1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
# You may distribute under the terms of either the GNU General Public License
# or the Artistic License (the same terms as Perl itself)
#
# (C) Paul Evans, 2009 -- leonerd@leonerd.org.uk
package Convert::Color::HSL;
use strict;
use warnings;
use base qw( Convert::Color::HueBased );
use constant COLOR_SPACE => 'hsl';
use Carp;
our $VERSION = '0.05';
=head1 NAME
C<Convert::Color::HSL> - a color value represented as hue/saturation/lightness
=head1 SYNOPSIS
Directly:
use Convert::Color::HSL;
my $red = Convert::Color::HSL->new( 0, 1, 0.5 );
# Can also parse strings
my $pink = Convert::Color::HSL->new( '0,1,0.8' );
Via L<Convert::Color>:
use Convert::Color;
my $cyan = Convert::Color->new( 'hsl:300,1,0.5' );
=head1 DESCRIPTION
Objects in this class represent a color in HSL space, as a set of three
floating-point values. Hue is stored as a value in degrees, in the range
0 to 360 (exclusive). Saturation and lightness are in the range 0 to 1.
=cut
=head1 CONSTRUCTOR
=cut
=head2 $color = Convert::Color::HSL->new( $hue, $saturation, $lightness )
Returns a new object to represent the set of values given. The hue should be
in the range 0 to 360 (exclusive), and saturation and lightness should be
between 0 and 1. Values outside of these ranges will be clamped.
=head2 $color = Convert::Color::HSL->new( $string )
Parses C<$string> for values, and construct a new object similar to the above
three-argument form. The string should be in the form
hue,saturation,lightnes
containing the three floating-point values in decimal notation.
=cut
sub new
{
my $class = shift;
my ( $h, $s, $l );
if( @_ == 1 ) {
local $_ = $_[0];
if( m/^(\d+(?:\.\d+)?),(\d+(?:\.\d+)?),(\d+(?:\.\d+)?)$/ ) {
( $h, $s, $l ) = ( $1, $2, $3 );
}
else {
croak "Unrecognised HSL string spec '$_'";
}
}
elsif( @_ == 3 ) {
( $h, $s, $l ) = @_;
}
else {
croak "usage: Convert::Color::HSL->new( SPEC ) or ->new( H, S, L )";
}
# Clamp
map { $_ < 0 and $_ = 0; $_ > 1 and $_ = 1 } ( $s, $l );
# Fit to range [0,360)
$h += 360 while $h < 0;
$h -= 360 while $h >= 360;
return bless [ $h, $s, $l ], $class;
}
=head1 METHODS
=cut
=head2 $h = $color->hue
=head2 $s = $color->saturation
=head2 $v = $color->lightness
Accessors for the three components of the color.
=cut
# Simple accessors
sub hue { shift->[0] }
sub saturation { shift->[1] }
sub lightness { shift->[2] }
=head2 ( $hue, $saturation, $lightness ) = $color->hsl
Returns the individual hue, saturation and lightness components of the color
value.
=cut
sub hsl
{
my $self = shift;
return @$self;
}
# Conversions
sub rgb
{
my $self = shift;
# See also
# http://en.wikipedia.org/wiki/HSV_color_space
my ( $h, $s, $l ) = $self->hsl;
my $q = $l < 0.5 ? $l * ( 1 + $s )
: $l + $s - ( $l * $s );
my $p = 2 * $l - $q;
# Modify the algorithm slightly, so we scale this up by 6
my $hk = $h / 60;
my $tr = $hk + 2;
my $tg = $hk;
my $tb = $hk - 2;
map {
$_ += 6 while $_ < 0;
$_ -= 6 while $_ > 6;
} ( $tr, $tg, $tb );
return map {
$_ < 1 ? $p + ( ( $q - $p ) * $_ ) :
$_ < 3 ? $q :
$_ < 4 ? $p + ( ( $q - $p ) * ( 4 - $_ ) ) :
$p
} ( $tr, $tg, $tb );
}
sub new_rgb
{
my $class = shift;
my ( $r, $g, $b ) = @_;
my ( $hue, $min, $max ) = $class->_hue_min_max( $r, $g, $b );
my $l = ( $max + $min ) / 2;
my $s = $min == $max ? 0 :
$l <= 1/2 ? ( $max - $min ) / ( 2 * $l ) :
( $max - $min ) / ( 2 - 2 * $l );
return $class->new( $hue, $s, $l );
}
# Keep perl happy; keep Britain tidy
1;
__END__
=head1 SEE ALSO
=over 4
=item *
L<Convert::Color> - color space conversions
=item *
L<Convert::Color::RGB> - a color value represented as red/green/blue
=back
=head1 AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
|
