Layout::Manager(3p)

NAME
Layout::Manager - 2D Layout Management

SYNOPSIS
Layout::Manager provides a simple interface for creating layout managers, or classes that size and position components within a container.

A few managers are provided for reference, but this module is primarily meant to serve as a base for outside implementations.

    use Layout::Manager;

    my $foo = Layout::Manager->new;
    $foo->do_layout($component);

USING A LAYOUT MANAGER
Layout::Manager relies on Graphics::Primitive::Container as a source for it's components.

Various implementations of Layout::Manager will require you do add components with slightly different second arguments, but the general case will be:

  $lm->add_component($comp, $constraints);

The contents of $constraints must be discerned by reading the documentation for the layout manager you are using.

The $comp argument must be a Graphics::Primitive::Component.

Layout manager works hand-in-hand with Graphics::Primitive, so you'll want to check out the lifecyle documented in Graphics::Primitive::Component. It will look something like this:

  $cont->add_component($foo, { some => metadata });
  $driver->prepare($cont);
  my $lm = new Layout::Manager::SomeImplementation;
  $lm->do_layout($cont);
  $driver->pack($cont);
  $driver->draw($cont);

When you are ready to lay out your container, you'll need to call the do_layout method with a single argument: the component in which you are laying things out. When do_layout returns all of the components should be resized and repositioned according to the rules of the Layout::Manager implementation.

  PREPARATION
Subsequent calls to do_layout will be ignored if the Container is prepared. The Container's "prepared" flag and the flags of all it's children are checked, so any modifications to any child component will cause the entire container (and any container children) to be laid out again.

WRITING A LAYOUT MANAGER
Layout::Manager provides all the methods necessary for your implementation, save the do_layout method. This method will be called when it is time to layout the components.

The add_component method takes two arguments: the component and a second, abritrary piece of data. If your layout manager is simple, like Compass, you may only require a simple variable like "NORTH". If you create something more complex the second argument may be a hashref or an object.

The value of the components method is an arrayref of hashrefs. The hashrefs have two keys:

component
    The component to be laid out.

args
    The argument provided to add_component.

TIPS
Layout manager implementations should honor the visible attribute of a component, as those components need to be ignored.

METHODS

  do_layout
Lays out this manager's components in the specified container.

AUTHOR
Cory Watson, "<gphat@cpan.org>"

SEE ALSO
perl(1), Graphics::Primitive

COPYRIGHT & LICENSE
Copyright 2008 - 2010 Cory G Watson

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.