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Zend Framework 2 Documentation (Manual)

File: /_sources/modules/zend.captcha.adapters.txt

.. _zend.captcha.adapters:

CAPTCHA Adapters
================

The following adapters are shipped with Zend Framework by default.

.. _zend.captcha.adapters.abstractword:

Zend\\Captcha\\AbstractWord
---------------------------

``Zend\Captcha\AbstractWord`` is an abstract adapter that serves as the base class for most other *CAPTCHA* adapters. It
provides mutators for specifying word length, session *TTL* and the session container object to use.
``Zend\Captcha\AbstractWord`` also encapsulates validation logic.

By default, the word length is 8 characters, the session timeout is 5 minutes, and ``Zend\Session\Container`` is
used for persistence (using the namespace "``Zend\Form\Captcha\<captcha ID>``").

In addition to the methods required by the ``Zend\Captcha\AdapterInterface`` interface, ``Zend\Captcha\AbstractWord``
exposes the following methods:

- ``setWordLen($length)`` and ``getWordLen()`` allow you to specify the length of the generated "word" in
  characters, and to retrieve the current value.

- ``setTimeout($ttl)`` and ``getTimeout()`` allow you to specify the time-to-live of the session token, and to
  retrieve the current value. ``$ttl`` should be specified in seconds.

- ``setUseNumbers($numbers)`` and ``getUseNumbers()`` allow you to specify if numbers will be considered as
  possible characters for the random work or only letters would be used.

- ``setSessionClass($class)`` and ``getSessionClass()`` allow you to specify an alternate
  ``Zend\Session\Container`` implementation to use to persist the *CAPTCHA* token and to retrieve the current
  value.

- ``getId()`` allows you to retrieve the current token identifier.

- ``getWord()`` allows you to retrieve the generated word to use with the *CAPTCHA*. It will generate the word for
  you if none has been generated yet.

- ``setSession(Zend\Session\Container $session)`` allows you to specify a session object to use for persisting the
  *CAPTCHA* token. ``getSession()`` allows you to retrieve the current session object.

All word *CAPTCHA*\ s allow you to pass an array of options or ``Traversable`` object to the constructor, or,
alternately, pass them to ``setOptions()``. By default, the **wordLen**, **timeout**, and **sessionClass** keys may
all be used. Each concrete implementation may define additional keys or utilize the options in other ways.

.. note::

   ``Zend\Captcha\AbstractWord`` is an abstract class and may not be instantiated directly.

.. _zend.captcha.adapters.dumb:

Zend\\Captcha\\Dumb
-------------------

The ``Zend\Captcha\Dumb`` adapter is mostly self-descriptive. It provides a random string that must be typed in
reverse to validate. As such, it's not a good *CAPTCHA* solution and should only be used for testing. It extends
``Zend\Captcha\AbstractWord``.

.. _zend.captcha.adapters.figlet:

Zend\\Captcha\\Figlet
---------------------

The ``Zend\Captcha\Figlet`` adapter utilizes :ref:`Zend\\Text\\Figlet <zend.text.figlet>` to present a figlet to
the user.

Options passed to the constructor will also be passed to the :ref:`Zend\\Text\\Figlet <zend.text.figlet>` object.
See the :ref:`Zend\\Text\\Figlet <zend.text.figlet>` documentation for details on what configuration options are
available.

.. _zend.captcha.adapters.image:

Zend\\Captcha\\Image
--------------------

The ``Zend\Captcha\Image`` adapter takes the generated word and renders it as an image, performing various skewing
permutations to make it difficult to automatically decipher. It requires the `GD extension`_ compiled with TrueType
or Freetype support. Currently, the ``Zend\Captcha\Image`` adapter can only generate *PNG* images.

``Zend\Captcha\Image`` extends ``Zend\Captcha\AbstractWord``, and additionally exposes the following methods:

- ``setExpiration($expiration)`` and ``getExpiration()`` allow you to specify a maximum lifetime the *CAPTCHA*
  image may reside on the filesystem. This is typically a longer than the session lifetime. Garbage collection is
  run periodically each time the *CAPTCHA* object is invoked, deleting all images that have expired. Expiration
  values should be specified in seconds.

- ``setGcFreq($gcFreq)`` and ``getGcFreg()`` allow you to specify how frequently garbage collection should run.
  Garbage collection will run every ``1/$gcFreq`` calls. The default is 100.

- ``setFont($font)`` and ``getFont()`` allow you to specify the font you will use. ``$font`` should be a fully
  qualified path to the font file. This value is required; the *CAPTCHA* will throw an exception during generation
  if the font file has not been specified.

- ``setFontSize($fsize)`` and ``getFontSize()`` allow you to specify the font size in pixels for generating the
  *CAPTCHA*. The default is 24px.

- ``setHeight($height)`` and ``getHeight()`` allow you to specify the height in pixels of the generated *CAPTCHA*
  image. The default is 50px.

- ``setWidth($width)`` and ``getWidth()`` allow you to specify the width in pixels of the generated *CAPTCHA*
  image. The default is 200px.

- ``setImgDir($imgDir)`` and ``getImgDir()`` allow you to specify the directory for storing *CAPTCHA* images. The
  default is "``./images/captcha/``", relative to the bootstrap script.

- ``setImgUrl($imgUrl)`` and ``getImgUrl()`` allow you to specify the relative path to a *CAPTCHA* image to use for
  *HTML* markup. The default is "``/images/captcha/``".

- ``setSuffix($suffix)`` and ``getSuffix()`` allow you to specify the filename suffix for the *CAPTCHA* image. The
  default is "``.png``". Note: changing this value will not change the type of the generated image.

- ``setDotNoiseLevel($level)`` and ``getDotNoiseLevel()``, along with ``setLineNoiseLevel($level)`` and
  ``getLineNoiseLevel()``, allow you to control how much "noise" in the form of random dots and lines the image
  would contain. Each unit of ``$level`` produces one random dot or line. The default is 100 dots and 5 lines. The
  noise is added twice - before and after the image distortion transformation.

All of the above options may be passed to the constructor by simply removing the 'set' method prefix and casting
the initial letter to lowercase: "suffix", "height", "imgUrl", etc.

.. _zend.captcha.adapters.recaptcha:

Zend\\Captcha\\ReCaptcha
------------------------

The ``Zend\Captcha\ReCaptcha`` adapter uses :ref:`Zend\\Service\\ReCaptcha\\ReCaptcha <zendservice.recaptcha>` to
generate and validate *CAPTCHA*\ s. It exposes the following methods:

- ``setPrivKey($key)`` and ``getPrivKey()`` allow you to specify the private key to use for the ReCaptcha service.
  This must be specified during construction, although it may be overridden at any point.

- ``setPubKey($key)`` and ``getPubKey()`` allow you to specify the public key to use with the ReCaptcha service.
  This must be specified during construction, although it may be overridden at any point.

- ``setService(ZendService\ReCaptcha\ReCaptcha $service)`` and ``getService()`` allow you to set and get the
  ReCaptcha service object.



.. _`GD extension`: http://php.net/gd