<?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;
    }

    /**
     * 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);
        }
    }
}
