Module: Users::AvatarHelper

Includes:
Magick
Defined in:
app/helpers/users/avatar_helper.rb

Instance Method Summary collapse

Instance Method Details

#user_auto_avatar(size, user: nil) ⇒ Magick::Image #user_auto_avatar(size, letter: nil, color: nil) ⇒ Magick::Image

Creates an avatar image based either on a user account or on provided values.

Examples:

Generate an avatar for the current user:

helpers.user_auto_avatar(64, user: current_user)

Generate a generic avatar:

helpers.user_auto_avatar(32, letter: 'A', color: '#3C0FFEE5')

Overloads:

  • #user_auto_avatar(size, user: nil) ⇒ Magick::Image

    Parameters:

    • size (Integer) —

      The side length of the final image, in pixels. O(n^2) at minimum - large values will take exponentially longer to generate.

    • user (User) (defaults to: nil) —

      A user object from which to take the avatar letter and color

  • #user_auto_avatar(size, letter: nil, color: nil) ⇒ Magick::Image

    Parameters:

    • size (Integer) —

      The side length of the final image, in pixels. O(n^2) at minimum - large values will take exponentially longer to generate.

    • letter (String) (defaults to: nil) —

      A single character to display on the avatar if user is not set

    • color (String) (defaults to: nil) —

      An 8-digit hex code, with leading #, to color the avatar background if user is not set

Returns:

  • (Magick::Image) —

    The generated avatar

Raises:

  • (ArgumentError) —

    If a user or letter-color combination is not provided.



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# File 'app/helpers/users/avatar_helper.rb', line 23

def user_auto_avatar(size, user: nil, letter: nil, color: nil)
  raise ArgumentError, 'Either user or letter must be set' if user.nil? && letter.nil?
  raise ArgumentError, 'Color must be set if user is not provided' if user.nil? && color.nil?

  if letter.nil?
    letter = user.username[0]
  end
  if color.nil?
    color = "##{Digest::MD5.hexdigest(user.username)[0...6]}FF"
  end

  cache_key = if user.present?
                "network/avatars/#{user.id}/#{size}px"
              else
                "network/avatars/#{letter}+#{color}/#{size}px"
              end

  Rails.cache.fetch cache_key, include_community: false, expires_in: 24.hours do
    ava = Image.new(size, size)
    text_color = yiq_contrast(color, 'black', 'white')

    bg = Draw.new
    bg.fill color
    bg.rectangle 0, 0, size, size
    bg.draw ava

    let = Draw.new
    let.font_family = 'Roboto'
    let.font_weight = 400
    let.font = './app/assets/imgfonts/Roboto.ttf'
    let.pointsize = size * 0.75
    let.gravity = CenterGravity
    let.annotate ava, size, size * 1.16, 0, 0, letter.upcase do |s|
      s.fill = text_color
    end

    ava.format = 'PNG'
    ava
  end
end

#yiq_contrast(base, on_light, on_dark) ⇒ String

Returns on_light if the given base color is light, and vice versa. Useful for picking a text color to use on a dynamic background. Uses the YIQ color space.

Parameters:

  • base (String) —

    The base/background color on which to base the calculation.

  • on_light (String) —

    The text color to use on a light background.

  • on_dark (String) —

    The text color to use on a dark background.

Returns:

  • (String) —

    The text color to use, either on_light or on_dark.



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# File 'app/helpers/users/avatar_helper.rb', line 71

def yiq_contrast(base, on_light, on_dark)
  base = base[1..]
  red = base[0...2].to_i(16)
  green = base[2...4].to_i(16)
  blue = base[4...6].to_i(16)
  yiq = ((red * 299) + (green * 587) + (blue * 114)) / 1000
  yiq >= 128 ? on_light : on_dark
end