lib/Mail/SpamAssassin/HTML/Color.pm - spamassassin - Git at Google

 # <@LICENSE>
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.
 # The ASF licenses this file to you under the Apache License, Version 2.0
 # (the "License"); you may not use this file except in compliance with
 # the License.  You may obtain a copy of the License at:
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
 # </@LICENSE>

 package Mail::SpamAssassin::HTML::Color;
 use strict;
 use warnings;
 no warnings 'numeric';
 use Carp qw(croak);
 use overload '""' => sub { shift->as_hex }, fallback => 1;

 my %html_color = (
     # HTML 4 defined 16 colors
     aqua => [0, 255, 255],
     black => [0, 0, 0],
     blue => [0, 0, 255],
     fuchsia => [255, 0, 255],
     gray => [128, 128, 128],
     green => [0, 128, 0],
     lime => [0, 255, 0],
     maroon => [128, 0, 0],
     navy => [0, 0, 128],
     olive => [128, 128, 0],
     purple => [128, 0, 128],
     red => [255, 0, 0],
     silver => [192, 192, 192],
     teal => [0, 128, 128],
     white => [255, 255, 255],
     yellow => [255, 255, 0],
     # colors specified in CSS3 color module
     aliceblue => [240, 248, 255],
     antiquewhite => [250, 235, 215],
     aquamarine => [127, 255, 212],
     azure => [240, 255, 255],
     beige => [245, 245, 220],
     bisque => [255, 228, 196],
     blanchedalmond => [255, 235, 205],
     blueviolet => [138, 43, 226],
     brown => [165, 42, 42],
     burlywood => [222, 184, 135],
     cadetblue => [95, 158, 160],
     chartreuse => [127, 255, 0],
     chocolate => [210, 105, 30],
     coral => [255, 127, 80],
     cornflowerblue => [100, 149, 237],
     cornsilk => [255, 248, 220],
     crimson => [220, 20, 60],
     cyan => [0, 255, 255],
     darkblue => [0, 0, 139],
     darkcyan => [0, 139, 139],
     darkgoldenrod => [184, 134, 11],
     darkgray => [169, 169, 169],
     darkgreen => [0, 100, 0],
     darkkhaki => [189, 183, 107],
     darkmagenta => [139, 0, 139],
     darkolivegreen => [85, 107, 47],
     darkorange => [255, 140, 0],
     darkorchid => [153, 50, 204],
     darkred => [139, 0, 0],
     darksalmon => [233, 150, 122],
     darkseagreen => [143, 188, 143],
     darkslateblue => [72, 61, 139],
     darkslategray => [47, 79, 79],
     darkturquoise => [0, 206, 209],
     darkviolet => [148, 0, 211],
     deeppink => [255, 20, 147],
     deepskyblue => [0, 191, 255],
     dimgray => [105, 105, 105],
     dodgerblue => [30, 144, 255],
     firebrick => [178, 34, 34],
     floralwhite => [255, 250, 240],
     forestgreen => [34, 139, 34],
     gainsboro => [220, 220, 220],
     ghostwhite => [248, 248, 255],
     gold => [255, 215, 0],
     goldenrod => [218, 165, 32],
     greenyellow => [173, 255, 47],
     honeydew => [240, 255, 240],
     hotpink => [255, 105, 180],
     indianred => [205, 92, 92],
     indigo => [75, 0, 130],
     ivory => [255, 255, 240],
     khaki => [240, 230, 140],
     lavender => [230, 230, 250],
     lavenderblush => [255, 240, 245],
     lawngreen => [124, 252, 0],
     lemonchiffon => [255, 250, 205],
     lightblue => [173, 216, 230],
     lightcoral => [240, 128, 128],
     lightcyan => [224, 255, 255],
     lightgoldenrodyellow => [250, 250, 210],
     lightgray => [211, 211, 211],
     lightgreen => [144, 238, 144],
     lightpink => [255, 182, 193],
     lightsalmon => [255, 160, 122],
     lightseagreen => [32, 178, 170],
     lightskyblue => [135, 206, 250],
     lightslategray => [119, 136, 153],
     lightsteelblue => [176, 196, 222],
     lightyellow => [255, 255, 224],
     limegreen => [50, 205, 50],
     linen => [250, 240, 230],
     magenta => [255, 0, 255],
     mediumaquamarine => [102, 205, 170],
     mediumblue => [0, 0, 205],
     mediumorchid => [186, 85, 211],
     mediumpurple => [147, 112, 219],
     mediumseagreen => [60, 179, 113],
     mediumslateblue => [123, 104, 238],
     mediumspringgreen => [0, 250, 154],
     mediumturquoise => [72, 209, 204],
     mediumvioletred => [199, 21, 133],
     midnightblue => [25, 25, 112],
     mintcream => [245, 255, 250],
     mistyrose => [255, 228, 225],
     moccasin => [255, 228, 181],
     navajowhite => [255, 222, 173],
     oldlace => [253, 245, 230],
     olivedrab => [107, 142, 35],
     orange => [255, 165, 0],
     orangered => [255, 69, 0],
     orchid => [218, 112, 214],
     palegoldenrod => [238, 232, 170],
     palegreen => [152, 251, 152],
     paleturquoise => [175, 238, 238],
     palevioletred => [219, 112, 147],
     papayawhip => [255, 239, 213],
     peachpuff => [255, 218, 185],
     peru => [205, 133, 63],
     pink => [255, 192, 203],
     plum => [221, 160, 221],
     powderblue => [176, 224, 230],
     rosybrown => [188, 143, 143],
     royalblue => [65, 105, 225],
     saddlebrown => [139, 69, 19],
     salmon => [250, 128, 114],
     sandybrown => [244, 164, 96],
     seagreen => [46, 139, 87],
     seashell => [255, 245, 238],
     sienna => [160, 82, 45],
     skyblue => [135, 206, 235],
     slateblue => [106, 90, 205],
     slategray => [112, 128, 144],
     snow => [255, 250, 250],
     springgreen => [0, 255, 127],
     steelblue => [70, 130, 180],
     tan => [210, 180, 140],
     thistle => [216, 191, 216],
     tomato => [255, 99, 71],
     turquoise => [64, 224, 208],
     violet => [238, 130, 238],
     wheat => [245, 222, 179],
     whitesmoke => [245, 245, 245],
     yellowgreen => [154, 205, 50],
 );

 sub new {
     my ($class, $color) = @_;
     my $self = [];
     bless $self, $class;

     croak("Color value is required") unless (defined $color);
     $color =~ s/^\s+|\s+$//g;  # Trim whitespace
     $color = lc($color);

     # If color is 'transparent', set all values to 0
     if ($color eq 'transparent') {
         @$self = (0, 0, 0, 0);
         return $self;
     }

     # Check if color is a named color
     if (exists $html_color{$color}) {
         @$self = (@{ $html_color{$color} }, 1);
         return $self;
     }

     # Check if color is in hexadecimal format (#000 or #aabbcc)
     if ($color =~ /^#([0-9a-f]{3}|[0-9a-f]{6})$/) {
         my $hex = length($1) == 3
                 ? join('', map { $_ x 2 } split //, $1)
                 : $1;
         @$self = map { hex($_) } $hex =~ /../g;
         push @$self, 1;
         return $self;
     }

     # Check if color is in RGB format (rgb(255, 0, 153) or rgb(255 0 153 / 80%))
     if ($color =~ /^rgba?\s*\((.*)\)$/) {
         my @args = split(/[ ,\/]+/, $1);
         push @args, 1 if @args == 3;
         croak("Invalid number of arguments for RGB color") unless @args == 4;
         for (@args) {
             croak("Invalid RGB value: $_") unless $_ =~ /^(?:none|[+-]?\d*\.?\d+%?)$/;
         }
         my ($r, $g, $b) = map {
             /^(.*)%$/ ? _round($1 * 255 / 100) : $_ + 0;
         } @args[0..2];
         $a = $args[3];
         $a = $a =~ s/%$// ? $a / 100 : $a + 0;
         @$self = ($r, $g, $b, $a);
         return $self;
     }

     # Check if color is in HSL format (hsl(360, 100%, 50%) or hsl(360 100% 50% / 80%))
     if ($color =~ /^hsla?\s*\((.*)\)$/) {
         my @args = split(/[ ,\/]+/, $1);
         push @args, 1 if @args == 3;
         croak("Invalid number of arguments for HSL color") unless @args == 4;
         for (@args[1..3]) {
             croak("Invalid HSL value: $_") unless $_ =~ /^(?:none|[+-]?\d*\.?\d+%?)$/;
         }
         my ($h, $s, $l, $a) = @args;
         $h = _parse_angle($h);
         $s =~ s/%$//; $s /= 100;
         $l =~ s/%$//; $l /= 100;
         $a = $a =~ s/%$// ? $a / 100 : $a + 0;

         @$self = _hsl_to_rgb($h, $s, $l);
         push @$self, $a;
         return $self;
     }

     # Check if color is in HWB format (hwb(240, 100%, 0%) or hwb(240 100% 0% / 80%))
     if ($color =~ /^hwba?\s*\((.*)\)$/) {
         my @args = split(/[ ,\/]+/, $1);
         push @args, 1 if @args == 3;
         croak("Invalid number of arguments for HWB color") unless @args == 4;
         for (@args[1..3]) {
             croak("Invalid HWB value: $_") unless $_ =~ /^(?:none|[+-]?\d*\.?\d+%?)$/;
         }
         my ($h, $wh, $bl, $a) = @args;
         $h = _parse_angle($h);
         $wh =~ s/%$//; $wh /= 100;
         $bl =~ s/%$//; $bl /= 100;
         $a = $a =~ s/%$// ? $a / 100 : $a + 0;

         @$self = _hwb_to_rgb($h, $wh, $bl);
         push @$self, $a;
         return $self;
     }

     croak("Unsupported color format: $color");
 }

 sub blend {
     my ($self, $background) = @_;
     my ($r, $g, $b, $a) = @$self;
     return $self if $a == 1;
     my ($br, $bg, $bb) = @$background;

     my $new_r = _round(($r * $a) + ($br * (1 - $a)));
     my $new_g = _round(($g * $a) + ($bg * (1 - $a)));
     my $new_b = _round(($b * $a) + ($bb * (1 - $a)));

     @$self = ($new_r, $new_g, $new_b, 1);
     return $self;
 }

 sub distance {
     my ($self, $other_color) = @_;
     my ($r1, $g1, $b1) = @$self[0..2];
     my ($r2, $g2, $b2) = @$other_color[0..2];

     my $r = ($r1 - $r2);
     my $g = ($g1 - $g2);
     my $b = ($b1 - $b2);

     # geometric distance weighted by brightness
     # maximum distance is 191.151823601032
     my $distance = ((0.2126 * $r)**2 + (0.7152 * $g)**2 + (0.0722 * $b)**2)**0.5;

     return $distance;
 }

 sub as_hex {
     my ($self) = @_;
     my ($r, $g, $b) = @$self[0..2];
     return sprintf("#%02x%02x%02x", $r, $g, $b);
 }

 sub as_array {
     my ($self) = @_;
     return @$self;
 }

 #
 # Static Private Methods
 #

 sub _hsl_to_rgb {
     my ($hue, $saturation, $lightness) = @_;

     # Ensure the hue is between 0-360 degrees and S, L are between 0 and 1
     $hue %= 360;
     $saturation = 0 if $saturation < 0;
     $lightness = 0 if $lightness < 0;
     $saturation = 1 if $saturation > 1;
     $lightness = 1 if $lightness > 1;

     my $c = (1 - abs(2 * $lightness - 1)) * $saturation;
     my $x = $c * (1 - abs(($hue / 60) % 2 - 1));
     my $m = $lightness - $c / 2;
     my @rgb;

     if ($hue >= 0 && $hue < 60) {
         @rgb = ($c, $x, 0);
     } elsif ($hue >= 60 && $hue < 120) {
         @rgb = ($x, $c, 0);
     } elsif ($hue >= 120 && $hue < 180) {
         @rgb = (0, $c, $x);
     } elsif ($hue >= 180 && $hue < 240) {
         @rgb = (0, $x, $c);
     } elsif ($hue >= 240 && $hue < 300) {
         @rgb = ($x, 0, $c);
     } else {
         @rgb = ($c, 0, $x);
     }

     return map { _round(($_ + $m) * 255) } @rgb;
 }

 sub _hwb_to_rgb {
     my ($hue, $whiteness, $blackness) = @_;

     # Ensure the hue is between 0-360 degrees and W, B are between 0 and 1
     $hue %= 360;
     $whiteness = 0 if $whiteness < 0;
     $blackness = 0 if $blackness < 0;
     $whiteness = 1 if $whiteness > 1;
     $blackness = 1 if $blackness > 1;

     # Convert hue to range 0 to 1
     my $h = $hue / 60;  # Divide hue by 60 to put it in [0, 6)
     my $f = $h - int($h);
     my @rgb_base;

     # Get RGB base values based on hue
     if    ($h < 1) { @rgb_base = (1, $f, 0); }
     elsif ($h < 2) { @rgb_base = (1 - $f, 1, 0); }
     elsif ($h < 3) { @rgb_base = (0, 1, $f); }
     elsif ($h < 4) { @rgb_base = (0, 1 - $f, 1); }
     elsif ($h < 5) { @rgb_base = ($f, 0, 1); }
     else           { @rgb_base = (1, 0, 1 - $f); }

     # Apply whiteness and blackness to compute final RGB values
     my $i = 1 - $whiteness - $blackness;
     my @rgb = map { _round(($whiteness + $i * $_) * 255) } @rgb_base;

     return @rgb;
 }

 sub _parse_angle {
     my ($angle) = @_;

     croak("Invalid color angle: $angle") unless $angle =~ /^(?:none|[+-]?\d*\.?\d+(?:deg|grad|rad|turn)?)$/;

     $angle = $angle =~ s/deg$// ? $angle
         : $angle =~ s/grad$// ? $angle * 360 / 400
         : $angle =~ s/rad$// ? $angle * 180 / 3.14159
         : $angle =~ s/turn$// ? $angle * 360
         : $angle;

     return _round($angle) % 360;

 }

 sub _round {
     my ($value) = @_;
     return int($value + 0.5);
 }

 1;

 __END__

 =head1 NAME

 Mail::SpamAssassin::HTML::Color - A class to parse and manipulate CSS color values

 =head1 SYNOPSIS

   use Mail::SpamAssassin::HTML::Color;

   my $color = Mail::SpamAssassin::HTML::Color->new('rgba(255, 0, 153, 0.5)');
   $color->blend([255, 255, 255]);
   my $distance = $color->distance([0, 0, 0]);
   print "$color";  # Outputs the color as a hex string

 =head1 DESCRIPTION

 This class provides methods to parse various CSS color formats, blend them with a background color, calculate the distance between two colors, and convert the color to a hex string.

 =head1 METHODS

 =head2 new($color)

 Creates a new color object from a CSS color string.

 =head2 blend($background)

 Blends the color with the given background color. Modifies the color in-place and returns the modified object.

 =head2 distance($other_color)

 Calculates the distance between the current color and another color using a brightness-weighted geometric formula.

 =head2 as_hex

 Returns the color as a hex string with a leading '#'.

 =head2 as_array

 Returns the color as an array of RGB values.

 =cut
	# <@LICENSE>
	# Licensed to the Apache Software Foundation (ASF) under one or more
	# contributor license agreements. See the NOTICE file distributed with
	# this work for additional information regarding copyright ownership.
	# The ASF licenses this file to you under the Apache License, Version 2.0
	# (the "License"); you may not use this file except in compliance with
	# the License. You may obtain a copy of the License at:
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS,
	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	# See the License for the specific language governing permissions and
	# limitations under the License.
	# </@LICENSE>

	package Mail::SpamAssassin::HTML::Color;
	use strict;
	use warnings;
	no warnings 'numeric';
	use Carp qw(croak);
	use overload '""' => sub { shift->as_hex }, fallback => 1;

	my %html_color = (
	# HTML 4 defined 16 colors
	aqua => [0, 255, 255],
	black => [0, 0, 0],
	blue => [0, 0, 255],
	fuchsia => [255, 0, 255],
	gray => [128, 128, 128],
	green => [0, 128, 0],
	lime => [0, 255, 0],
	maroon => [128, 0, 0],
	navy => [0, 0, 128],
	olive => [128, 128, 0],
	purple => [128, 0, 128],
	red => [255, 0, 0],
	silver => [192, 192, 192],
	teal => [0, 128, 128],
	white => [255, 255, 255],
	yellow => [255, 255, 0],
	# colors specified in CSS3 color module
	aliceblue => [240, 248, 255],
	antiquewhite => [250, 235, 215],
	aquamarine => [127, 255, 212],
	azure => [240, 255, 255],
	beige => [245, 245, 220],
	bisque => [255, 228, 196],
	blanchedalmond => [255, 235, 205],
	blueviolet => [138, 43, 226],
	brown => [165, 42, 42],
	burlywood => [222, 184, 135],
	cadetblue => [95, 158, 160],
	chartreuse => [127, 255, 0],
	chocolate => [210, 105, 30],
	coral => [255, 127, 80],
	cornflowerblue => [100, 149, 237],
	cornsilk => [255, 248, 220],
	crimson => [220, 20, 60],
	cyan => [0, 255, 255],
	darkblue => [0, 0, 139],
	darkcyan => [0, 139, 139],
	darkgoldenrod => [184, 134, 11],
	darkgray => [169, 169, 169],
	darkgreen => [0, 100, 0],
	darkkhaki => [189, 183, 107],
	darkmagenta => [139, 0, 139],
	darkolivegreen => [85, 107, 47],
	darkorange => [255, 140, 0],
	darkorchid => [153, 50, 204],
	darkred => [139, 0, 0],
	darksalmon => [233, 150, 122],
	darkseagreen => [143, 188, 143],
	darkslateblue => [72, 61, 139],
	darkslategray => [47, 79, 79],
	darkturquoise => [0, 206, 209],
	darkviolet => [148, 0, 211],
	deeppink => [255, 20, 147],
	deepskyblue => [0, 191, 255],
	dimgray => [105, 105, 105],
	dodgerblue => [30, 144, 255],
	firebrick => [178, 34, 34],
	floralwhite => [255, 250, 240],
	forestgreen => [34, 139, 34],
	gainsboro => [220, 220, 220],
	ghostwhite => [248, 248, 255],
	gold => [255, 215, 0],
	goldenrod => [218, 165, 32],
	greenyellow => [173, 255, 47],
	honeydew => [240, 255, 240],
	hotpink => [255, 105, 180],
	indianred => [205, 92, 92],
	indigo => [75, 0, 130],
	ivory => [255, 255, 240],
	khaki => [240, 230, 140],
	lavender => [230, 230, 250],
	lavenderblush => [255, 240, 245],
	lawngreen => [124, 252, 0],
	lemonchiffon => [255, 250, 205],
	lightblue => [173, 216, 230],
	lightcoral => [240, 128, 128],
	lightcyan => [224, 255, 255],
	lightgoldenrodyellow => [250, 250, 210],
	lightgray => [211, 211, 211],
	lightgreen => [144, 238, 144],
	lightpink => [255, 182, 193],
	lightsalmon => [255, 160, 122],
	lightseagreen => [32, 178, 170],
	lightskyblue => [135, 206, 250],
	lightslategray => [119, 136, 153],
	lightsteelblue => [176, 196, 222],
	lightyellow => [255, 255, 224],
	limegreen => [50, 205, 50],
	linen => [250, 240, 230],
	magenta => [255, 0, 255],
	mediumaquamarine => [102, 205, 170],
	mediumblue => [0, 0, 205],
	mediumorchid => [186, 85, 211],
	mediumpurple => [147, 112, 219],
	mediumseagreen => [60, 179, 113],
	mediumslateblue => [123, 104, 238],
	mediumspringgreen => [0, 250, 154],
	mediumturquoise => [72, 209, 204],
	mediumvioletred => [199, 21, 133],
	midnightblue => [25, 25, 112],
	mintcream => [245, 255, 250],
	mistyrose => [255, 228, 225],
	moccasin => [255, 228, 181],
	navajowhite => [255, 222, 173],
	oldlace => [253, 245, 230],
	olivedrab => [107, 142, 35],
	orange => [255, 165, 0],
	orangered => [255, 69, 0],
	orchid => [218, 112, 214],
	palegoldenrod => [238, 232, 170],
	palegreen => [152, 251, 152],
	paleturquoise => [175, 238, 238],
	palevioletred => [219, 112, 147],
	papayawhip => [255, 239, 213],
	peachpuff => [255, 218, 185],
	peru => [205, 133, 63],
	pink => [255, 192, 203],
	plum => [221, 160, 221],
	powderblue => [176, 224, 230],
	rosybrown => [188, 143, 143],
	royalblue => [65, 105, 225],
	saddlebrown => [139, 69, 19],
	salmon => [250, 128, 114],
	sandybrown => [244, 164, 96],
	seagreen => [46, 139, 87],
	seashell => [255, 245, 238],
	sienna => [160, 82, 45],
	skyblue => [135, 206, 235],
	slateblue => [106, 90, 205],
	slategray => [112, 128, 144],
	snow => [255, 250, 250],
	springgreen => [0, 255, 127],
	steelblue => [70, 130, 180],
	tan => [210, 180, 140],
	thistle => [216, 191, 216],
	tomato => [255, 99, 71],
	turquoise => [64, 224, 208],
	violet => [238, 130, 238],
	wheat => [245, 222, 179],
	whitesmoke => [245, 245, 245],
	yellowgreen => [154, 205, 50],
	);

	sub new {
	my ($class, $color) = @_;
	my $self = [];
	bless $self, $class;

	croak("Color value is required") unless (defined $color);
	$color =~ s/^\s+\|\s+$//g; # Trim whitespace
	$color = lc($color);

	# If color is 'transparent', set all values to 0
	if ($color eq 'transparent') {
	@$self = (0, 0, 0, 0);
	return $self;
	}

	# Check if color is a named color
	if (exists $html_color{$color}) {
	@$self = (@{ $html_color{$color} }, 1);
	return $self;
	}

	# Check if color is in hexadecimal format (#000 or #aabbcc)
	if ($color =~ /^#([0-9a-f]{3}\|[0-9a-f]{6})$/) {
	my $hex = length($1) == 3
	? join('', map { $_ x 2 } split //, $1)
	: $1;
	@$self = map { hex($_) } $hex =~ /../g;
	push @$self, 1;
	return $self;
	}

	# Check if color is in RGB format (rgb(255, 0, 153) or rgb(255 0 153 / 80%))
	if ($color =~ /^rgba?\s\((.)\)$/) {
	my @args = split(/[ ,\/]+/, $1);
	push @args, 1 if @args == 3;
	croak("Invalid number of arguments for RGB color") unless @args == 4;
	for (@args) {
	croak("Invalid RGB value: $_") unless $_ =~ /^(?:none\|[+-]?\d*\.?\d+%?)$/;
	}
	my ($r, $g, $b) = map {
	/^(.)%$/ ? _round($1 255 / 100) : $_ + 0;
	} @args[0..2];
	$a = $args[3];
	$a = $a =~ s/%$// ? $a / 100 : $a + 0;
	@$self = ($r, $g, $b, $a);
	return $self;
	}

	# Check if color is in HSL format (hsl(360, 100%, 50%) or hsl(360 100% 50% / 80%))
	if ($color =~ /^hsla?\s\((.)\)$/) {
	my @args = split(/[ ,\/]+/, $1);
	push @args, 1 if @args == 3;
	croak("Invalid number of arguments for HSL color") unless @args == 4;
	for (@args[1..3]) {
	croak("Invalid HSL value: $_") unless $_ =~ /^(?:none\|[+-]?\d*\.?\d+%?)$/;
	}
	my ($h, $s, $l, $a) = @args;
	$h = _parse_angle($h);
	$s =~ s/%$//; $s /= 100;
	$l =~ s/%$//; $l /= 100;
	$a = $a =~ s/%$// ? $a / 100 : $a + 0;

	@$self = _hsl_to_rgb($h, $s, $l);
	push @$self, $a;
	return $self;
	}

	# Check if color is in HWB format (hwb(240, 100%, 0%) or hwb(240 100% 0% / 80%))
	if ($color =~ /^hwba?\s\((.)\)$/) {
	my @args = split(/[ ,\/]+/, $1);
	push @args, 1 if @args == 3;
	croak("Invalid number of arguments for HWB color") unless @args == 4;
	for (@args[1..3]) {
	croak("Invalid HWB value: $_") unless $_ =~ /^(?:none\|[+-]?\d*\.?\d+%?)$/;
	}
	my ($h, $wh, $bl, $a) = @args;
	$h = _parse_angle($h);
	$wh =~ s/%$//; $wh /= 100;
	$bl =~ s/%$//; $bl /= 100;
	$a = $a =~ s/%$// ? $a / 100 : $a + 0;

	@$self = _hwb_to_rgb($h, $wh, $bl);
	push @$self, $a;
	return $self;
	}

	croak("Unsupported color format: $color");
	}

	sub blend {
	my ($self, $background) = @_;
	my ($r, $g, $b, $a) = @$self;
	return $self if $a == 1;
	my ($br, $bg, $bb) = @$background;

	my $new_r = _round(($r * $a) + ($br * (1 - $a)));
	my $new_g = _round(($g * $a) + ($bg * (1 - $a)));
	my $new_b = _round(($b * $a) + ($bb * (1 - $a)));

	@$self = ($new_r, $new_g, $new_b, 1);
	return $self;
	}

	sub distance {
	my ($self, $other_color) = @_;
	my ($r1, $g1, $b1) = @$self[0..2];
	my ($r2, $g2, $b2) = @$other_color[0..2];

	my $r = ($r1 - $r2);
	my $g = ($g1 - $g2);
	my $b = ($b1 - $b2);

	# geometric distance weighted by brightness
	# maximum distance is 191.151823601032
	my $distance = ((0.2126 * $r)*2 + (0.7152 $g)*2 + (0.0722 $b)2)0.5;

	return $distance;
	}

	sub as_hex {
	my ($self) = @_;
	my ($r, $g, $b) = @$self[0..2];
	return sprintf("#%02x%02x%02x", $r, $g, $b);
	}

	sub as_array {
	my ($self) = @_;
	return @$self;
	}

	#
	# Static Private Methods
	#

	sub _hsl_to_rgb {
	my ($hue, $saturation, $lightness) = @_;

	# Ensure the hue is between 0-360 degrees and S, L are between 0 and 1
	$hue %= 360;
	$saturation = 0 if $saturation < 0;
	$lightness = 0 if $lightness < 0;
	$saturation = 1 if $saturation > 1;
	$lightness = 1 if $lightness > 1;

	my $c = (1 - abs(2 * $lightness - 1)) * $saturation;
	my $x = $c * (1 - abs(($hue / 60) % 2 - 1));
	my $m = $lightness - $c / 2;
	my @rgb;

	if ($hue >= 0 && $hue < 60) {
	@rgb = ($c, $x, 0);
	} elsif ($hue >= 60 && $hue < 120) {
	@rgb = ($x, $c, 0);
	} elsif ($hue >= 120 && $hue < 180) {
	@rgb = (0, $c, $x);
	} elsif ($hue >= 180 && $hue < 240) {
	@rgb = (0, $x, $c);
	} elsif ($hue >= 240 && $hue < 300) {
	@rgb = ($x, 0, $c);
	} else {
	@rgb = ($c, 0, $x);
	}

	return map { _round(($_ + $m) * 255) } @rgb;
	}

	sub _hwb_to_rgb {
	my ($hue, $whiteness, $blackness) = @_;

	# Ensure the hue is between 0-360 degrees and W, B are between 0 and 1
	$hue %= 360;
	$whiteness = 0 if $whiteness < 0;
	$blackness = 0 if $blackness < 0;
	$whiteness = 1 if $whiteness > 1;
	$blackness = 1 if $blackness > 1;

	# Convert hue to range 0 to 1
	my $h = $hue / 60; # Divide hue by 60 to put it in [0, 6)
	my $f = $h - int($h);
	my @rgb_base;

	# Get RGB base values based on hue
	if ($h < 1) { @rgb_base = (1, $f, 0); }
	elsif ($h < 2) { @rgb_base = (1 - $f, 1, 0); }
	elsif ($h < 3) { @rgb_base = (0, 1, $f); }
	elsif ($h < 4) { @rgb_base = (0, 1 - $f, 1); }
	elsif ($h < 5) { @rgb_base = ($f, 0, 1); }
	else { @rgb_base = (1, 0, 1 - $f); }

	# Apply whiteness and blackness to compute final RGB values
	my $i = 1 - $whiteness - $blackness;
	my @rgb = map { _round(($whiteness + $i * $_) * 255) } @rgb_base;

	return @rgb;
	}

	sub _parse_angle {
	my ($angle) = @_;

	croak("Invalid color angle: $angle") unless $angle =~ /^(?:none\|[+-]?\d*\.?\d+(?:deg\|grad\|rad\|turn)?)$/;

	$angle = $angle =~ s/deg$// ? $angle
	: $angle =~ s/grad$// ? $angle * 360 / 400
	: $angle =~ s/rad$// ? $angle * 180 / 3.14159
	: $angle =~ s/turn$// ? $angle * 360
	: $angle;

	return _round($angle) % 360;

	}

	sub _round {
	my ($value) = @_;
	return int($value + 0.5);
	}

	1;

	__END__

	=head1 NAME

	Mail::SpamAssassin::HTML::Color - A class to parse and manipulate CSS color values

	=head1 SYNOPSIS

	use Mail::SpamAssassin::HTML::Color;

	my $color = Mail::SpamAssassin::HTML::Color->new('rgba(255, 0, 153, 0.5)');
	$color->blend([255, 255, 255]);
	my $distance = $color->distance([0, 0, 0]);
	print "$color"; # Outputs the color as a hex string

	=head1 DESCRIPTION

	This class provides methods to parse various CSS color formats, blend them with a background color, calculate the distance between two colors, and convert the color to a hex string.

	=head1 METHODS

	=head2 new($color)

	Creates a new color object from a CSS color string.

	=head2 blend($background)

	Blends the color with the given background color. Modifies the color in-place and returns the modified object.

	=head2 distance($other_color)

	Calculates the distance between the current color and another color using a brightness-weighted geometric formula.

	=head2 as_hex

	Returns the color as a hex string with a leading '#'.

	=head2 as_array

	Returns the color as an array of RGB values.

	=cut