = color.match(/^rgb\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)$/)
  if rgb_match
    r, g, b = rgb_match[1..3].map(&:to_i)
    return rgb_to_hex(r, g, b)
  end

  # Handle RGB functions with percentages
  rgb_percent_match = color.match(/^rgb\s*\(\s*(\d+(?:\.\d+)?)%\s*,\s*(\d+(?:\.\d+)?)%\s*,\s*(\d+(?:\.\d+)?)%\s*\)$/)
  if rgb_percent_match
    r = (rgb_percent_match[1].to_f * 255 / 100).round
    g = (rgb_percent_match[2].to_f * 255 / 100).round
    b = (rgb_percent_match[3].to_f * 255 / 100).round
    return rgb_to_hex(r, g, b)
  end

  # Handle mixed RGB functions (percentage and absolute values)
  rgb_mixed_match = color.match(/^rgb\s*\(\s*(\d+(?:\.\d+)?%?)\s*,\s*(\d+(?:\.\d+)?%?)\s*,\s*(\d+(?:\.\d+)?%?)\s*\)$/)
  if rgb_mixed_match
    r = parse_rgb_value(rgb_mixed_match[1])
    g = parse_rgb_value(rgb_mixed_match[2])
    b = parse_rgb_value(rgb_mixed_match[3])
    return rgb_to_hex(r, g, b)
  end

  # Handle RGBA functions (ignore alpha for SVG purposes)
  rgba_match = color.match(/^rgba\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*,\s*[\d.]+\s*\)$/)
  if rgba_match
    r, g, b = rgba_match[1..3].map(&:to_i)
    return rgb_to_hex(r, g, b)
  end

  # Return original if unrecognized format
  color
end

.rgb_sum(color) ⇒ Object

Calculate RGB sum for threshold-based validation



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# File 'lib/svg_conform/css_color.rb', line 189

def rgb_sum(color)
  return nil if color.nil? || color.empty?

  color = color.strip.downcase

  # Handle hex colors
  if color.match?(/^#[0-9a-f]{3}$/)
    # Expand short hex and calculate
    expanded = expand_short_hex(color)
    r = expanded[1..2].to_i(16)
    g = expanded[3..4].to_i(16)
    b = expanded[5..6].to_i(16)
    return r + g + b
  elsif color.match?(/^#[0-9a-f]{6}$/)
    r = color[1..2].to_i(16)
    g = color[3..4].to_i(16)
    b = color[5..6].to_i(16)
    return r + g + b
  end

  # Handle RGB functions with integers
  rgb_match = color.match(/^rgb\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)$/)
  if rgb_match
    r, g, b = rgb_match[1..3].map(&:to_i)
    return r + g + b
  end

  # Handle RGB functions with percentages
  rgb_percent_match = color.match(/^rgb\s*\(\s*(\d+(?:\.\d+)?)%\s*,\s*(\d+(?:\.\d+)?)%\s*,\s*(\d+(?:\.\d+)?)%\s*\)$/)
  if rgb_percent_match
    r = (rgb_percent_match[1].to_f * 255 / 100).round
    g = (rgb_percent_match[2].to_f * 255 / 100).round
    b = (rgb_percent_match[3].to_f * 255 / 100).round
    return r + g + b
  end

  # Handle mixed RGB functions
  rgb_mixed_match = color.match(/^rgb\s*\(\s*(\d+(?:\.\d+)?%?)\s*,\s*(\d+(?:\.\d+)?%?)\s*,\s*(\d+(?:\.\d+)?%?)\s*\)$/)
  if rgb_mixed_match
    r = parse_rgb_value(rgb_mixed_match[1])
    g = parse_rgb_value(rgb_mixed_match[2])
    b = parse_rgb_value(rgb_mixed_match[3])
    return r + g + b
  end

  # Handle named colors
  if NAMED_COLORS.key?(color)
    hex = NAMED_COLORS[color]
    r = hex[1..2].to_i(16)
    g = hex[3..4].to_i(16)
    b = hex[5..6].to_i(16)
    return r + g + b
  end

  nil
end

.rgb_to_hex(red, green, blue) ⇒ Object

Convert RGB values to hex



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# File 'lib/svg_conform/css_color.rb', line 131

def rgb_to_hex(red, green, blue)
  # Clamp values to 0-255 range
  r = [[red.to_i, 0].max, 255].min
  g = [[green.to_i, 0].max, 255].min
  b = [[blue.to_i, 0].max, 255].min

  format("#%02x%02x%02x", r, g, b)
end

.to_canonical(color) ⇒ Object

Convert color to its canonical form (prefer named colors when available)



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# File 'lib/svg_conform/css_color.rb', line 107

def to_canonical(color)
  normalized = normalize(color)
  return color if normalized.nil?

  # Return special keywords as-is
  return normalized if SPECIAL_KEYWORDS.include?(normalized)

  # Convert hex to named color if available
  named = HEX_TO_NAMED[normalized]
  return named if named

  # Return normalized hex
  normalized
end

.valid_css_color?(color) ⇒ Boolean

Check if a color is valid according to SVG specifications

Returns:

  • (Boolean) 


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# File 'lib/svg_conform/css_color.rb', line 141

def valid_css_color?(color)
  return false if color.nil? || color.empty?

  normalized = normalize(color)
  return false if normalized.nil?

  # Valid if it normalizes to something we recognize
  SPECIAL_KEYWORDS.include?(normalized) ||
    NAMED_COLORS.key?(color.strip.downcase) ||
    normalized.match?(/^#[0-9a-f]{6}$/)
end