<?php

/**

 * Zend Framework

 *

 * LICENSE

 *

 * This source file is subject to the new BSD license that is bundled

 * with this package in the file LICENSE.txt.

 * It is also available through the world-wide-web at this URL:

 * http://framework.zend.com/license/new-bsd

 * If you did not receive a copy of the license and are unable to

 * obtain it through the world-wide-web, please send an email

 * to license@zend.com so we can send you a copy immediately.

 *

 * @category   Zend

 * @package    Zend_Pdf

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 * @version    $Id: Image.php 20096 2010-01-06 02:05:09Z bkarwin $

 */

/** Internally used classes */

require_once 'Zend/Pdf/Element/Object.php';

require_once 'Zend/Pdf/Element/Dictionary.php';

require_once 'Zend/Pdf/Element/Name.php';

require_once 'Zend/Pdf/Element/Numeric.php';

/** Zend_Pdf_Resource */

require_once 'Zend/Pdf/Resource.php';

/**

 * Graphics State.

 *

 * While some parameters in the graphics state can be set with individual operators,

 * as shown in Table 4.7, others cannot. The latter can only be set with the generic

 * graphics state operator gs (PDF 1.2).

 *

 * @package    Zend_Pdf

 * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_Pdf_Resource_GraphicsState extends Zend_Pdf_Resource

{

    /**

     * Object constructor.

     *

     * @param Zend_Pdf_Element_Object $extGStateObject

     * @throws Zend_Pdf_Exception

     */

    public function __construct(Zend_Pdf_Element_Object $extGStateObject = null)

    {

        if ($extGStateObject == null) {

            // Create new Graphics State object

            require_once 'Zend/Pdf/ElementFactory.php';

            $factory = Zend_Pdf_ElementFactory::createFactory(1);

            $gsDictionary = new Zend_Pdf_Element_Dictionary();

            $gsDictionary->Type = new Zend_Pdf_Element_Name('ExtGState');

            $extGStateObject = $factory->newObject($gsDictionary);

        }

        if ($extGStateObject->getType() != Zend_Pdf_Element::TYPE_DICTIONARY) {

            require_once 'Zend/Pdf/Exception.php';

            throw new Zend_Pdf_Exception('Graphics state PDF object must be a dictionary');

        }

        parent::__construct($gsDictionary);

    }

    /**

     * Set the transparancy

     *

     * $alpha == 0  - transparent

     * $alpha == 1  - opaque

     *

     * Transparency modes, supported by PDF:

     * Normal (default), Multiply, Screen, Overlay, Darken, Lighten, ColorDodge, ColorBurn, HardLight,

     * SoftLight, Difference, Exclusion

     *

     * @param float $alpha

     * @param string $mode

     * @throws Zend_Pdf_Exception

     * @return Zend_Pdf_Canvas_Interface

     */

    public function setAlpha($alpha, $mode = 'Normal')

    {

        if (!in_array($mode, array('Normal', 'Multiply', 'Screen', 'Overlay', 'Darken', 'Lighten', 'ColorDodge',

                                   'ColorBurn', 'HardLight', 'SoftLight', 'Difference', 'Exclusion'))) {

            require_once 'Zend/Pdf/Exception.php';

            throw new Zend_Pdf_Exception('Unsupported transparency mode.');

        }

        if (!is_numeric($alpha)  ||  $alpha < 0  ||  $alpha > 1) {

            require_once 'Zend/Pdf/Exception.php';

            throw new Zend_Pdf_Exception('Alpha value must be numeric between 0 (transparent) and 1 (opaque).');

        }

        $this->_resource->BM   = new Zend_Pdf_Element_Name($mode);

        $this->_resource->CA   = new Zend_Pdf_Element_Numeric($alpha);

        $this->_resource->ca   = new Zend_Pdf_Element_Numeric($alpha);

    }

    /** @todo add other Graphics State features support */

}