openproject/app/models/color.rb

#-- encoding: UTF-8
#-- copyright
# OpenProject is an open source project management software.
# Copyright (C) 2012-2020 the OpenProject GmbH
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License version 3.
#
# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
# Copyright (C) 2006-2017 Jean-Philippe Lang
# Copyright (C) 2010-2013 the ChiliProject Team
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
# See docs/COPYRIGHT.rdoc for more details.
#++

class Color < ActiveRecord::Base
  self.table_name = 'colors'

  has_many :planning_element_types, class_name:  'Type',
                                    foreign_key: 'color_id',
                                    dependent:   :nullify

  before_validation :normalize_hexcode

  validates_presence_of :name, :hexcode

  validates_length_of :name, maximum: 255, unless: lambda { |e| e.name.blank? }
  validates_format_of :hexcode, with: /\A#[0-9A-F]{6}\z/, unless: lambda { |e| e.hexcode.blank? }

  ##
  # Returns the best contrasting color, either white or black
  # depending on the overall brightness.
  def contrasting_color(light_color: '#FFFFFF', dark_color: '#333333')
    if bright?
      dark_color
    else
      light_color
    end
  end

  ##
  # Get the fill style for this color.
  # If the color is light, use a dark font.
  # Otherwise, use a white font.
  def color_styles(light_color: '#FFFFFF', dark_color: '#333333')
    if bright?
      { color: dark_color, 'background-color': hexcode }
    else
      { color: light_color, 'background-color': hexcode }
    end
  end

  ##
  # Returns whether the color is bright according to
  # YIQ lightness.
  def bright?
    brightness_yiq >= 128
  end

  ##
  # Returns whether the color is very bright according to
  # YIQ lightness.
  def super_bright?
    brightness_yiq >= 200
  end

  ##
  # Sum the color values of each channel
  # Same as in frontend color-contrast.functions.ts
  def brightness_yiq
    r, g, b = rgb_colors
    ((r * 299) + (g * 587) + (b * 114)) / 1000;
  end

  ##
  # Splits the hexcode into rbg color array
  def rgb_colors
    hexcode
      .gsub('#', '') # Remove trailing #
      .scan(/../) # Pair hex chars
      .map { |c| c.hex } # to int
  end

  protected

  def normalize_hexcode
    if hexcode.present? and hexcode_changed?
      self.hexcode = hexcode.strip.upcase

      unless hexcode.starts_with? '#'
        self.hexcode = '#' + hexcode
      end

      if hexcode.size == 4  # =~ /#.../
        self.hexcode = hexcode.gsub(/([^#])/, '\1\1')
      end
    end
  end
end