From f4d656e15874284607d875bfa04fd096a2ebf356 Mon Sep 17 00:00:00 2001
From: Tobi Oetiker <tobi@oetiker.ch>
Date: Tue, 4 Jul 2006 07:19:52 +0000
Subject: forgot to add when incoorperating the loss_background patch

---
 lib/Smokeping/Colorspace.pm | 148 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 lib/Smokeping/Colorspace.pm

(limited to 'lib')

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;
+
-- 
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