Class Color::GrayScale
In: lib/color/grayscale.rb
lib/color.rb
Parent: Object

A colour object representing shades of grey. Used primarily in PDF document creation.

Methods

+   -   ==   brightness   css_hsl   css_hsla   css_rgb   css_rgba   darken_by   from_fraction   from_percent   g   g=   gray   gray=   grey   grey=   html   inspect   lighten_by   new   pdf_fill   pdf_stroke   to_cmyk   to_grayscale   to_greyscale   to_hsl   to_rgb   to_yiq  

Constants

PDF_FORMAT_STR = "%.3f %s"   The format of a DeviceGrey colour for PDF. In color-tools 2.0 this will be removed from this package and added back as a modification by the PDF::Writer package.

Public Class methods

Creates a greyscale colour object from fractional values 0..1.

  Color::GreyScale.from_fraction(0.5)

Creates a greyscale colour object from percentages 0..100.

  Color::GrayScale.from_percent(50)

Creates a greyscale colour object from percentages 0..100.

  Color::GrayScale.new(50)

Public Instance methods

Adds another colour to the current colour. The other colour will be converted to grayscale before addition. This conversion depends upon a to_grayscale method on the other colour.

The addition is done using the grayscale accessor methods to ensure a valid colour in the result.

Subtracts another colour to the current colour. The other colour will be converted to grayscale before subtraction. This conversion depends upon a to_grayscale method on the other colour.

The subtraction is done using the grayscale accessor methods to ensure a valid colour in the result.

Compares the other colour to this one. The other colour will be converted to GreyScale before comparison, so the comparison between a GreyScale colour and a non-GreyScale colour will be approximate and based on the other colour‘s to_greyscale conversion. If there is no to_greyscale conversion, this will raise an exception. This will report that two GreyScale values are equivalent if they are within COLOR_TOLERANCE of each other.

Returns the brightness value for this greyscale value; this is the greyscale value itself.

Present the colour as an HSL HTML/CSS colour string (e.g., "hsl(180, 25%, 35%)"). Note that this will perform a to_hsl operation.

Present the colour as an HSLA (with alpha) HTML/CSS colour string (e.g., "hsla(180, 25%, 35%, 1)"). Note that this will perform a to_hsl operation.

Present the colour as an RGB HTML/CSS colour string (e.g., "rgb(0%, 50%, 100%)").

Present the colour as an RGBA (with alpha) HTML/CSS colour string (e.g., "rgb(0%, 50%, 100%, 1)").

Darken the greyscale colour by the stated percent.

Returns the grayscale value as a fractional value of white in the range 0.0 .. 1.0.

Returns the grayscale value as a fractional value of white in the range 0.0 .. 1.0.

Returns the grayscale value as a percentage of white (100% gray is white).

Sets the grayscale value as a percentage of white.

grey()

Alias for gray

grey=(gg)

Alias for gray=

Present the colour as an HTML/CSS colour string.

Lightens the greyscale colour by the stated percent.

Present the colour as a DeviceGrey fill colour string for PDF. This will be removed from the default package in color-tools 2.0.

Present the colour as a DeviceGrey stroke colour string for PDF. This will be removed from the default package in color-tools 2.0.

Convert the greyscale colour to CMYK.

Reflexive conversion.

to_greyscale()

Alias for to_grayscale

Returns the HSL colour encoding of the greyscale value.

Convert the greyscale colour to RGB.

Returns the YIQ (NTSC) colour encoding of the greyscale value. This is an approximation, as the values for I and Q are calculated by treating the greyscale value as an RGB value. The Y (intensity or brightness) value is the same as the greyscale value.

[Validate]