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Graphics::Toolkit::Color::Values(3) User Contributed Perl Documentation Graphics::Toolkit::Color::Values(3)


Graphics::Toolkit::Color::Value - single color related high level methods


Readonly object that holds values of a color. It provides methods to get the values back in different formats, to measure difference to other colors or to create value objects of related colors.

    use Graphics::Toolkit::Color::Value;
    my $blue = Graphics::Toolkit::Color::Value->new( 'hsl(220,50,60)' );
    my @rgb = $blue->get();
    my $purple = $blue->set({red => 220});


The object that holds the normalized values of the original color definition (getter argument) and the normalized RGB tripled, if the color was not defined in RGB values. This way we omit conversion and rounding errors as much as possible.

This package is a mediation layer between Graphics::Toolkit::Color::Space::Hub below, where its just about number crunching of value vectors and the user API above in Graphics::Toolkit::Color, where it's mainly about producing sets of colors and handling the arguments. This module is not meant to be used as an public API since it has much less comfort than Graphics::Toolkit::Color.



The constructor takes only one required argument, a scalar that completely and numerically defines a color. Inside color definitions are color space names case insensitive. Some possible formats are

    [ 1, 2, 3 ]                  # RGB triplet
    [ HSL => 220, 100, 3 ]       # named HSL vector
    { h => 220, s =>100, l => 3} # char hash
    { cyan => 1, magenta => 0.5, yellow => 0} # hash
    'hwb: 20, 60, 30'            # string
    'hwb(20,60,30)'              # css_string
    '#2211FF'                    # rgb hex string


Universal getter method -almost reverse function to new: It can return the colors values in all supported color spaces (first argument) (see: "COLOR-SPACES" in Graphics::Toolkit::Color::Space::Hub) and all mentioned formats above (second argument). Additionally a third arguments can convert the numerical values into different ranges. The default name space is RGB, default format is a list and every color space has its default range.

    my @rgb = $val_object->get();
    my @cmyk = $val_object->get('CMYK', 'list', 255);
    my $YIQ = $val_object->get('YIQ', 'string');


Constructs a new "Graphics::Toolkit::Color::Value" object by absolutely changing some values of the current object and keeping others. (add changes some values relatively.) The only and required argument is a HASH reference which has keys that match only one of the supported color spaces (see: "COLOR-SPACES" in Graphics::Toolkit::Color::Space::Hub). Values outside of the defined limits will be clamped to an acceptable value (or rotated in case of circular dimensions).

    my $more_blend_color = $val_object->set( {saturation => 40} );
    my $bright_color = $val_object->set( {saturation => 2240} ); #saturation will be 100


This method takes also a HASH reference as input and also produces a related color object as previous set. Only difference is: the hash values will be added to the current. If they go outside of the defined limits, they will be clamped (or rotated in case of circular dimensions).

    my $darker_color = $val_object->set( {lightness => -10} );


Creates a color value object by mixing two colors. First and only required argument is the second color value object. Second argument is the mixing ratio. Zero would result in the original color and one to the second color. Default value is 0.5 (1:1 mix). Values outside the 0..1 rande are possible and values will be clamped if they leave the defined bounds of the required color space.

Third optional argument is the name of the color space the mix will be calculated in - it defaults to 'HSL'.

    my $green = Graphics::Toolkit::Color::Values->new( '#00ff00' );
    my $cyan = $blue->blend( $green, 0.6, 'YIQ' );


Computes a real number which designates the (Euclidean) distance between two points in a color space (a.k.a. colors).

The first and only required argument is the second color as an Graphics::Toolkit::Color::Value object. Second and optional argument is the name of the color space, where the distance is calculated in (default is 'HSL'). Third argument is the metric, which currently is just the subset of dimension in the chosen space that should be observed. One can also mention the shortcut name of a dimension several times to increase their weight in the calculation. Fourth optional argument are the numeric ranges of the dimensions. If none are given, the method only uses normalised (range: 0..1) values.

    my $blue = Graphics::Toolkit::Color::Values->new( '#0000ff' );
    my $green = Graphics::Toolkit::Color::Values->new( '#00ff00' );
    my $d = $blue->distance( $green, 'HSV', 's', 255); # 0 : both have same saturation




Copyright 2023 Herbert Breunung.

This program is free software; you can redistribute it and/or modify it under same terms as Perl itself.


Herbert Breunung, <>

2024-03-08 perl v5.40.0