view release on metacpan or  search on metacpan

lib/GD/Simple.pm  view on Meta::CPAN

Convert a Red/Green/Blue (RGB) value into a Hue/Saturation/Value (HSV)
triple. The hue, saturation and value are integers from 0 to 255.

=back

=cut

sub RGBtoHSV {
  my $self = shift;
  my ($r, $g ,$bl) = @_;
  my ($min,undef,$max) = sort {$a<=>$b} ($r,$g,$bl);
  return (0,0,0) unless $max > 0;

  my $v = $max;
  my $s = 255 * ($max - $min)/$max;
  my $h;
  my $range = $max - $min;

  if ($range == 0) { # all colors are equal, so monochrome
    return (0,0,$max);
  }

  if ($max == $r) {
    $h = 60 * ($g-$bl)/$range;
  }
  elsif ($max == $g) {
    $h = 60 * ($bl-$r)/$range + 120;
  }
  else {
    $h = 60 * ($r-$g)/$range + 240;
  }

  $h += 360 if $h < 0;
  $h = int($h*255/360 + 0.5);

  return ($h, $s, $v);
}

sub newGroup {
    my $self  = shift;
    return $self->GD::newGroup(@_);
}

1;

=head1 COLORS

This script will create an image showing all the symbolic colors.

 #!/usr/bin/perl

 use strict;
 use GD::Simple;

 my @color_names = GD::Simple->color_names;
 my $cols = int(sqrt(@color_names));
 my $rows = int(@color_names/$cols)+1;

 my $cell_width    = 100;
 my $cell_height   = 50;
 my $legend_height = 16;
 my $width       = $cols * $cell_width;
 my $height      = $rows * $cell_height;

 my $img = GD::Simple->new($width,$height);
 $img->font(gdSmallFont);

 for (my $c=0; $c<$cols; $c++) {
   for (my $r=0; $r<$rows; $r++) {
     my $color = $color_names[$c*$rows + $r] or next;
     my @topleft  = ($c*$cell_width,$r*$cell_height);
     my @botright = ($topleft[0]+$cell_width,$topleft[1]+$cell_height-$legend_height);
     $img->bgcolor($color);
     $img->fgcolor($color);
     $img->rectangle(@topleft,@botright);
     $img->moveTo($topleft[0]+2,$botright[1]+$legend_height-2);
     $img->fgcolor('black');
     $img->string($color);
   }
 }

 print $img->png;

=head1 AUTHOR

The GD::Simple module is copyright 2004, Lincoln D. Stein.  It is
distributed under the same terms as Perl itself.  See the "Artistic
License" in the Perl source code distribution for licensing terms.

The latest versions of GD.pm are available at https://github.com/lstein/Perl-GD

=head1 SEE ALSO

L<GD>,
L<GD::Polyline>,
L<GD::SVG>,
L<Image::Magick>

=cut