termcol: avoid hexadecimal conversion for newyuv colours

[sheet.git] / Shiar_Sheet / Colour.pm

diff --git a/Shiar_Sheet/Colour.pm b/Shiar_Sheet/Colour.pm
index 303e37556c5825d2712652378e5a4f694023a203..e431cfed034bed92ed05b847ed1e0586201264f0 100644 (file)
--- a/Shiar_Sheet/Colour.pm
+++ b/Shiar_Sheet/Colour.pm
@@ -2,27 +2,68 @@ package Shiar_Sheet::Colour;
 
 use strict;
 use warnings;
-use List::Util 'min';
+use List::Util qw( min max );
 
-our $VERSION = '1.00';
+our $VERSION = '1.05';
 
 # ITU-R recommendation 601 luma co-efficients
 our $kr = .299;
 our $kb = .114;
 our $kg = 1 - $kb - $kr;
 
+my $PI = 2 * atan2 1, 0;
+
 sub new {
        my $class = shift;
        my @rgb = @_ >= 3 ? @_ : (map {hex} $_[0] =~ /(..)/g);
        bless \@rgb, $class;
 }
 
+sub newyuv {
+       # convert from YPbPr values -1..1
+       my $class = shift;
+       my ($y, $cb, $cr) = @_;
+
+       my @rgb = map { max(0, min(255, $_ * 255)) } (
+               $y                             + $cr,
+               $y - $cb * (1 - $kb) * $kb/$kg - $cr * $kr/$kg,
+               $y + $cb * (1 - $kb)           ,
+       );
+       bless \@rgb, $class;
+}
+
+sub newyuv8 {
+       # convert from YPbPr values 0..255 (or hex string)
+       my $class = shift;
+       my ($y, $cb, $cr) = @_ >= 3 ? @_ : (map {hex} $_[0] =~ /(..)/g);
+
+       $_ -= 128 for $cb, $cr;
+       $_ /= 255 for $y, $cb, $cr;
+
+       $class->newyuv($y, $cb, $cr);
+}
+
 sub luminance {
        # perceived brightness
        my ($r, $g, $b) = @{ $_[0] };
        return $r*$kr + $g*$kg + $b*$kb;
 }
 
+sub hue {
+       # colour shift (red = 0 .. 1)
+       my ($r, $g, $b) = @{ $_[0] };
+       my $hue = atan2 sqrt(3) * ($g - $b), $r*2 - $g - $b;
+       $hue /= $PI * 2;  # -.5 .. .5
+       $hue++ if $hue < 0;  # fp $hue %= 1
+       return $hue;
+}
+
+sub hsv {
+       my ($rgb) = @_;
+       my $v = max(@{$rgb});
+       return $rgb->hue, abs(min(@{$rgb}) - $v), $v;
+}
+
 sub rgb24 {
        my $str = '';
        $str .= sprintf '%X', min($_ / 17 + .5, 15) for @{ $_[0] };