Class: Unmagic::Color::RGB::Hex

Inherits:
Object
  • Object
show all
Defined in:
lib/unmagic/color/rgb/hex.rb

Overview

Hexadecimal color parsing utilities.

Hex colors are a compact way to write Unmagic::Color::RGB values using hexadecimal (base-16) notation. Each pair of hex digits represents one color component (‘0-255`).

## Understanding Hexadecimal

Hexadecimal uses 16 digits: ‘0-9` and `A-F`

  • ‘0 = 0`, `9 = 9`, `A = 10`, `B = 11`, … `F = 15`

  • Two hex digits can represent ‘0-255` (`16 × 16 = 256` values)

  • ‘FF = 255`, `00 = 0`, `80 = 128`, etc.

## Hex Color Format

  • **Full format**: ‘#RRGGBB` (6 digits, 2 per component)

  • **Short format**: ‘#RGB` (3 digits, each digit is doubled)

  • **Hash optional**: Can be written with or without the ‘#` prefix

## Examples

  • ‘#FF0000` = Red (`255, 0, 0`)

  • ‘#00FF00` = Green (`0, 255, 0`)

  • ‘#0000FF` = Blue (`0, 0, 255`)

  • ‘#F00` = `#FF0000` (short form)

  • ‘#ABC` = `#AABBCC` (short form expanded)

Defined Under Namespace

Classes: ParseError

Class Method Summary collapse

Class Method Details

.parse(input) ⇒ RGB

Parse a hexadecimal color string.

Accepts full (6-digit) and short (3-digit) hex formats, with or without the # prefix. Also supports 8-digit (with alpha) and 4-digit short format with alpha.

Examples:

Full format with hash

Unmagic::Color::RGB::Hex.parse("#FF8800")

Short format without hash

Unmagic::Color::RGB::Hex.parse("F80")

With alpha

Unmagic::Color::RGB::Hex.parse("#FF880080")

Parameters:

  • input (String) —

    The hex color string to parse

Returns:

  • (RGB) —

    The parsed RGB color

Raises:

  • (ParseError) —

    If the input is not a valid hex color



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# File 'lib/unmagic/color/rgb/hex.rb', line 76

def parse(input)
  raise ParseError, "Input must be a string" unless input.is_a?(::String)

  # Clean up the input
  hex = input.strip.gsub(/^#/, "")

  # Check for valid length (3, 4, 6, or 8 characters)
  unless [3, 4, 6, 8].include?(hex.length)
    raise ParseError, "Invalid number of characters (got #{hex.length}, expected 3, 4, 6, or 8)"
  end

  # Check if all characters are valid hex digits
  unless hex.match?(/\A[0-9A-Fa-f]+\z/)
    invalid_chars = hex.chars.reject { |c| c.match?(/[0-9A-Fa-f]/) }
    raise ParseError, "Invalid hex characters: #{invalid_chars.join(", ")}"
  end

  # Handle 3 or 4-character hex codes (expand each digit)
  if hex.length == 3 || hex.length == 4
    hex = hex.chars.map { |c| c * 2 }.join
  end

  r = hex[0..1].to_i(16)
  g = hex[2..3].to_i(16)
  b = hex[4..5].to_i(16)

  # Parse alpha if present (8 characters total after expansion)
  if hex.length == 8
    a = hex[6..7].to_i(16)
    # Convert 0-255 alpha to 0-100 percentage
    alpha_percent = (a / 255.0 * 100).round(2)
    RGB.build(red: r, green: g, blue: b, alpha: alpha_percent)
  else
    RGB.build(red: r, green: g, blue: b)
  end
end

.valid?(value) ⇒ Boolean

Check if a string is a valid hex color.

Examples:

Unmagic::Color::RGB::Hex.valid?("#FF5733")
# => true

Unmagic::Color::RGB::Hex.valid?("F73")
# => true

Unmagic::Color::RGB::Hex.valid?("GGGGGG")
# => false

Parameters:

  • value (String) —

    The string to validate

Returns:

  • (Boolean) —

    true if valid hex color, false otherwise



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# File 'lib/unmagic/color/rgb/hex.rb', line 51

def valid?(value)
  parse(value)
  true
rescue ParseError
  false
end