---
name: "Ace::Graphics::Track"
section: "3pm"
platform: "linux"
package: "libace-perl"
version: "1.92-12+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Ace::Graphics::Track"
---

# Ace::Graphics::Track(3pm)

PNG graphics of Ace::Sequence::Feature objects

## NAME

Ace::Graphics::Track - PNG graphics of Ace::Sequence::Feature objects

## SYNOPSIS

```
  use Ace::Sequence;
  use Ace::Graphics::Panel;
  my $db     = Ace->connect(-host=>'brie2.cshl.org',-port=>2005) or die;
  my $cosmid = Ace::Sequence->new(-seq=>'Y16B4A',
                                  -db=>$db,-start=>-15000,-end=>15000) or die;
  my @transcripts = $cosmid->transcripts;
  my $panel = Ace::Graphics::Panel->new(
                                      -segment => $cosmid,
                                      -width  => 800
                                     );
  my $track = $panel->add_track('transcript'
                                -fillcolor =>  'wheat',
                                -fgcolor   =>  'black',
                                -bump      =>  +1,
                                -height    =>  10,
                                -label     =>  1);
  foreach (@transcripts) {
     $track->add_feature($_);
  }
  my $boxes = $panel->boxes;
  print $panel->png;
```

## DESCRIPTION

The Ace::Graphics::Track class is used by Ace::Graphics::Panel to lay out a set of sequence features using a uniform glyph type. You will ordinarily work with panels rather than directly with tracks.

## METHODS

This section describes the class and object methods for Ace::Graphics::Panel.

### CONSTRUCTORS

There is only one constructor, the **new()** method.  It is ordinarily called by Ace::Graphics::Panel, and not in end-developer code.

- $track = Ace::Graphics::Track-\>new($glyph\_name,$features,@options)

  The **new()** method creates a new track object from the provided glyph name and list of features.  The arguments are similar to those in Ace::Graphics::Panel-\>**new()**.

  If successful **new()** will return a new Ace::Graphics::Track. Otherwise, it will return undef.

  If the specified glyph name is not a valid one, **new()** will throw an exception.

### OBJECT METHODS

Once a track is created, the following methods can be invoked.

- $track-\>add\_feature($feature)

  This adds a new feature to the track.  The feature can either be a single object that implements the Bio::SeqFeatureI interface (such as an Ace::Sequence::Feature or Das::Segment::Feature), or can be an anonymous array containing a set of related features.  In the latter case, the track will attempt to keep the features in the same horizontal band and will not allow any other features to overlap.

- $track-\>add\_group($group)

  This behaves the same as **add\_feature()**, but requires that its argument be an array reference containing a list of grouped features.

- $track-\>draw($gd,$left,$top)

  Render the track on a previously-created GD::Image object.  The `$left` and `$top` arguments indicate the position at which to start rendering.

- $boxes = $track-\>boxes($left,$top)

  - @boxes = $track-\>boxes($left,$top)

  Return an array of array references indicating glyph coordinates for each of the render features.  `$left` and `$top` indicate the offset for the track on the image plane.  In a scalar context, this method returns an array reference of glyph coordinates.  In a list context, it returns the list itself.

  See Ace::Graphics::Panel-\>**boxes()** for the format of the result.

### ACCESSORS

The following accessor methods provide access to various attributes of the track object.  Called with no arguments, they each return the current value of the attribute.  Called with a single argument, they set the attribute and return its previous value.

Note that in most cases you must change attributes before the track's **layout()** method is called.

```
   Accessor Name      Description
   -------------      -----------
   scale()            Get/set the track scale, measured in pixels/bp
   lineheight()       Get/set the height of each glyph, pixels
   width()            Get/set the width of the track
   bump()             Get/set the bump direction
```

### INTERNAL METHODS

The following methods are used internally, but may be useful for those implementing new glyph types.

- $glyphs = $track-\>layout

  Layout the features, and return an anonymous array of Ace::Graphics::Glyph objects that have been created and correctly positioned.

  Because layout is an expensive operation, calling this method several times will return the previously-cached result, ignoring any changes to track attributes.

- $height = $track-\>height

  Invokes **layout()** and returns the height of the track.

- $glyphs = $track-\>glyphs

  Returns the glyph cache.  Returns undef before **layout()** and a reference to an array of glyphs after **layout()**.

- $factory = $track-\>make\_factory(@options)

  Given a set of options (argument/value pairs), returns a Ace::Graphics::GlyphFactory for use in creating the glyphs with the desired settings.

## BUGS

Please report them.

## SEE ALSO

Ace::Sequence,Ace::Sequence::Feature,Ace::Graphics::Panel, Ace::Graphics::GlyphFactory,Ace::Graphics::Glyph

## AUTHOR

Lincoln Stein \<lstein@cshl.org\>.

Copyright (c) 2001 Cold Spring Harbor Laboratory

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.  See DISCLAIMER.txt for disclaimers of warranty.