Bio::Graphics::Glyph::broken_line - The "broken line" glyph

  See L<Bio::Graphics::Panel> and L<Bio::Graphics::Glyph>.

  Option      Description                  Default
  ------      -----------                  -------

  -draw_beak Whether to draw the 'break'.       1

  -shear    Vertical distance between     	5
			the main line and the segment

  -shear_up Whether to shift the segment 	1
				up or down (1 or 0)

  -break 	Width of the break in the line 	8

  -extend  	Whether to extend the line or   1 
			to keep the length fixed (1 or 0) 

  -size  	Total length of the line and   30 
			the break, if extend is 0

  -omit_left	Whether to omit the left	0
			half of the main line

  -omit_right	Whether to omit the right	0
			half of the main line

package Bio::Graphics::Glyph::broken_line;

use strict;
use base qw(Bio::Graphics::Glyph::generic);

sub my_description {
    return <<END;
This glyph draws a straight line whose segment is shifted ("sheared")
up or down. There can be an optional "break" (two diagonal lines
passing between the main line and its segment).
Either the left or the right side of the main line can be absent.
The line can be of fixed size or extend to take up all available space.
END
}
sub my_options {
    return {
	draw_break => [
	    'boolean',
	    1,
	    'If true, draw the "break."'],
	shear => [
	    'integer',
	    5,
	    'Vertical distance between the main line and the segment.'],
        shear_up => [
	    'boolean',
	    1,
	    'Whether to shift the segment up (true) or down (false).'],
	break => [
	    'integer',
	    8,
	    'Width of the break in the line.'],
        extend => [
	    'boolean',
	    1,
	    'Whether to extend the line or to keep the length fixed.'],
	size => [
	    'integer',
	    30,
	    'Total length of the line and its break, if extend is false.'],
	omit_left => [
	    'boolean',
	    undef,
	    'If true, omit the left half of the main line.'],
	omit_right => [
	    'boolean',
	    undef,
	    'If true, omit the right half of the main line.'],
    }
}

sub default_draw_beak
{
  return 1;  
}

sub default_shear
{
  return 5;  
}

sub default_shear_up
{
  return 1;  
}

sub default_break
{
  return 8;  
}

sub default_extend
{
  return 1;  
}

sub default_size
{
  return 30;  
}

sub default_omit_left
{
  return 0;  
}

sub default_omit_right
{
  return 0;  
}

sub draw_component {
  my $self = shift;
  my $gd = shift;
  my ($x1,$y1,$x2,$y2) = $self->calculate_boundaries(@_);
  
  my $fg = $self->fgcolor;
  my $bg = $self->bgcolor;
  
  my $shear = defined $self->option('shear') ? $self->option('shear') : $self->default_shear();
  my $shear_up = defined $self->option('shear_up') ? $self->option('shear_up') : $self->default_shear_up();
  my $break = defined $self->option('break') ? $self->option('break') : $self->default_break();
  my $draw_beak = defined $self->option('draw_beak') ? $self->option('draw_beak') : $self->default_draw_beak();
  my $extend= defined $self->option('extend') ? $self->option('extend') : $self->default_extend();
  my $size = defined $self->option('size') ? $self->option('size') : $self->default_size();
  my $omit_left = defined $self->option('omit_left') ? $self->option('omit_left') : $self->default_omit_left();
  my $omit_right = defined $self->option('omit_right') ? $self->option('omit_right') : $self->default_omit_right();

  my $midY = ($y1+$y2)/2;
  
  if ($x2-$x1 < $size)
  {
    $gd->line($x1, $midY, $x2, $midY, $bg);
    return;
  }
  
  my $midX = ($x1+$x2)/2;
  
  my $break_start = $midX - $break/2;
  my $break_end = $midX + $break/2;
  
  my ($x11, $x12, $x21, $x22);
  $x12 = $break_start;
  $x21 = $break_end;

  if ($omit_left)
  {
    $break_start = $x1;
    $break_end = $x1+$break;
    $x21 = $break_end;
    $x22 = ($extend ? $x2 : $x21 + $size - $break);
  }
  elsif ($omit_right)
  {
    $x11 = $x1;
    $x12 = ($extend ? $x2 - $break : $x11 + $size - $break);
    $break_end = $x12+$break;
    $break_start = $x12;
  }
  else
  {
    if ($extend)
    {
      $x11 = $x1;
      $x22 = $x2;
    }
    else
    {
      $x11 = $break_start - ($size - $break) / 2;
      $x22 = $break_end + ($size - $break) / 2;
    }
  }
  
  unless ($omit_left)
  {
    $gd->line($x11, $midY, $x12, $midY, $bg);
  }
  
  my $shear_y = ($shear_up ? $midY - $shear : $midY + $shear);
  $gd->line($break_start, $shear_y, $break_end, $shear_y, $fg);
  if ($draw_beak)
  {
    $midX = ($break_start + $break_end) / 2;
    
    my $beak_y1 = $shear_up ? $midY + $shear/2 : $midY - $shear/2;
    my $beak_y2 = $shear_up ? $midY - $shear/2 : $midY + $shear/2;
    
    $gd->line($midX, $beak_y1, $midX-$shear, $beak_y2, $fg);  
    $gd->line($midX, $beak_y1, $midX+$shear, $beak_y2, $fg);  
  }
  
  unless ($omit_right)
  {
    $gd->line($x21, $midY, $x22, $midY, $bg);
  }
  
}

1;

__END__