Module: ColorContrastCalc

Defined in:
lib/color_contrast_calc.rb,
lib/color_contrast_calc/shim.rb,
lib/color_contrast_calc/color.rb,
lib/color_contrast_calc/utils.rb,
lib/color_contrast_calc/sorter.rb,
lib/color_contrast_calc/checker.rb,
lib/color_contrast_calc/version.rb,
lib/color_contrast_calc/converter.rb,
lib/color_contrast_calc/deprecated.rb,
lib/color_contrast_calc/threshold_finder.rb,
lib/color_contrast_calc/transparency_calc.rb,
lib/color_contrast_calc/color_function_parser.rb,
lib/color_contrast_calc/invalid_color_representation_error.rb

Defined Under Namespace

Modules: Checker, ColorFunctionParser, Converter, Deprecated, Rgb, Shim, Sorter, ThresholdFinder, TransparencyCalc, Utils Classes: Color, InvalidColorRepresentationError

Constant Summary collapse

VERSION = 
'0.9.0'

Class Method Summary collapse

Class Method Details

.color_from(color_value, name = nil) ⇒ Color

Return an instance of Color.

As color_value, you can pass a predefined color name, an RGB value represented as an array of integers like [255, 255, 0], or a string such as a hex code like “#ffff00”. name is assigned to the returned instance.



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# File 'lib/color_contrast_calc.rb', line 29

def self.color_from(color_value, name = nil)
  Color.color_from(color_value, name)
end

.contrast_ratio(color1, color2) ⇒ Float

Calculate the contrast ratio of given colors.

The definition of contrast ratio is given at https://www.w3.org/TR/2008/REC-WCAG20-20081211/#contrast-ratiodef

Please note that this method may be slow, as it internally creates Color instances.



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# File 'lib/color_contrast_calc.rb', line 75

def self.contrast_ratio(color1, color2)
  Color.as_color(color1).contrast_ratio_against(Color.as_color(color2))
end

.contrast_ratio_with_opacity(foreground, background, base = Color::WHITE) ⇒ Float

Calculate the contrast ratio of transparent colors.

For the calculation, you have to specify three colors because when both of two colors to be compared are transparent, the third color put under them filters through them.



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# File 'lib/color_contrast_calc.rb', line 95

def self.contrast_ratio_with_opacity(foreground, background,
                                     base = Color::WHITE)
  params = [foreground, background, base].map do |c|
    color = Color.as_color(c)
    color.rgb + [color.opacity]
  end

  TransparencyCalc.contrast_ratio(*params)
end

.higher_contrast_base_color_for(color, light_base: Color::WHITE, dark_base: Color::BLACK) ⇒ String, ...

Select from two colors the one of which the contrast ratio is higher than the other’s, against a given color.

Note that this method is tentatively provided and may be changed later including its name.



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# File 'lib/color_contrast_calc.rb', line 123

def self.higher_contrast_base_color_for(color,
                                        light_base: Color::WHITE,
                                        dark_base: Color::BLACK)
  ratio_with_light = contrast_ratio(color, light_base)
  ratio_with_dark = contrast_ratio(color, dark_base)
  ratio_with_light < ratio_with_dark ? dark_base : light_base
end

.hsl_colors(s: 100, l: 50, h_interval: 1) ⇒ Array<Color>

Return a list of colors which share the same saturation and lightness.

By default, so-called pure colors are returned.



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# File 'lib/color_contrast_calc.rb', line 166

def self.hsl_colors(s: 100, l: 50, h_interval: 1)
  Color::List.hsl_colors(s: s, l: l, h_interval: h_interval)
end

.named_colors(frozen: true) ⇒ Array<Color>

Return an array of named colors.

You can find the color names at www.w3.org/TR/SVG/types.html#ColorKeywords



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# File 'lib/color_contrast_calc.rb', line 139

def self.named_colors(frozen: true)
  named_colors = Color::List::NAMED_COLORS
  frozen ? named_colors : named_colors.dup
end

.sort(colors, color_order = 'hSL', key_mapper = nil, &key_mapper_block) ⇒ Array<Color>, Array<String>

Sort colors in the order specified by color_order.

Sort colors given as an array of Color instances or hex color codes. (alias of Sorter.sort())

You can specify sorting order by giving a color_order string, such as “HSL” or “RGB”. A component of color_order on the left side has a higher sorting precedence, and an uppercase letter means descending order.



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# File 'lib/color_contrast_calc.rb', line 52

def self.sort(colors, color_order = 'hSL',
              key_mapper = nil, &key_mapper_block)
  key_mapper = key_mapper_block if !key_mapper && key_mapper_block
  Sorter.sort(colors, color_order, key_mapper)
end

.web_safe_colors(frozen: true) ⇒ Array<Color>

Return an array of web safe colors.



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# File 'lib/color_contrast_calc.rb', line 150

def self.web_safe_colors(frozen: true)
  colors = Color::List::WEB_SAFE_COLORS
  frozen ? colors : colors.dup
end