/src/Joomla/Image/Image.php

<?php
/**
 * Part of the Joomla Framework Image Package
 *
 * @copyright  Copyright (C) 2005 - 2013 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE
 */

namespace Joomla\Image;

use Psr\Log\NullLogger;
use Psr\Log\LoggerInterface;
use Psr\Log\LoggerAwareInterface;

/**
 * Class to manipulate an image.
 *
 * @since  1.0
 */
class Image implements LoggerAwareInterface
{
	/**
	 * @const  integer
	 * @since  1.0
	 */
	const SCALE_FILL = 1;

	/**
	 * @const  integer
	 * @since  1.0
	 */
	const SCALE_INSIDE = 2;

	/**
	 * @const  integer
	 * @since  1.0
	 */
	const SCALE_OUTSIDE = 3;

	/**
	 * @const  integer
	 * @since  1.0
	 */
	const CROP = 4;

	/**
	 * @const  integer
	 * @since  1.0
	 */
	const CROP_RESIZE = 5;

	/**
	 * @const  integer
	 * @since  1.0
	 */
	const SCALE_FIT = 6;

	/**
	 * @var    resource  The image resource handle.
	 * @since  1.0
	 */
	protected $handle;

	/**
	 * @var    string  The source image path.
	 * @since  1.0
	 */
	protected $path = null;

	/**
	 * @var    array  Whether or not different image formats are supported.
	 * @since  1.0
	 */
	protected static $formats = array();

	/**
	 * @var    LoggerInterface  Logger object
	 * @since  1.0
	 */
	protected $logger = null;

	/**
	 * Class constructor.
	 *
	 * @param   mixed  $source  Either a file path for a source image or a GD resource handler for an image.
	 *
	 * @since   1.0
	 * @throws  \RuntimeException
	 */
	public function __construct($source = null)
	{
		// Verify that GD support for PHP is available.
		if (!extension_loaded('gd'))
		{
			// @codeCoverageIgnoreStart
			throw new \RuntimeException('The GD extension for PHP is not available.');

			// @codeCoverageIgnoreEnd
		}

		// Determine which image types are supported by GD, but only once.
		if (!isset(self::$formats[IMAGETYPE_JPEG]))
		{
			$info = gd_info();
			self::$formats[IMAGETYPE_JPEG] = ($info['JPEG Support']) ? true : false;
			self::$formats[IMAGETYPE_PNG] = ($info['PNG Support']) ? true : false;
			self::$formats[IMAGETYPE_GIF] = ($info['GIF Read Support']) ? true : false;
		}

		// If the source input is a resource, set it as the image handle.
		if (is_resource($source) && (get_resource_type($source) == 'gd'))
		{
			$this->handle = &$source;
		}
		elseif (!empty($source) && is_string($source))
		{
			// If the source input is not empty, assume it is a path and populate the image handle.
			$this->loadFile($source);
		}
	}

	/**
	 * Get the logger.
	 *
	 * @return  LoggerInterface
	 *
	 * @since   1.0
	 */
	public function getLogger()
	{
		// If a logger hasn't been set, use NullLogger
		if (! ($this->logger instanceof LoggerInterface))
		{
			$this->logger = new NullLogger;
		}

		return $this->logger;
	}

	/**
	 * Sets a logger instance on the object
	 *
	 * @param   LoggerInterface  $logger  A PSR-3 compliant logger.
	 *
	 * @return  Image  This object for message chaining.
	 *
	 * @since   1.0
	 */
	public function setLogger(LoggerInterface $logger)
	{
		$this->logger = $logger;

		return $this;
	}

	/**
	 * Method to return a properties object for an image given a filesystem path.  The
	 * result object has values for image width, height, type, attributes, mime type, bits,
	 * and channels.
	 *
	 * @param   string  $path  The filesystem path to the image for which to get properties.
	 *
	 * @return  \stdClass
	 *
	 * @since   1.0
	 * @throws  \InvalidArgumentException
	 * @throws  \RuntimeException
	 */
	public static function getImageFileProperties($path)
	{
		// Make sure the file exists.
		if (!file_exists($path))
		{
			throw new \InvalidArgumentException('The image file does not exist.');
		}

		// Get the image file information.
		$info = getimagesize($path);

		if (!$info)
		{
			// @codeCoverageIgnoreStart
			throw new \RuntimeException('Unable to get properties for the image.');

			// @codeCoverageIgnoreEnd
		}

		// Build the response object.
		$properties = (object) array(
			'width' => $info[0],
			'height' => $info[1],
			'type' => $info[2],
			'attributes' => $info[3],
			'bits' => isset($info['bits']) ? $info['bits'] : null,
			'channels' => isset($info['channels']) ? $info['channels'] : null,
			'mime' => $info['mime']
		);

		return $properties;
	}

	/**
	 * Method to generate thumbnails from the current image. It allows
	 * creation by resizing or cropping the original image.
	 *
	 * @param   mixed    $thumbSizes      String or array of strings. Example: $thumbSizes = array('150x75','250x150');
	 * @param   integer  $creationMethod  1-3 resize $scaleMethod | 4 create croppping | 5 resize then crop
	 *
	 * @return  array
	 *
	 * @since   1.0
	 * @throws  \LogicException
	 * @throws  \InvalidArgumentException
	 */
	public function generateThumbs($thumbSizes, $creationMethod = self::SCALE_INSIDE)
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		// Accept a single thumbsize string as parameter
		if (!is_array($thumbSizes))
		{
			$thumbSizes = array($thumbSizes);
		}

		// Process thumbs
		$generated = array();

		if (!empty($thumbSizes))
		{
			foreach ($thumbSizes as $thumbSize)
			{
				// Desired thumbnail size
				$size = explode('x', strtolower($thumbSize));

				if (count($size) != 2)
				{
					throw new \InvalidArgumentException('Invalid thumb size received: ' . $thumbSize);
				}

				$thumbWidth  = $size[0];
				$thumbHeight = $size[1];

				switch ($creationMethod)
				{
					// Case for self::CROP
					case 4:
						$thumb = $this->crop($thumbWidth, $thumbHeight, null, null, true);
						break;

					// Case for self::CROP_RESIZE
					case 5:
						$thumb = $this->cropResize($thumbWidth, $thumbHeight, true);
						break;

					default:
						$thumb = $this->resize($thumbWidth, $thumbHeight, true, $creationMethod);
						break;
				}

				// Store the thumb in the results array
				$generated[] = $thumb;
			}
		}

		return $generated;
	}

	/**
	 * Method to create thumbnails from the current image and save them to disk. It allows creation by resizing
	 * or croppping the original image.
	 *
	 * @param   mixed    $thumbSizes      string or array of strings. Example: $thumbSizes = array('150x75','250x150');
	 * @param   integer  $creationMethod  1-3 resize $scaleMethod | 4 create croppping
	 * @param   string   $thumbsFolder    destination thumbs folder. null generates a thumbs folder in the image folder
	 *
	 * @return  array
	 *
	 * @since   1.0
	 * @throws  \LogicException
	 * @throws  \InvalidArgumentException
	 */
	public function createThumbs($thumbSizes, $creationMethod = self::SCALE_INSIDE, $thumbsFolder = null)
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		// No thumbFolder set -> we will create a thumbs folder in the current image folder
		if (is_null($thumbsFolder))
		{
			$thumbsFolder = dirname($this->getPath()) . '/thumbs';
		}

		// Check destination
		if (!is_dir($thumbsFolder) && (!is_dir(dirname($thumbsFolder)) || !@mkdir($thumbsFolder)))
		{
			throw new \InvalidArgumentException('Folder does not exist and cannot be created: ' . $thumbsFolder);
		}

		// Process thumbs
		$thumbsCreated = array();

		if ($thumbs = $this->generateThumbs($thumbSizes, $creationMethod))
		{
			// Parent image properties
			$imgProperties = self::getImageFileProperties($this->getPath());

			foreach ($thumbs as $thumb)
			{
				// Get thumb properties
				$thumbWidth     = $thumb->getWidth();
				$thumbHeight    = $thumb->getHeight();

				// Generate thumb name
				$filename       = pathinfo($this->getPath(), PATHINFO_FILENAME);
				$fileExtension  = pathinfo($this->getPath(), PATHINFO_EXTENSION);
				$thumbFileName  = $filename . '_' . $thumbWidth . 'x' . $thumbHeight . '.' . $fileExtension;

				// Save thumb file to disk
				$thumbFileName = $thumbsFolder . '/' . $thumbFileName;

				if ($thumb->toFile($thumbFileName, $imgProperties->type))
				{
					// Return Image object with thumb path to ease further manipulation
					$thumb->path = $thumbFileName;
					$thumbsCreated[] = $thumb;
				}
			}
		}

		return $thumbsCreated;
	}

	/**
	 * Method to crop the current image.
	 *
	 * @param   mixed    $width      The width of the image section to crop in pixels or a percentage.
	 * @param   mixed    $height     The height of the image section to crop in pixels or a percentage.
	 * @param   integer  $left       The number of pixels from the left to start cropping.
	 * @param   integer  $top        The number of pixels from the top to start cropping.
	 * @param   boolean  $createNew  If true the current image will be cloned, cropped and returned; else
	 *                               the current image will be cropped and returned.
	 *
	 * @return  Image
	 *
	 * @since   1.0
	 * @throws  \LogicException
	 */
	public function crop($width, $height, $left = null, $top = null, $createNew = true)
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		// Sanitize width.
		$width = $this->sanitizeWidth($width, $height);

		// Sanitize height.
		$height = $this->sanitizeHeight($height, $width);

		// Autocrop offsets
		if (is_null($left))
		{
			$left = round(($this->getWidth() - $width) / 2);
		}

		if (is_null($top))
		{
			$top = round(($this->getHeight() - $height) / 2);
		}

		// Sanitize left.
		$left = $this->sanitizeOffset($left);

		// Sanitize top.
		$top = $this->sanitizeOffset($top);

		// Create the new truecolor image handle.
		$handle = imagecreatetruecolor($width, $height);

		// Allow transparency for the new image handle.
		imagealphablending($handle, false);
		imagesavealpha($handle, true);

		if ($this->isTransparent())
		{
			// Get the transparent color values for the current image.
			$rgba = imageColorsForIndex($this->handle, imagecolortransparent($this->handle));
			$color = imageColorAllocate($this->handle, $rgba['red'], $rgba['green'], $rgba['blue']);

			// Set the transparent color values for the new image.
			imagecolortransparent($handle, $color);
			imagefill($handle, 0, 0, $color);

			imagecopyresized($handle, $this->handle, 0, 0, $left, $top, $width, $height, $width, $height);
		}
		else
		{
			imagecopyresampled($handle, $this->handle, 0, 0, $left, $top, $width, $height, $width, $height);
		}

		// If we are cropping to a new image, create a new Image object.
		if ($createNew)
		{
			// @codeCoverageIgnoreStart
			$new = new Image($handle);

			return $new;

			// @codeCoverageIgnoreEnd
		}
		else
		// Swap out the current handle for the new image handle.
		{
			// Free the memory from the current handle
			$this->destroy();

			$this->handle = $handle;

			return $this;
		}
	}

	/**
	 * Method to apply a filter to the image by type.  Two examples are: grayscale and sketchy.
	 *
	 * @param   string  $type     The name of the image filter to apply.
	 * @param   array   $options  An array of options for the filter.
	 *
	 * @return  Image
	 *
	 * @since   1.0
	 * @see     Joomla\Image\Filter
	 * @throws  \LogicException
	 */
	public function filter($type, array $options = array())
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		// Get the image filter instance.
		$filter = $this->getFilterInstance($type);

		// Execute the image filter.
		$filter->execute($options);

		return $this;
	}

	/**
	 * Method to get the height of the image in pixels.
	 *
	 * @return  integer
	 *
	 * @since   1.0
	 * @throws  \LogicException
	 */
	public function getHeight()
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		return imagesy($this->handle);
	}

	/**
	 * Method to get the width of the image in pixels.
	 *
	 * @return  integer
	 *
	 * @since   1.0
	 * @throws  \LogicException
	 */
	public function getWidth()
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		return imagesx($this->handle);
	}

	/**
	 * Method to return the path
	 *
	 * @return	string
	 *
	 * @since	1.0
	 */
	public function getPath()
	{
		return $this->path;
	}

	/**
	 * Method to determine whether or not an image has been loaded into the object.
	 *
	 * @return  boolean
	 *
	 * @since   1.0
	 */
	public function isLoaded()
	{
		// Make sure the resource handle is valid.
		if (!is_resource($this->handle) || (get_resource_type($this->handle) != 'gd'))
		{
			return false;
		}

		return true;
	}

	/**
	 * Method to determine whether or not the image has transparency.
	 *
	 * @return  bool
	 *
	 * @since   1.0
	 * @throws  \LogicException
	 */
	public function isTransparent()
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		return (imagecolortransparent($this->handle) >= 0);
	}

	/**
	 * Method to load a file into the Image object as the resource.
	 *
	 * @param   string  $path  The filesystem path to load as an image.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 * @throws  \InvalidArgumentException
	 * @throws  \RuntimeException
	 */
	public function loadFile($path)
	{
		// Destroy the current image handle if it exists
		$this->destroy();

		// Make sure the file exists.
		if (!file_exists($path))
		{
			throw new \InvalidArgumentException('The image file does not exist.');
		}

		// Get the image properties.
		$properties = self::getImageFileProperties($path);

		// Attempt to load the image based on the MIME-Type
		switch ($properties->mime)
		{
			case 'image/gif':
				// Make sure the image type is supported.
				if (empty(self::$formats[IMAGETYPE_GIF]))
				{
					// @codeCoverageIgnoreStart
					$this->getLogger()->error('Attempting to load an image of unsupported type GIF.');

					throw new \RuntimeException('Attempting to load an image of unsupported type GIF.');

					// @codeCoverageIgnoreEnd
				}

				// Attempt to create the image handle.
				$handle = imagecreatefromgif($path);

				if (!is_resource($handle))
				{
					// @codeCoverageIgnoreStart
					throw new \RuntimeException('Unable to process GIF image.');

					// @codeCoverageIgnoreEnd
				}

				$this->handle = $handle;
				break;

			case 'image/jpeg':
				// Make sure the image type is supported.
				if (empty(self::$formats[IMAGETYPE_JPEG]))
				{
					// @codeCoverageIgnoreStart
					$this->getLogger()->error('Attempting to load an image of unsupported type JPG.');

					throw new \RuntimeException('Attempting to load an image of unsupported type JPG.');

					// @codeCoverageIgnoreEnd
				}

				// Attempt to create the image handle.
				$handle = imagecreatefromjpeg($path);

				if (!is_resource($handle))
				{
					// @codeCoverageIgnoreStart
					throw new \RuntimeException('Unable to process JPG image.');

					// @codeCoverageIgnoreEnd
				}

				$this->handle = $handle;
				break;

			case 'image/png':
				// Make sure the image type is supported.
				if (empty(self::$formats[IMAGETYPE_PNG]))
				{
					// @codeCoverageIgnoreStart
					$this->getLogger()->error('Attempting to load an image of unsupported type PNG.');

					throw new \RuntimeException('Attempting to load an image of unsupported type PNG.');

					// @codeCoverageIgnoreEnd
				}

				// Attempt to create the image handle.
				$handle = imagecreatefrompng($path);

				if (!is_resource($handle))
				{
					// @codeCoverageIgnoreStart
					throw new \RuntimeException('Unable to process PNG image.');

					// @codeCoverageIgnoreEnd
				}

				$this->handle = $handle;

				// Set transparency for non-transparent PNGs.
				if (!$this->isTransparent())
				{
					// Assign to black which is default for transparent PNGs
					$transparency = imagecolorallocatealpha($handle, 0, 0, 0, 127);

					imagecolortransparent($handle, $transparency);
				}

				break;

			default:
				$this->getLogger()->error('Attempting to load an image of unsupported type ' . $properties->mime);

				throw new \InvalidArgumentException('Attempting to load an image of unsupported type ' . $properties->mime);
		}

		// Set the filesystem path to the source image.
		$this->path = $path;
	}

	/**
	 * Method to resize the current image.
	 *
	 * @param   mixed    $width        The width of the resized image in pixels or a percentage.
	 * @param   mixed    $height       The height of the resized image in pixels or a percentage.
	 * @param   boolean  $createNew    If true the current image will be cloned, resized and returned; else
	 *                                 the current image will be resized and returned.
	 * @param   integer  $scaleMethod  Which method to use for scaling
	 *
	 * @return  Image
	 *
	 * @since   1.0
	 * @throws  \LogicException
	 */
	public function resize($width, $height, $createNew = true, $scaleMethod = self::SCALE_INSIDE)
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		// Sanitize width.
		$width = $this->sanitizeWidth($width, $height);

		// Sanitize height.
		$height = $this->sanitizeHeight($height, $width);

		// Prepare the dimensions for the resize operation.
		$dimensions = $this->prepareDimensions($width, $height, $scaleMethod);

		// Instantiate offset.
		$offset = new \stdClass;
		$offset->x = $offset->y = 0;

		// Center image if needed and create the new truecolor image handle.
		if ($scaleMethod == self::SCALE_FIT)
		{
			// Get the offsets
			$offset->x	= round(($width - $dimensions->width) / 2);
			$offset->y	= round(($height - $dimensions->height) / 2);

			$handle = imagecreatetruecolor($width, $height);

			// Make image transparent, otherwise canvas outside initial image would default to black
			if (!$this->isTransparent())
			{
				$transparency = imagecolorAllocateAlpha($this->handle, 0, 0, 0, 127);
				imagecolorTransparent($this->handle, $transparency);
			}
		}
		else
		{
			$handle = imagecreatetruecolor($dimensions->width, $dimensions->height);
		}

		// Allow transparency for the new image handle.
		imagealphablending($handle, false);
		imagesavealpha($handle, true);

		if ($this->isTransparent())
		{
			// Get the transparent color values for the current image.
			$rgba = imageColorsForIndex($this->handle, imagecolortransparent($this->handle));
			$color = imageColorAllocateAlpha($this->handle, $rgba['red'], $rgba['green'], $rgba['blue'], $rgba['alpha']);

			// Set the transparent color values for the new image.
			imagecolortransparent($handle, $color);
			imagefill($handle, 0, 0, $color);
		}

		// Use resampling for better quality
		imagecopyresampled(
			$handle, $this->handle,
			$offset->x, $offset->y, 0, 0, $dimensions->width, $dimensions->height, $this->getWidth(), $this->getHeight()
		);

		// If we are resizing to a new image, create a new JImage object.
		if ($createNew)
		{
			// @codeCoverageIgnoreStart
			$new = new Image($handle);

			return $new;

			// @codeCoverageIgnoreEnd
		}
		else
		// Swap out the current handle for the new image handle.
		{
			// Free the memory from the current handle
			$this->destroy();

			$this->handle = $handle;

			return $this;
		}
	}

	/**
	 * Method to crop an image after resizing it to maintain
	 * proportions without having to do all the set up work.
	 *
	 * @param   integer  $width      The desired width of the image in pixels or a percentage.
	 * @param   integer  $height     The desired height of the image in pixels or a percentage.
	 * @param   integer  $createNew  If true the current image will be cloned, resized, cropped and returned.
	 *
	 * @return  object  Image Object for chaining.
	 *
	 * @since   1.0
	 */
	public function cropResize($width, $height, $createNew = true)
	{
		$width   = $this->sanitizeWidth($width, $height);
		$height  = $this->sanitizeHeight($height, $width);

		if (($this->getWidth() / $width) < ($this->getHeight() / $height))
		{
			$this->resize($width, 0, false);
		}
		else
		{
			$this->resize(0, $height, false);
		}

		return $this->crop($width, $height, null, null, $createNew);
	}

	/**
	 * Method to rotate the current image.
	 *
	 * @param   mixed    $angle       The angle of rotation for the image
	 * @param   integer  $background  The background color to use when areas are added due to rotation
	 * @param   boolean  $createNew   If true the current image will be cloned, rotated and returned; else
	 *                                the current image will be rotated and returned.
	 *
	 * @return  Image
	 *
	 * @since   1.0
	 * @throws  \LogicException
	 */
	public function rotate($angle, $background = -1, $createNew = true)
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		// Sanitize input
		$angle = (float) $angle;

		// Create the new truecolor image handle.
		$handle = imagecreatetruecolor($this->getWidth(), $this->getHeight());

		// Allow transparency for the new image handle.
		imagealphablending($handle, false);
		imagesavealpha($handle, true);

		// Copy the image
		imagecopy($handle, $this->handle, 0, 0, 0, 0, $this->getWidth(), $this->getHeight());

		// Rotate the image
		$handle = imagerotate($handle, $angle, $background);

		// If we are resizing to a new image, create a new Image object.
		if ($createNew)
		{
			// @codeCoverageIgnoreStart
			$new = new Image($handle);

			return $new;

			// @codeCoverageIgnoreEnd
		}
		else
		// Swap out the current handle for the new image handle.
		{
			// Free the memory from the current handle
			$this->destroy();

			$this->handle = $handle;

			return $this;
		}
	}

	/**
	 * Method to write the current image out to a file or output directly.
	 *
	 * @param   mixed    $path     The filesystem path to save the image.
	 *                             When null, the raw image stream will be outputted directly.
	 * @param   integer  $type     The image type to save the file as.
	 * @param   array    $options  The image type options to use in saving the file.
	 *                             For PNG and JPEG formats use `quality` key to set compression level (0..9 and 0..100)
	 *
	 * @return  boolean
	 *
	 * @see     http://www.php.net/manual/image.constants.php
	 * @since   1.0
	 * @throws  \LogicException
	 */
	public function toFile($path, $type = IMAGETYPE_JPEG, array $options = array())
	{
		// Make sure the resource handle is valid.
		if (!$this->isLoaded())
		{
			throw new \LogicException('No valid image was loaded.');
		}

		switch ($type)
		{
			case IMAGETYPE_GIF:
				return imagegif($this->handle, $path);
				break;

			case IMAGETYPE_PNG:
				return imagepng($this->handle, $path, (array_key_exists('quality', $options)) ? $options['quality'] : 0);
				break;

			case IMAGETYPE_JPEG:
			default:
				return imagejpeg($this->handle, $path, (array_key_exists('quality', $options)) ? $options['quality'] : 100);
		}
	}

	/**
	 * Method to get an image filter instance of a specified type.
	 *
	 * @param   string  $type  The image filter type to get.
	 *
	 * @return  ImageFilter
	 *
	 * @since   1.0
	 * @throws  \RuntimeException
	 */
	protected function getFilterInstance($type)
	{
		// Sanitize the filter type.
		$type = strtolower(preg_replace('#[^A-Z0-9_]#i', '', $type));

		// Verify that the filter type exists.
		$className = 'Joomla\\Image\\Filter\\' . ucfirst($type);

		if (!class_exists($className))
		{
			$this->getLogger()->error('The ' . ucfirst($type) . ' image filter is not available.');

			throw new \RuntimeException('The ' . ucfirst($type) . ' image filter is not available.');
		}

		// Instantiate the filter object.
		$instance = new $className($this->handle);

		// Verify that the filter type is valid.
		if (!($instance instanceof ImageFilter))
		{
			// @codeCoverageIgnoreStart
			$this->getLogger()->error('The ' . ucfirst($type) . ' image filter is not valid.');

			throw new \RuntimeException('The ' . ucfirst($type) . ' image filter is not valid.');

			// @codeCoverageIgnoreEnd
		}

		return $instance;
	}

	/**
	 * Method to get the new dimensions for a resized image.
	 *
	 * @param   integer  $width        The width of the resized image in pixels.
	 * @param   integer  $height       The height of the resized image in pixels.
	 * @param   integer  $scaleMethod  The method to use for scaling
	 *
	 * @return  \stdClass
	 *
	 * @since   1.0
	 * @throws  \InvalidArgumentException  If width, height or both given as zero
	 */
	protected function prepareDimensions($width, $height, $scaleMethod)
	{
		// Instantiate variables.
		$dimensions = new \stdClass;

		switch ($scaleMethod)
		{
			case self::SCALE_FILL:
				$dimensions->width = (int) round($width);
				$dimensions->height = (int) round($height);
				break;

			case self::SCALE_INSIDE:
			case self::SCALE_OUTSIDE:
			case self::SCALE_FIT:
				$rx = ($width > 0) ? ($this->getWidth() / $width) : 0;
				$ry = ($height > 0) ? ($this->getHeight() / $height) : 0;

				if ($scaleMethod != self::SCALE_OUTSIDE)
				{
					$ratio = max($rx, $ry);
				}
				else
				{
					$ratio = min($rx, $ry);
				}

				$dimensions->width = (int) round($this->getWidth() / $ratio);
				$dimensions->height = (int) round($this->getHeight() / $ratio);
				break;

			default:
				throw new \InvalidArgumentException('Invalid scale method.');
				break;
		}

		return $dimensions;
	}

	/**
	 * Method to sanitize a height value.
	 *
	 * @param   mixed  $height  The input height value to sanitize.
	 * @param   mixed  $width   The input width value for reference.
	 *
	 * @return  integer
	 *
	 * @since   1.0
	 */
	protected function sanitizeHeight($height, $width)
	{
		// If no height was given we will assume it is a square and use the width.
		$height = ($height === null) ? $width : $height;

		// If we were given a percentage, calculate the integer value.
		if (preg_match('/^[0-9]+(\.[0-9]+)?\%$/', $height))
		{
			$height = (int) round($this->getHeight() * (float) str_replace('%', '', $height) / 100);
		}
		else
		// Else do some rounding so we come out with a sane integer value.
		{
			$height = (int) round((float) $height);
		}

		return $height;
	}

	/**
	 * Method to sanitize an offset value like left or top.
	 *
	 * @param   mixed  $offset  An offset value.
	 *
	 * @return  integer
	 *
	 * @since   1.0
	 */
	protected function sanitizeOffset($offset)
	{
		return (int) round((float) $offset);
	}

	/**
	 * Method to sanitize a width value.
	 *
	 * @param   mixed  $width   The input width value to sanitize.
	 * @param   mixed  $height  The input height value for reference.
	 *
	 * @return  integer
	 *
	 * @since   1.0
	 */
	protected function sanitizeWidth($width, $height)
	{
		// If no width was given we will assume it is a square and use the height.
		$width = ($width === null) ? $height : $width;

		// If we were given a percentage, calculate the integer value.
		if (preg_match('/^[0-9]+(\.[0-9]+)?\%$/', $width))
		{
			$width = (int) round($this->getWidth() * (float) str_replace('%', '', $width) / 100);
		}
		else
		// Else do some rounding so we come out with a sane integer value.
		{
			$width = (int) round((float) $width);
		}

		return $width;
	}

	/**
	 * Method to destroy an image handle and
	 * free the memory associated with the handle
	 *
	 * @return  boolean  True on success, false on failure or if no image is loaded
	 *
	 * @since   1.0
	 */
	public function destroy()
	{
		if ($this->isLoaded())
		{
			return imagedestroy($this->handle);
		}

		return false;
	}

	/**
	 * Method to call the destroy() method one last time
	 * to free any memory when the object is unset
	 *
	 * @see    Image::destroy()
	 * @since  1.0
	 */
	public function __destruct()
	{
		$this->destroy();
	}
}