<?php
/**
 * PhpThumb GD Thumb Class Definition File
 * 
 * This file contains the definition for the GdThumb object
 * 
 * PHP Version 5 with GD 2.0+
 * PhpThumb : PHP Thumb Library <http://phpthumb.gxdlabs.com>
 * Copyright (c) 2009, Ian Selby/Gen X Design
 * 
 * Author(s): Ian Selby <ian@gen-x-design.com>
 * 
 * Licensed under the MIT License
 * Redistributions of files must retain the above copyright notice.
 * 
 * @author Ian Selby <ian@gen-x-design.com>
 * @copyright Copyright (c) 2009 Gen X Design
 * @link http://phpthumb.gxdlabs.com
 * @license http://www.opensource.org/licenses/mit-license.php The MIT License
 * @version 3.0
 * @package PhpThumb
 * @filesource
 */

/**
 * GdThumb Class Definition
 * 
 * This is the GD Implementation of the PHP Thumb library.
 * 
 * @package PhpThumb
 * @subpackage Core
 */
class GdThumb extends ThumbBase
{
	/**
	 * The prior image (before manipulation)
	 * 
	 * @var resource
	 */
	protected $oldImage;
	/**
	 * The working image (used during manipulation)
	 * 
	 * @var resource
	 */
	protected $workingImage;
	/**
	 * The current dimensions of the image
	 * 
	 * @var array
	 */
	protected $currentDimensions;
	/**
	 * The new, calculated dimensions of the image
	 * 
	 * @var array
	 */
	protected $newDimensions;
	/**
	 * The options for this class
	 * 
	 * This array contains various options that determine the behavior in
	 * various functions throughout the class.  Functions note which specific 
	 * option key / values are used in their documentation
	 * 
	 * @var array
	 */
	protected $options;
	/**
	 * The maximum width an image can be after resizing (in pixels)
	 * 
	 * @var int
	 */
	protected $maxWidth;
	/**
	 * The maximum height an image can be after resizing (in pixels)
	 * 
	 * @var int
	 */
	protected $maxHeight;
	/**
	 * The percentage to resize the image by
	 * 
	 * @var int
	 */
	protected $percent;
	
	/**
	 * Class Constructor
	 * 
	 * @return GdThumb 
	 * @param string $fileName
	 */
	public function __construct ($fileName, $options = array(), $isDataStream = false)
	{
		parent::__construct($fileName, $isDataStream);
		
		$this->determineFormat();
		
		if ($this->isDataStream === false)
		{
			$this->verifyFormatCompatiblity();
		}
		
		switch ($this->format)
		{
			case 'GIF':
				$this->oldImage = imagecreatefromgif($this->fileName);
				break;
			case 'JPG':
				$this->oldImage = imagecreatefromjpeg($this->fileName);
				break;
			case 'PNG':
				$this->oldImage = imagecreatefrompng($this->fileName);
				break;
			case 'STRING':
				$this->oldImage = imagecreatefromstring($this->fileName);
				break;
		}
	
		$this->currentDimensions = array
		(
			'width' 	=> imagesx($this->oldImage),
			'height'	=> imagesy($this->oldImage)
		);
		
		$this->setOptions($options);
		
		// TODO: Port gatherImageMeta to a separate function that can be called to extract exif data
	}
	
	/**
	 * Class Destructor
	 * 
	 */
	public function __destruct ()
	{
		if (is_resource($this->oldImage))
		{
			imagedestroy($this->oldImage);
		}
		
		if (is_resource($this->workingImage))
		{
			imagedestroy($this->workingImage);
		}
	}
	
	##############################
	# ----- API FUNCTIONS ------ #
	##############################
	
	/**
	 * Resizes an image to be no larger than $maxWidth or $maxHeight
	 * 
	 * If either param is set to zero, then that dimension will not be considered as a part of the resize.
	 * Additionally, if $this->options['resizeUp'] is set to true (false by default), then this function will
	 * also scale the image up to the maximum dimensions provided.
	 * 
	 * @param int $maxWidth The maximum width of the image in pixels
	 * @param int $maxHeight The maximum height of the image in pixels
	 * @return GdThumb
	 */
	public function resize ($maxWidth = 0, $maxHeight = 0)
	{
		// make sure our arguments are valid
		if (!is_numeric($maxWidth))
		{
			throw new InvalidArgumentException('$maxWidth must be numeric');
		}
		
		if (!is_numeric($maxHeight))
		{
			throw new InvalidArgumentException('$maxHeight must be numeric');
		}
		
		// make sure we're not exceeding our image size if we're not supposed to
		if ($this->options['resizeUp'] === false)
		{
			$this->maxHeight	= (intval($maxHeight) > $this->currentDimensions['height']) ? $this->currentDimensions['height'] : $maxHeight;
			$this->maxWidth		= (intval($maxWidth) > $this->currentDimensions['width']) ? $this->currentDimensions['width'] : $maxWidth;
		}
		else
		{
			$this->maxHeight	= intval($maxHeight);
			$this->maxWidth		= intval($maxWidth);
		}
		
		// get the new dimensions...
		$this->calcImageSize($this->currentDimensions['width'], $this->currentDimensions['height']);
		
		// create the working image
		if (function_exists('imagecreatetruecolor'))
		{
			$this->workingImage = imagecreatetruecolor($this->newDimensions['newWidth'], $this->newDimensions['newHeight']);
		}
		else
		{
			$this->workingImage = imagecreate($this->newDimensions['newWidth'], $this->newDimensions['newHeight']);
		}
		
		$this->preserveAlpha();		
		
		// and create the newly sized image
		imagecopyresampled
		(
			$this->workingImage,
			$this->oldImage,
			0,
			0,
			0,
			0,
			$this->newDimensions['newWidth'],
			$this->newDimensions['newHeight'],
			$this->currentDimensions['width'],
			$this->currentDimensions['height']
		);

		// update all the variables and resources to be correct
		$this->oldImage 					= $this->workingImage;
		$this->currentDimensions['width'] 	= $this->newDimensions['newWidth'];
		$this->currentDimensions['height'] 	= $this->newDimensions['newHeight'];
		
		return $this;
	}
    
    public function resizeStrict ($maxWidth = 0, $maxHeight = 0)
    {
        // make sure we're not exceeding our image size if we're not supposed to
        $this->maxHeight    = intval($maxHeight);
        $this->maxWidth        = intval($maxWidth);
        
        
        // get the new dimensions...
        $this->calcImageSizeStrict($this->currentDimensions['width'], $this->currentDimensions['height']);
        
        // create the working image
        if (function_exists('imagecreatetruecolor'))
        {
            $this->workingImage = imagecreatetruecolor($this->newDimensions['newWidth'], $this->newDimensions['newHeight']);
        }
        else
        {
            $this->workingImage = imagecreate($this->newDimensions['newWidth'], $this->newDimensions['newHeight']);
        }
        
        $this->preserveAlpha();        
        
        // and create the newly sized image
        imagecopyresampled
        (
            $this->workingImage,
            $this->oldImage,
            0,
            0,
            0,
            0,
            $this->newDimensions['newWidth'],
            $this->newDimensions['newHeight'],
            $this->currentDimensions['width'],
            $this->currentDimensions['height']
        );

        // update all the variables and resources to be correct
        $this->oldImage                     = $this->workingImage;
        $this->currentDimensions['width']     = $this->newDimensions['newWidth'];
        $this->currentDimensions['height']     = $this->newDimensions['newHeight'];
        
        return $this;
    }
	
	/**
	 * Adaptively Resizes the Image
	 * 
	 * This function attempts to get the image to as close to the provided dimensions as possible, and then crops the 
	 * remaining overflow (from the center) to get the image to be the size specified
	 * 
	 * @param int $maxWidth
	 * @param int $maxHeight
	 * @return GdThumb
	 */
	public function adaptiveResize ($width, $height)
	{
		// make sure our arguments are valid
		if (!is_numeric($width) || $width  == 0)
		{
			throw new InvalidArgumentException('$width must be numeric and greater than zero');
		}
		
		if (!is_numeric($height) || $height == 0)
		{
			throw new InvalidArgumentException('$height must be numeric and greater than zero');
		}
		
		// make sure we're not exceeding our image size if we're not supposed to
		if ($this->options['resizeUp'] === false)
		{
			$this->maxHeight	= (intval($height) > $this->currentDimensions['height']) ? $this->currentDimensions['height'] : $height;
			$this->maxWidth		= (intval($width) > $this->currentDimensions['width']) ? $this->currentDimensions['width'] : $width;
		}
		else
		{
			$this->maxHeight	= intval($height);
			$this->maxWidth		= intval($width);
		}
		
		$this->calcImageSizeStrict($this->currentDimensions['width'], $this->currentDimensions['height']);
		
		// resize the image to be close to our desired dimensions
		$this->resize($this->newDimensions['newWidth'], $this->newDimensions['newHeight']);
		
		// reset the max dimensions...
		if ($this->options['resizeUp'] === false)
		{
			$this->maxHeight	= (intval($height) > $this->currentDimensions['height']) ? $this->currentDimensions['height'] : $height;
			$this->maxWidth		= (intval($width) > $this->currentDimensions['width']) ? $this->currentDimensions['width'] : $width;
		}
		else
		{
			$this->maxHeight	= intval($height);
			$this->maxWidth		= intval($width);
		}
		
		// create the working image
		if (function_exists('imagecreatetruecolor'))
		{
			$this->workingImage = imagecreatetruecolor($this->maxWidth, $this->maxHeight);
		}
		else
		{
			$this->workingImage = imagecreate($this->maxWidth, $this->maxHeight);
		}
		
		$this->preserveAlpha();
		
		$cropWidth	= $this->maxWidth;
		$cropHeight	= $this->maxHeight;
		$cropX 		= 0;
		$cropY 		= 0;
		
		// now, figure out how to crop the rest of the image...
		if ($this->currentDimensions['width'] > $this->maxWidth)
		{
			$cropX = intval(($this->currentDimensions['width'] - $this->maxWidth) / 2);
		}
		elseif ($this->currentDimensions['height'] > $this->maxHeight)
		{
			$cropY = intval(($this->currentDimensions['height'] - $this->maxHeight) / 2);
		}
		
		imagecopyresampled
		(
            $this->workingImage,
            $this->oldImage,
            0,
            0,
            $cropX,
            $cropY,
            $cropWidth,
            $cropHeight,
            $cropWidth,
            $cropHeight
		);
		
		// update all the variables and resources to be correct
		$this->oldImage 					= $this->workingImage;
		$this->currentDimensions['width'] 	= $this->maxWidth;
		$this->currentDimensions['height'] 	= $this->maxHeight;
		
		return $this;
	}
	
	/**
	 * Resizes an image by a given percent uniformly
	 * 
	 * Percentage should be whole number representation (i.e. 1-100)
	 * 
	 * @param int $percent
	 * @return GdThumb
	 */
	public function resizePercent ($percent = 0)
	{
		if (!is_numeric($percent))
		{
			throw new InvalidArgumentException ('$percent must be numeric');
		}
		
		$this->percent = intval($percent);
		
		$this->calcImageSizePercent($this->currentDimensions['width'], $this->currentDimensions['height']);
		
		if (function_exists('imagecreatetruecolor'))
		{
			$this->workingImage = imagecreatetruecolor($this->newDimensions['newWidth'], $this->newDimensions['newHeight']);
		}
		else
		{
			$this->workingImage = imagecreate($this->newDimensions['newWidth'], $this->newDimensions['newHeight']);
		}
		
		$this->preserveAlpha();
		
		ImageCopyResampled(
			$this->workingImage,
			$this->oldImage,
			0,
			0,
			0,
			0,
			$this->newDimensions['newWidth'],
			$this->newDimensions['newHeight'],
			$this->currentDimensions['width'],
			$this->currentDimensions['height']
		);

		$this->oldImage 					= $this->workingImage;
		$this->currentDimensions['width'] 	= $this->newDimensions['newWidth'];
		$this->currentDimensions['height'] 	= $this->newDimensions['newHeight'];
		
		return $this;
	}
	
	/**
	 * Crops an image from the center with provided dimensions
	 * 
	 * If no height is given, the width will be used as a height, thus creating a square crop
	 * 
	 * @param int $cropWidth
	 * @param int $cropHeight
	 * @return GdThumb
	 */
	public function cropFromCenter ($cropWidth, $cropHeight = null)
	{
		if (!is_numeric($cropWidth))
		{
			throw new InvalidArgumentException('$cropWidth must be numeric');
		}
		
		if ($cropHeight !== null && !is_numeric($cropHeight))
		{
			throw new InvalidArgumentException('$cropHeight must be numeric');
		}
		
		if ($cropHeight === null)
		{
			$cropHeight = $cropWidth;
		}
		
		$cropWidth	= ($this->currentDimensions['width'] < $cropWidth) ? $this->currentDimensions['width'] : $cropWidth;
		$cropHeight = ($this->currentDimensions['height'] < $cropHeight) ? $this->currentDimensions['height'] : $cropHeight;
		
		$cropX = intval(($this->currentDimensions['width'] - $cropWidth) / 2);
		$cropY = intval(($this->currentDimensions['height'] - $cropHeight) / 2);
		
		$this->crop($cropX, $cropY, $cropWidth, $cropHeight);
		
		return $this;
	}
	
	/**
	 * Vanilla Cropping - Crops from x,y with specified width and height
	 * 
	 * @param int $startX
	 * @param int $startY
	 * @param int $cropWidth
	 * @param int $cropHeight
	 * @return GdThumb
	 */
	public function crop ($startX, $startY, $cropWidth, $cropHeight)
	{
		// validate input
		if (!is_numeric($startX))
		{
			throw new InvalidArgumentException('$startX must be numeric');
		}
		
		if (!is_numeric($startY))
		{
			throw new InvalidArgumentException('$startY must be numeric');
		}
		
		if (!is_numeric($cropWidth))
		{
			throw new InvalidArgumentException('$cropWidth must be numeric');
		}
		
		if (!is_numeric($cropHeight))
		{
			throw new InvalidArgumentException('$cropHeight must be numeric');
		}
		
		// do some calculations
		$cropWidth	= ($this->currentDimensions['width'] < $cropWidth) ? $this->currentDimensions['width'] : $cropWidth;
		$cropHeight = ($this->currentDimensions['height'] < $cropHeight) ? $this->currentDimensions['height'] : $cropHeight;
		
		// ensure everything's in bounds
		if (($startX + $cropWidth) > $this->currentDimensions['width'])
		{
			$startX = ($this->currentDimensions['width'] - $cropWidth);
			
		}
		
		if (($startY + $cropHeight) > $this->currentDimensions['height'])
		{
			$startY = ($this->currentDimensions['height'] - $cropHeight);
		}
		
		if ($startX < 0) 
		{
			$startX = 0;
		}
		
	    if ($startY < 0) 
		{
			$startY = 0;
		}
		
		// create the working image
		if (function_exists('imagecreatetruecolor'))
		{
			$this->workingImage = imagecreatetruecolor($cropWidth, $cropHeight);
		}
		else
		{
			$this->workingImage = imagecreate($cropWidth, $cropHeight);
		}
		
		$this->preserveAlpha();
		
		imagecopyresampled
		(
			$this->workingImage,
			$this->oldImage,
			0,
			0,
			$startX,
			$startY,
			$cropWidth,
			$cropHeight,
			$cropWidth,
			$cropHeight
		);
		
		$this->oldImage 					= $this->workingImage;
		$this->currentDimensions['width'] 	= $cropWidth;
		$this->currentDimensions['height'] 	= $cropHeight;
		
		return $this;
	}
	
	/**
	 * Rotates image either 90 degrees clockwise or counter-clockwise
	 * 
	 * @param string $direction
	 * @retunrn GdThumb
	 */
	public function rotateImage ($direction = 'CW') 
	{
    	if ($direction == 'CW') 
		{
    		$this->rotateImageNDegrees(90);
    	}
    	else 
		{
			$this->rotateImageNDegrees(-90);
		}
		
		return $this;
    }
	
	/**
	 * Rotates image specified number of degrees
	 * 
	 * @param int $degrees
	 * @return GdThumb
	 */
	public function rotateImageNDegrees ($degrees)
	{
		if (!is_numeric($degrees))
		{
			throw new InvalidArgumentException('$degrees must be numeric');
		}
		
		if (!function_exists('imagerotate'))
		{
			throw new RuntimeException('Your version of GD does not support image rotation.');
		}
		
		$this->workingImage = imagerotate($this->oldImage, $degrees, 0);
    	
		$newWidth 							= $this->currentDimensions['height'];
    	$newHeight 							= $this->currentDimensions['width'];
		$this->oldImage 					= $this->workingImage;
		$this->currentDimensions['width'] 	= $newWidth;
		$this->currentDimensions['height'] 	= $newHeight;
		
		return $this;
	}
	
	/**
	 * Shows an image
	 * 
	 * This function will show the current image by first sending the appropriate header
	 * for the format, and then outputting the image data. If headers have already been sent, 
	 * a runtime exception will be thrown 
	 * 
	 * @param bool $rawData Whether or not the raw image stream should be output
	 * @return GdThumb
	 */
	public function show ($rawData = false) 
	{
		if (headers_sent())
		{
			throw new RuntimeException('Cannot show image, headers have already been sent');
		}
		
		switch ($this->format) 
		{
			case 'GIF':
				if ($rawData === false) 
				{ 
					header('Content-type: image/gif'); 
				}
				imagegif($this->oldImage);
				break;
			case 'JPG':
				if ($rawData === false) 
				{ 
					header('Content-type: image/jpeg'); 
				}
				imagejpeg($this->oldImage, null, $this->options['jpegQuality']);
				break;
			case 'PNG':
			case 'STRING':
				if ($rawData === false) 
				{ 
					header('Content-type: image/png'); 
				}
				imagepng($this->oldImage);
				break;
		}
		
		return $this;
	}
	
	/**
	 * Returns the Working Image as a String
	 *
	 * This function is useful for getting the raw image data as a string for storage in
	 * a database, or other similar things.
	 *
	 * @return string
	 */
	public function getImageAsString ()
	{
		$data = null;
		ob_start();
		$this->show(true);
		$data = ob_get_contents();
		ob_end_clean();
		
		return $data;
	}
	
	/**
	 * Saves an image
	 * 
	 * This function will make sure the target directory is writeable, and then save the image.
	 * 
	 * If the target directory is not writeable, the function will try to correct the permissions (if allowed, this
	 * is set as an option ($this->options['correctPermissions']).  If the target cannot be made writeable, then a
	 * RuntimeException is thrown.
	 * 
	 * TODO: Create additional paramter for color matte when saving images with alpha to non-alpha formats (i.e. PNG => JPG)
	 * 
	 * @param string $fileName The full path and filename of the image to save
	 * @param string $format The format to save the image in (optional, must be one of [GIF,JPG,PNG]
	 * @return GdThumb
	 */
	public function save ($fileName, $format = null)
	{
		$validFormats = array('GIF', 'JPG', 'PNG');
		$format = ($format !== null) ? strtoupper($format) : $this->format;
		
		if (!in_array($format, $validFormats))
		{
			throw new InvalidArgumentException ('Invalid format type specified in save function: ' . $format);
		}
		
		// make sure the directory is writeable
		if (!is_writeable(dirname($fileName)))
		{
			// try to correct the permissions
			if ($this->options['correctPermissions'] === true)
			{
				@chmod(dirname($fileName), 0777);
				
				// throw an exception if not writeable
				if (!is_writeable(dirname($fileName)))
				{
					throw new RuntimeException ('File is not writeable, and could not correct permissions: ' . $fileName);
				}
			}
			// throw an exception if not writeable
			else
			{
				throw new RuntimeException ('File not writeable: ' . $fileName);
			}
		}
		
		switch ($format) 
		{
			case 'GIF':
				imagegif($this->oldImage, $fileName);
				break;
			case 'JPG':
				imagejpeg($this->oldImage, $fileName, $this->options['jpegQuality']);
				break;
			case 'PNG':
				imagepng($this->oldImage, $fileName);
				break;
		}
		
		return $this;
	}
	
	#################################
	# ----- GETTERS / SETTERS ----- #
	#################################
	
	/**
	 * Sets $this->options to $options
	 * 
	 * @param array $options
	 */
	public function setOptions ($options = array())
	{
		// make sure we've got an array for $this->options (could be null)
		if (!is_array($this->options))
		{
			$this->options = array();
		}
		
		// make sure we've gotten a proper argument
		if (!is_array($options))
		{
			throw new InvalidArgumentException ('setOptions requires an array');
		}
		
		// we've yet to init the default options, so create them here
		if (sizeof($this->options) == 0)
		{
			$defaultOptions = array 
			(
				'resizeUp'				=> false,
				'jpegQuality'			=> 100,
				'correctPermissions'	=> false,
				'preserveAlpha'			=> true,
				'alphaMaskColor'		=> array (255, 255, 255),
				'preserveTransparency'	=> true,
				'transparencyMaskColor'	=> array (0, 0, 0)
			);
		}
		// otherwise, let's use what we've got already
		else
		{
			$defaultOptions = $this->options;
		}
		
		$this->options = array_merge($defaultOptions, $options);
	}
	
	/**
	 * Returns $currentDimensions.
	 *
	 * @see GdThumb::$currentDimensions
	 */
	public function getCurrentDimensions ()
	{
		return $this->currentDimensions;
	}
	
	/**
	 * Sets $currentDimensions.
	 *
	 * @param object $currentDimensions
	 * @see GdThumb::$currentDimensions
	 */
	public function setCurrentDimensions ($currentDimensions)
	{
		$this->currentDimensions = $currentDimensions;
	}
	
	/**
	 * Returns $maxHeight.
	 *
	 * @see GdThumb::$maxHeight
	 */
	public function getMaxHeight ()
	{
		return $this->maxHeight;
	}
	
	/**
	 * Sets $maxHeight.
	 *
	 * @param object $maxHeight
	 * @see GdThumb::$maxHeight
	 */
	public function setMaxHeight ($maxHeight)
	{
		$this->maxHeight = $maxHeight;
	}
	
	/**
	 * Returns $maxWidth.
	 *
	 * @see GdThumb::$maxWidth
	 */
	public function getMaxWidth ()
	{
		return $this->maxWidth;
	}
	
	/**
	 * Sets $maxWidth.
	 *
	 * @param object $maxWidth
	 * @see GdThumb::$maxWidth
	 */
	public function setMaxWidth ($maxWidth)
	{
		$this->maxWidth = $maxWidth;
	}
	
	/**
	 * Returns $newDimensions.
	 *
	 * @see GdThumb::$newDimensions
	 */
	public function getNewDimensions ()
	{
		return $this->newDimensions;
	}
	
	/**
	 * Sets $newDimensions.
	 *
	 * @param object $newDimensions
	 * @see GdThumb::$newDimensions
	 */
	public function setNewDimensions ($newDimensions)
	{
		$this->newDimensions = $newDimensions;
	}
	
	/**
	 * Returns $options.
	 *
	 * @see GdThumb::$options
	 */
	public function getOptions ()
	{
		return $this->options;
	}
	
	/**
	 * Returns $percent.
	 *
	 * @see GdThumb::$percent
	 */
	public function getPercent ()
	{
		return $this->percent;
	}
	
	/**
	 * Sets $percent.
	 *
	 * @param object $percent
	 * @see GdThumb::$percent
	 */
	public function setPercent ($percent)
	{
		$this->percent = $percent;
	} 
	
	/**
	 * Returns $oldImage.
	 *
	 * @see GdThumb::$oldImage
	 */
	public function getOldImage ()
	{
		return $this->oldImage;
	}
	
	/**
	 * Sets $oldImage.
	 *
	 * @param object $oldImage
	 * @see GdThumb::$oldImage
	 */
	public function setOldImage ($oldImage)
	{
		$this->oldImage = $oldImage;
	}
	
	/**
	 * Returns $workingImage.
	 *
	 * @see GdThumb::$workingImage
	 */
	public function getWorkingImage ()
	{
		return $this->workingImage;
	}
	
	/**
	 * Sets $workingImage.
	 *
	 * @param object $workingImage
	 * @see GdThumb::$workingImage
	 */
	public function setWorkingImage ($workingImage)
	{
		$this->workingImage = $workingImage;
	} 
	
	
	#################################
	# ----- UTILITY FUNCTIONS ----- #
	#################################
	
	/**
	 * Calculates a new width and height for the image based on $this->maxWidth and the provided dimensions
	 * 
	 * @return array 
	 * @param int $width
	 * @param int $height
	 */
	protected function calcWidth ($width, $height)
	{
		$newWidthPercentage	= (100 * $this->maxWidth) / $width;
		$newHeight			= ($height * $newWidthPercentage) / 100;
		
		return array
		(
			'newWidth'	=> intval($this->maxWidth),
			'newHeight'	=> intval($newHeight)
		);
	}
	
	/**
	 * Calculates a new width and height for the image based on $this->maxWidth and the provided dimensions
	 * 
	 * @return array 
	 * @param int $width
	 * @param int $height
	 */
	protected function calcHeight ($width, $height)
	{
		$newHeightPercentage	= (100 * $this->maxHeight) / $height;
		$newWidth 				= ($width * $newHeightPercentage) / 100;
		
		return array
		(
			'newWidth'	=> ceil($newWidth),
			'newHeight'	=> ceil($this->maxHeight)
		);
	}
	
	/**
	 * Calculates a new width and height for the image based on $this->percent and the provided dimensions
	 * 
	 * @return array 
	 * @param int $width
	 * @param int $height
	 */
	protected function calcPercent ($width, $height)
	{
		$newWidth	= ($width * $this->percent) / 100;
		$newHeight	= ($height * $this->percent) / 100;
		
		return array 
		(
			'newWidth'	=> ceil($newWidth),
			'newHeight'	=> ceil($newHeight)
		);
	}
	
	/**
	 * Calculates the new image dimensions
	 * 
	 * These calculations are based on both the provided dimensions and $this->maxWidth and $this->maxHeight
	 * 
	 * @param int $width
	 * @param int $height
	 */
	protected function calcImageSize ($width, $height)
	{
		$newSize = array
		(
			'newWidth'	=> $width,
			'newHeight'	=> $height
		);
		
		if ($this->maxWidth > 0)
		{
			$newSize = $this->calcWidth($width, $height);
			
			if ($this->maxHeight > 0 && $newSize['newHeight'] > $this->maxHeight)
			{
				$newSize = $this->calcHeight($newSize['newWidth'], $newSize['newHeight']);
			}
		}
		
		if ($this->maxHeight > 0)
		{
			$newSize = $this->calcHeight($width, $height);
			
			if ($this->maxWidth > 0 && $newSize['newWidth'] > $this->maxWidth)
			{
				$newSize = $this->calcWidth($newSize['newWidth'], $newSize['newHeight']);
			}
		}
		
		$this->newDimensions = $newSize;
	}
	
	/**
	 * Calculates new image dimensions, not allowing the width and height to be less than either the max width or height 
	 * 
	 * @param int $width
	 * @param int $height
	 */
	protected function calcImageSizeStrict ($width, $height)
	{
		// first, we need to determine what the longest resize dimension is..
		if ($this->maxWidth >= $this->maxHeight)
		{
			// and determine the longest original dimension
			if ($width > $height)
			{
				$newDimensions = $this->calcHeight($width, $height);
				
				if ($newDimensions['newWidth'] < $this->maxWidth)
				{
					$newDimensions = $this->calcWidth($width, $height);
				}
			}
			elseif ($height >= $width)
			{
				$newDimensions = $this->calcWidth($width, $height);
				
				if ($newDimensions['newHeight'] < $this->maxHeight)
				{
					$newDimensions = $this->calcHeight($width, $height);
				}
			}
		}
		elseif ($this->maxHeight > $this->maxWidth)
		{
			if ($width >= $height)
			{
				$newDimensions = $this->calcWidth($width, $height);
				
				if ($newDimensions['newHeight'] < $this->maxHeight)
				{
					$newDimensions = $this->calcHeight($width, $height);
				}
			}
			elseif ($height > $width)
			{
				$newDimensions = $this->calcHeight($width, $height);
				
				if ($newDimensions['newWidth'] < $this->maxWidth)
				{
					$newDimensions = $this->calcWidth($width, $height);
				}
			}
		}
		
		$this->newDimensions = $newDimensions;
	}
	
	/**
	 * Calculates new dimensions based on $this->percent and the provided dimensions
	 * 
	 * @param int $width
	 * @param int $height
	 */
	protected function calcImageSizePercent ($width, $height)
	{
		if ($this->percent > 0)
		{
			$this->newDimensions = $this->calcPercent($width, $height);
		}
	}
	
	/**
	 * Determines the file format by mime-type
	 * 
	 * This function will throw exceptions for invalid images / mime-types
	 * 
	 */
	protected function determineFormat ()
	{
		if ($this->isDataStream === true)
		{
			$this->format = 'STRING';
			return;
		}
		
		$formatInfo = getimagesize($this->fileName);
		
		// non-image files will return false
		if ($formatInfo === false)
		{
			if ($this->remoteImage)
			{
				$this->triggerError('Could not determine format of remote image: ' . $this->fileName);
			}
			else
			{
				$this->triggerError('File is not a valid image: ' . $this->fileName);
			}
			
			// make sure we really stop execution
			return;
		}
		
		$mimeType = isset($formatInfo['mime']) ? $formatInfo['mime'] : null;
		
		switch ($mimeType)
		{
			case 'image/gif':
				$this->format = 'GIF';
				break;
			case 'image/jpeg':
				$this->format = 'JPG';
				break;
			case 'image/png':
				$this->format = 'PNG';
				break;
			default:
				$this->triggerError('Image format not supported: ' . $mimeType);
		}
	}
	
	/**
	 * Makes sure the correct GD implementation exists for the file type
	 * 
	 */
	protected function verifyFormatCompatiblity ()
	{
		$isCompatible 	= true;
		$gdInfo			= gd_info();
		
		switch ($this->format)
		{
			case 'GIF':
				$isCompatible = $gdInfo['GIF Create Support'];
				break;
			case 'JPG':
				$isCompatible = (isset($gdInfo['JPG Support']) || isset($gdInfo['JPEG Support'])) ? true : false;
				break;
			case 'PNG':
				$isCompatible = $gdInfo[$this->format . ' Support'];
				break;
			default:
				$isCompatible = false;
		}
		
		if (!$isCompatible)
		{
			// one last check for "JPEG" instead
			$isCompatible = $gdInfo['JPEG Support'];
			
			if (!$isCompatible)
			{
				$this->triggerError('Your GD installation does not support ' . $this->format . ' image types');
			}
		}
	}
	
	/**
	 * Preserves the alpha or transparency for PNG and GIF files
	 * 
	 * Alpha / transparency will not be preserved if the appropriate options are set to false.
	 * Also, the GIF transparency is pretty skunky (the results aren't awesome), but it works like a 
	 * champ... that's the nature of GIFs tho, so no huge surprise.
	 * 
	 * This functionality was originally suggested by commenter Aimi (no links / site provided) - Thanks! :)
	 *   
	 */
	protected function preserveAlpha ()
	{
		if ($this->format == 'PNG' && $this->options['preserveAlpha'] === true)
		{
			imagealphablending($this->workingImage, false);
			
			$colorTransparent = imagecolorallocatealpha
			(
				$this->workingImage, 
				$this->options['alphaMaskColor'][0], 
				$this->options['alphaMaskColor'][1], 
				$this->options['alphaMaskColor'][2], 
				0
			);
			
			imagefill($this->workingImage, 0, 0, $colorTransparent);
			imagesavealpha($this->workingImage, true);
		}
		// preserve transparency in GIFs... this is usually pretty rough tho
		if ($this->format == 'GIF' && $this->options['preserveTransparency'] === true)
		{
			$colorTransparent = imagecolorallocate
			(
				$this->workingImage, 
				$this->options['transparencyMaskColor'][0], 
				$this->options['transparencyMaskColor'][1], 
				$this->options['transparencyMaskColor'][2] 
			);
			
			imagecolortransparent($this->workingImage, $colorTransparent);
			imagetruecolortopalette($this->workingImage, true, 256);
		}
	}
}