NAME

       Graphics::Toolkit::Color::Value - check, convert and measure color values

SYNOPSIS

           use Graphics::Toolkit::Color::Value;         # import nothing
           use Graphics::Toolkit::Color::Value ':all';  # import all routines

           check_rgb( 256, 10, 12 ); # throws error 255 is the limit
           my @hsl = hsl_from_rgb( 20, 50, 70 ); # convert from RGB to HSL space

DESCRIPTION

       A set of helper routines to handle RGB and HSL values: bound checks, conversion,
       measurement. Most subs expect three numerical values, or sometimes two triplet. This
       module is supposed to be used by Graphics::Toolkit::Color and not directly.

ROUTINES

   check_rgb
       Carp error message if RGB value triplet is not valid (or out of value range).

   check_hsl
       Carp error message if HSL value triplet is not valid (or out of value range).

   trim_rgb
       Change RGB triplet to the nearest valid values.

   trim_hsl
       Change HSL triplet to the nearest valid values.

   hsl_from_rgb
       Converting an rgb value triplet into the corresponding hsl

       Red, Green and Blue are integer in 0 .. 255.  Hue is an integer between 0 .. 359 (hue) and
       saturation and lightness are 0 .. 100 (percentage).  A hue of 360 and 0 (degree in a
       cylindrical coordinate system) is considered to be the same, this modul deals only with
       the ladder.

   rgb_from_hsl
       Converting an hsl value triplet into the corresponding rgb (see rgb_from_name and
       hsl_from_name). Please not that back and forth conversion can lead to drifting results due
       to rounding.

           my @rgb = rgb_from_hsl( 0, 90, 50 );
           my @rgb = rgb_from_hsl( [0, 90, 50] ); # works too
           # for real (none integer results), any none zero value works as second arg
           my @rgb = rgb_from_hsl( [0, 90, 50], 'real');

   hex_from_rgb
       Converts a red green blue triplet into format: '#RRGGBB'.

   rgb_from_hex
       Converts '#RRGGBB' or '#RGB' hex values into regular RGB triple of 0..255.

   distance_rgb
       Distance in (linear) rgb color space between two coordinates.

           my $d = distance_rgb([1,1,1], [2,2,2]);  # approx 1.7

   distance_hsl
       Distance in (cylindrical) hsl color space between two coordinates.

           my $d = distance_rgb([1,1,1], [356, 3, 2]); # approx 6

COPYRIGHT & LICENSE

       Copyright 2022 Herbert Breunung.

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

AUTHOR

       Herbert Breunung, <lichtkind@cpan.org>