============
django-layar
============

Django generic view for making `Layar <http://layar.com>`_ endpoints.

Provides abstract class that responds to Layar API requests in the appropriate format.  By implementing two small functions it is possible to add a layer to the Layar augmented reality application for Android and iPhone.

django-layar is a project of Sunlight Labs (c) 2009.
Written by James Turk <jturk@sunlightfoundation.com>

Source: http://github.com/sunlightlabs/django-layar/

Requirements
============

python >= 2.4

django >= 1.0

Installation
============

To install run

    ``python setup.py install``

which will install the application into the site-packages directory.

Usage
=====

Layar Developer Key
--------------------

If you haven't already, it is necessary to `sign up with Layar <http://dev.layar.com>`_ to obtain an API key.

Set ``LAYAR_DEVELOPER_KEY='<YOUR_KEY>'`` in settings.py


Creating a ``LayarView`` subclass
---------------------------------

django-layar provides a class-based generic view at :class:`layar.LayarView`.  In order to provide your own layers
it is necessary to inherit from this view and implement two simple functions (per layer).

The required functions are :func:`get_LAYERNAME_queryset` and :func:`poi_from_LAYERNAME_item`.

It is possible to serve as many layers as you desire from a single Layar endpoint, just make sure that the name of your functions matches the name you provide when registering your layers with Layar.com

:func:`get_LAYERNAME_queryset` is passed a number of arguments (see :class:`layar.LayarView` for detail)
and should return a queryset of the objects for :class:`LayarView` to paginate and return.

:func:`poi_from_LAYERNAME_item` is called on each item being returned, and should convert items
into :class:`layar.POI` objects.

It is usually best to then create an instance of your derived class in your application's ``views.py``

Example::

    # views.py

    from django.contrib.gis.geos import Point
    from myapp.models import BusStop
    from layar import LayarView, POI

    class BusStopLayar(LayarView):

        # make sure to accept **kwargs
        def get_busstop_queryset(self, latitude, longitude, radius, **kwargs):
            return BusStop.objects.filter(location__distance_lt=(Point(longitude, latitude), radius))

        def poi_from_recoverygov_item(self, item):
            return POI(id=item.id, lat=item.location.y, lon=item.location.x, title=item.name,
                        line2=item.route_name, line3='Distance: %distance%')

    # create an instance of BusStopLayar
    busstop_layar = BusStopLayar()

In urls.py it is then necessary to map a URL directly to ``busstop_layar``::

    # urls.py

    from django.conf.urls.defaults import *

    urlpatterns = patterns('',
        url(r'^layar_endpoint/$', 'myapp.views.busstop_layar'),
    )

Additional Settings
-------------------

Your :class:`LayarView`-derived class can also set a number of options.  These options should be suitable for most purposes as Layar doesn't display more than 50 points, but are available should you for any reason need to change them.

``results_per_page``
    controls the number of results returned at once (default: 15)
``max_results``
    controls the maximum number of results across all pages (default: 50)
``verify_hash``
    set to False to disable hash verification (useful for testing, shouldn't be False in production)