module Xlsxrb::Colors

ECMA-376 Part 4 §18.8.27 Standard Indexed Color Palette and utilities.

Constants

INDEXED_COLORS: Standard ECMA-376 indexed colors (indices 0 through 63 as 6-character RRGGBB hex strings). Indices 8 through 63 represent the classic 56-color palette.

Public Class Methods

(untyped index, ?alpha: bool) → String?

Source

# File lib/xlsxrb/colors.rb, line 88
def self.palette_color(index, alpha: false)
  return nil unless index.is_a?(Integer) && index >= 0 && index < INDEXED_COLORS.size

  hex = INDEXED_COLORS[index]
  alpha ? "FF#{hex}" : hex
end

Resolves a palette index (0..63) to an RRGGBB hex string (or AARRGGBB if alpha: true).

@example

Xlsxrb::Colors.palette_color(12)               #=> "0000FF"
Xlsxrb::Colors.palette_color(12, alpha: true)  #=> "FF0000FF"

@param index [Object, nil] Palette index (0..63). @param alpha [Boolean] Whether to prefix “FF” alpha channel. @return [String, nil] @api public

to_hex (color, alpha: false)

(Integer | String | Symbol | nil color, ?alpha: bool) → String?

Source

# File lib/xlsxrb/colors.rb, line 110
def self.to_hex(color, alpha: false)
  return nil if color.nil?

  return palette_color(color, alpha: alpha) if color.is_a?(Integer) && color >= 0 && color < INDEXED_COLORS.size

  StyleBuilder.normalize_color(color, alpha: alpha)
end

Converts any supported color representation (palette index 0..63, CSS name, #RGB, #RRGGBB, #AARRGGBB, integer RGB) to a normalized hex string.

@example

Xlsxrb::Colors.to_hex(12)                      #=> "0000FF"
Xlsxrb::Colors.to_hex(12, alpha: true)         #=> "FF0000FF"
Xlsxrb::Colors.to_hex(:navy)                   #=> "000080"
Xlsxrb::Colors.to_hex("#FF0000")               #=> "FF0000"
Xlsxrb::Colors.to_hex(0xFF0000)                #=> "FF0000"

@param color [Integer, String, Symbol, nil] @param alpha [Boolean] Whether to include the alpha channel (default false -> “RRGGBB”). @return [String, nil] @api public