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| -rw-r--r-- | lib/Smokeping/Colorspace.pm | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/lib/Smokeping/Colorspace.pm b/lib/Smokeping/Colorspace.pm new file mode 100644 index 0000000..9f58357 --- /dev/null +++ b/lib/Smokeping/Colorspace.pm @@ -0,0 +1,148 @@ +# -*- perl -*- + +package Smokeping::Colorspace; + +=head1 OVERVIEW + +This module provides simple colorspace conversion methods, primarily allowing +conversion from RGB (red, green, blue) to and from HSL (hue, saturation, luminosity). + +=head1 COPYRIGHT + +Copyright 2006 by Grahame Bowland. + +=head1 LICENSE + +This program is free software; you can redistribute it +and/or modify it under the terms of the GNU General Public +License as published by the Free Software Foundation; either +version 2 of the License, or (at your option) any later +version. + +This program is distributed in the hope that it will be +useful, but WITHOUT ANY WARRANTY; without even the implied +warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR +PURPOSE. See the GNU General Public License for more +details. + +You should have received a copy of the GNU General Public +License along with this program; if not, write to the Free +Software Foundation, Inc., 675 Mass Ave, Cambridge, MA +02139, USA. + +=head1 AUTHOR + +Grahame Bowland <grahame.bowland@uwa.edu.au> + +=cut + +sub web_to_rgb { + my $web = shift; + $web =~ s/^#//; + my @rgb = (hex(substr($web, 0, 2)) / 255, + hex(substr($web, 2, 2)) / 255, + hex(substr($web, 4, 2)) / 255) ; + return @rgb; +} + +sub rgb_to_web { + my @rgb = @_; + return sprintf("#%.2x%.2x%.2x", 255 * $rgb[0], 255 * $rgb[1], 255 * $rgb[2]); +} + +sub min_max_indexes { + my $idx = 0; + my ($min_idx, $min, $max_idx, $max); + my @l = @_; + + foreach my $i (@l) { + if (not defined($min) or ($i < $min)) { + $min = $i; + $min_idx = $idx; + } + if (not defined($max) or ($i > $max)) { + $max = $i; + $max_idx = $idx; + } + $idx++; + } + return ($min_idx, $min, $max_idx, $max); +} + +# source for conversion algorithm is: +# http://www.easyrgb.com/math.php?MATH=M18#text18 +sub rgb_to_hsl { + my @rgb = @_; + my ($h, $l, $s); + + my ($min_idx, $min, $max_idx, $max) = min_max_indexes(@rgb); + my $delta_max = $max - $min; + $l = ($max + $min) / 2; + if ($delta_max == 0) { + my $h = 0; + my $s = 0; + } else { + if ($l < 0.5) { + $s = $delta_max / ($max + $min); + } else { + $s = $delta_max / (2 - $max - $min); + } + my $delta_r = ((($max - $rgb[0]) / 6) + ($max / 2)) / $delta_max; + my $delta_g = ((($max - $rgb[1]) / 6) + ($max / 2)) / $delta_max; + my $delta_b = ((($max - $rgb[2]) / 6) + ($max / 2)) / $delta_max; + if ($max_idx == 0) { + $h = $delta_b - $delta_g; + } elsif ($max_idx == 1) { + $h = (1/3) + $delta_r - $delta_b; + } else { + $h = (2/3) + $delta_g - $delta_r; + } + if ($h < 0) { + $h += 1; + } elsif ($h > 1) { + $h -= 1; + } + } + return ($h, $s, $l); +} + +sub hue_to_rgb { + my ($v1, $v2, $vh) = @_; + if ($vh < 0) { + $vh += 1; + } elsif ($vh > 1) { + $vh -= 1; + } + if ($vh * 6 < 1) { + return $v1 + ($v2 - $v1) * 6 * $vh; + } elsif ($vh * 2 < 1) { + return $v2; + } elsif ($vh * 3 < 2) { + return $v1 + ($v2 - $v1) * ((2/3) - $vh) * 6; + } else { + return $v1; + } +} + +sub hsl_to_rgb { + my ($h, $s, $l) = @_; + my ($r, $g, $b); + if ($s == 0) { + $r = $g = $b = $l; + } else { + my $ls; + if ($l < 0.5) { + $ls = $l * (1 + $s); + } else { + $ls = ($l + $s) - ($s * $l); + } + $l = 2 * $l - $ls; + $r = hue_to_rgb($l, $ls, $h + 1/3); + $g = hue_to_rgb($l, $ls, $h); + $b = hue_to_rgb($l, $ls, $h - (1/3)); + } + return ($r, $g, $b); +} + +1; + |