SimpleImage.php

<?php
/**
 * @package		SimpleImage class
 * @version		2.5.3
 * @author		Cory LaViska for A Beautiful Site, LLC. (http://www.abeautifulsite.net/)
 * @author		Nazar Mokrynskyi <nazar@mokrynskyi.com> - merging of forks, namespace support, PhpDoc editing, adaptive_resize() method, other fixes
 * @license		This software is licensed under the MIT license: http://opensource.org/licenses/MIT
 * @copyright	A Beautiful Site, LLC.
 *
 * @link https://github.com/claviska/SimpleImage
 *
 */



/**
 * Class SimpleImage
 * This class makes image manipulation in PHP as simple as possible.
 * @package SimpleImage
 *
 */
class SimpleImage {

	/**
	 * @var int Default output image quality
	 *
	 */
	public $quality = 80;

	protected $image, $filename, $original_info, $width, $height, $imagestring;

	/**
	 * Create instance and load an image, or create an image from scratch
	 *
	 * @param null|string	$filename	Path to image file (may be omitted to create image from scratch)
	 * @param int			$width		Image width (is used for creating image from scratch)
	 * @param int|null		$height		If omitted - assumed equal to $width (is used for creating image from scratch)
	 * @param null|string	$color		Hex color string, array(red, green, blue) or array(red, green, blue, alpha).
	 * 									Where red, green, blue - integers 0-255, alpha - integer 0-127<br>
	 * 									(is used for creating image from scratch)
	 *
	 * @return SimpleImage
	 * @throws Exception
	 *
	 */
	function __construct($filename = null, $width = null, $height = null, $color = null) {
		if ($filename) {
			$this->load($filename);
		} elseif ($width) {
			$this->create($width, $height, $color);
		}
		return $this;
	}
	
	/**
	 * Destroy image resource
	 *
	 */
	function __destruct() {
		if ($this->image) {
			imagedestroy($this->image);
		}
	}
	
	/**
	 * Adaptive resize
	 *
	 * This function has been deprecated and will be removed in an upcoming release. Please 
	 * update your code to use the `thumbnail()` method instead. The arguments for both 
	 * methods are exactly the same.
	 *
	 * @param int			$width
	 * @param int|null		$height	If omitted - assumed equal to $width
	 *
	 * @return SimpleImage
	 *
	 */
	function adaptive_resize($width, $height = null) {
		
		return $this->thumbnail($width, $height);
		
	}
	
	/**
	 * Rotates and/or flips an image automatically so the orientation will be correct (based on exif 'Orientation')
	 *
	 * @return SimpleImage
	 *
	 */
	function auto_orient() {
		
		switch ($this->original_info['exif']['Orientation']) {
			case 1:
				// Do nothing
				break;
			case 2:
				// Flip horizontal
				$this->flip('x');
				break;
			case 3:
				// Rotate 180 counterclockwise
				$this->rotate(-180);
				break;
			case 4:
				// vertical flip
				$this->flip('y');
				break;
			case 5:
				// Rotate 90 clockwise and flip vertically
				$this->flip('y');
				$this->rotate(90);
				break;
			case 6:
				// Rotate 90 clockwise
				$this->rotate(90);
				break;
			case 7:
				// Rotate 90 clockwise and flip horizontally
				$this->flip('x');
				$this->rotate(90);
				break;
			case 8:
				// Rotate 90 counterclockwise
				$this->rotate(-90);
				break;
		}
		
		return $this;
		
	}
	
	/**
	 * Best fit (proportionally resize to fit in specified width/height)
	 *
	 * Shrink the image proportionally to fit inside a $width x $height box
	 *
	 * @param int			$max_width
	 * @param int			$max_height
	 *
	 * @return	SimpleImage
	 *
	 */
	function best_fit($max_width, $max_height) {
		
		// If it already fits, there's nothing to do
		if ($this->width <= $max_width && $this->height <= $max_height) {
			return $this;
		}
		
		// Determine aspect ratio
		$aspect_ratio = $this->height / $this->width;
		
		// Make width fit into new dimensions
		if ($this->width > $max_width) {
			$width = $max_width;
			$height = $width * $aspect_ratio;
		} else {
			$width = $this->width;
			$height = $this->height;
		}
		
		// Make height fit into new dimensions
		if ($height > $max_height) {
			$height = $max_height;
			$width = $height / $aspect_ratio;
		}
		
		return $this->resize($width, $height);
		
	}
	
	/**
	 * Blur
	 *
	 * @param string		$type	selective|gaussian
	 * @param int			$passes	Number of times to apply the filter
	 *
	 * @return SimpleImage
	 *
	 */
	function blur($type = 'selective', $passes = 1) {
		switch (strtolower($type)) {
			case 'gaussian':
				$type = IMG_FILTER_GAUSSIAN_BLUR;
				break;
			default:
				$type = IMG_FILTER_SELECTIVE_BLUR;
				break;
		}
		for ($i = 0; $i < $passes; $i++) {
			imagefilter($this->image, $type);
		}
		return $this;
	}
	
	/**
	 * Brightness
	 *
	 * @param int			$level	Darkest = -255, lightest = 255
	 *
	 * @return SimpleImage
	 *
	 */
	function brightness($level) {
		imagefilter($this->image, IMG_FILTER_BRIGHTNESS, $this->keep_within($level, -255, 255));
		return $this;
	}
	
	/**
	 * Contrast
	 *
	 * @param int			$level	Min = -100, max = 100
	 *
	 * @return SimpleImage
	 *
	 *
	 */
	function contrast($level) {
		imagefilter($this->image, IMG_FILTER_CONTRAST, $this->keep_within($level, -100, 100));
		return $this;
	}
	
	/**
	 * Colorize
	 *
	 * @param string		$color		Hex color string, array(red, green, blue) or array(red, green, blue, alpha).
	 * 									Where red, green, blue - integers 0-255, alpha - integer 0-127
	 * @param float|int		$opacity	0-1
	 *
	 * @return SimpleImage
	 *
	 */
	function colorize($color, $opacity) {
		$rgba = $this->normalize_color($color);
		$alpha = $this->keep_within(127 - (127 * $opacity), 0, 127);
		imagefilter($this->image, IMG_FILTER_COLORIZE, $this->keep_within($rgba['r'], 0, 255), $this->keep_within($rgba['g'], 0, 255), $this->keep_within($rgba['b'], 0, 255), $alpha);
		return $this;
	}
	
	/**
	 * Create an image from scratch
	 *
	 * @param int			$width	Image width
	 * @param int|null		$height	If omitted - assumed equal to $width
	 * @param null|string	$color	Hex color string, array(red, green, blue) or array(red, green, blue, alpha).
	 * 								Where red, green, blue - integers 0-255, alpha - integer 0-127
	 *
	 * @return SimpleImage
	 *
	 */
	function create($width, $height = null, $color = null) {
		
		$height = $height ?: $width;
		$this->width = $width;
		$this->height = $height;
		$this->image = imagecreatetruecolor($width, $height);
		$this->original_info = array(
			'width' => $width,
			'height' => $height,
			'orientation' => $this->get_orientation(),
			'exif' => null,
			'format' => 'png',
			'mime' => 'image/png'
		);
		
		if ($color) {
			$this->fill($color);
		}
		
		return $this;
		
	}
	
	/**
	 * Crop an image
	 *
	 * @param int			$x1	Left
	 * @param int			$y1	Top
	 * @param int			$x2	Right
	 * @param int			$y2	Bottom
	 *
	 * @return SimpleImage
	 *
	 */
	function crop($x1, $y1, $x2, $y2) {
		
		// Determine crop size
		if ($x2 < $x1) {
			list($x1, $x2) = array($x2, $x1);
		}
		if ($y2 < $y1) {
			list($y1, $y2) = array($y2, $y1);
		}
		$crop_width = $x2 - $x1;
		$crop_height = $y2 - $y1;
		
		// Perform crop
		$new = imagecreatetruecolor($crop_width, $crop_height);
		imagealphablending($new, false);
		imagesavealpha($new, true);
		imagecopyresampled($new, $this->image, 0, 0, $x1, $y1, $crop_width, $crop_height, $crop_width, $crop_height);
		
		// Update meta data
		$this->width = $crop_width;
		$this->height = $crop_height;
		$this->image = $new;
		
		return $this;
		
	}
	
	/**
	 * Desaturate (grayscale)
	 *
	 * @return SimpleImage
	 *
	 */
	function desaturate() {
		imagefilter($this->image, IMG_FILTER_GRAYSCALE);
		return $this;
	}
	
	/**
	 * Edge Detect
	 *
	 * @return SimpleImage
	 *
	 */
	function edges() {
		imagefilter($this->image, IMG_FILTER_EDGEDETECT);
		return $this;
	}
	
	/**
	 * Emboss
	 *
	 * @return SimpleImage
	 *
	 */
	function emboss() {
		imagefilter($this->image, IMG_FILTER_EMBOSS);
		return $this;
	}
	
	/**
	 * Fill image with color
	 *
	 * @param string		$color	Hex color string, array(red, green, blue) or array(red, green, blue, alpha).
	 * 								Where red, green, blue - integers 0-255, alpha - integer 0-127
	 *
	 * @return SimpleImage
	 *
	 */
	function fill($color = '#000000') {
		
		$rgba = $this->normalize_color($color);
		$fill_color = imagecolorallocatealpha($this->image, $rgba['r'], $rgba['g'], $rgba['b'], $rgba['a']);
		imagealphablending($this->image, false);
		imagesavealpha($this->image, true);		
		imagefilledrectangle($this->image, 0, 0, $this->width, $this->height, $fill_color);
		
		return $this;
		
	}
	
	/**
	 * Fit to height (proportionally resize to specified height)
	 *
	 * @param int			$height
	 *
	 * @return SimpleImage
	 *
	 */
	function fit_to_height($height) {
		
		$aspect_ratio = $this->height / $this->width;
		$width = $height / $aspect_ratio;
		
		return $this->resize($width, $height);
		
	}
	
	/**
	 * Fit to width (proportionally resize to specified width)
	 *
	 * @param int			$width
	 *
	 * @return SimpleImage
	 *
	 */
	function fit_to_width($width) {
		
		$aspect_ratio = $this->height / $this->width;
		$height = $width * $aspect_ratio;
		
		return $this->resize($width, $height);
		
	}
	
	/**
	 * Flip an image horizontally or vertically
	 *
	 * @param string		$direction	x|y
	 *
	 * @return SimpleImage
	 *
	 */
	function flip($direction) {
		
		$new = imagecreatetruecolor($this->width, $this->height);
		imagealphablending($new, false);
		imagesavealpha($new, true);
		
		switch (strtolower($direction)) {
			case 'y':
				for ($y = 0; $y < $this->height; $y++) {
					imagecopy($new, $this->image, 0, $y, 0, $this->height - $y - 1, $this->width, 1);
				}
				break;
			default:
				for ($x = 0; $x < $this->width; $x++) {
					imagecopy($new, $this->image, $x, 0, $this->width - $x - 1, 0, 1, $this->height);
				}
				break;
		}
		
		$this->image = $new;
		
		return $this;
		
	}
	
	/**
	 * Get the current height
	 *
	 * @return int
	 *
	 */
	function get_height() {
		return $this->height;
	}
	
	/**
	 * Get the current orientation
	 *
	 * @return string	portrait|landscape|square
	 *
	 */
	function get_orientation() {
		
		if (imagesx($this->image) > imagesy($this->image)) {
			return 'landscape';
		}
		
		if (imagesx($this->image) < imagesy($this->image)) {
			return 'portrait';
		}
		
		return 'square';
		
	}
	
	/**
	 * Get info about the original image
	 *
	 * @return array <pre> array(
	 * 	width        => 320,
	 * 	height       => 200,
	 * 	orientation  => ['portrait', 'landscape', 'square'],
	 * 	exif         => array(...),
	 * 	mime         => ['image/jpeg', 'image/gif', 'image/png'],
	 * 	format       => ['jpeg', 'gif', 'png']
	 * )</pre>
	 *
	 */
	function get_original_info() {
		return $this->original_info;
	}
	
	/**
	 * Get the current width
	 *
	 * @return int
	 *
	 */
	function get_width() {
		return $this->width;
	}
	
	/**
	 * Invert
	 *
	 * @return SimpleImage
	 *
	 */
	function invert() {
		imagefilter($this->image, IMG_FILTER_NEGATE);
		return $this;
	}
	
	/**
	 * Load an image
	 *
	 * @param string		$filename	Path to image file
	 *
	 * @return SimpleImage
	 * @throws Exception
	 *
	 */
	function load($filename) {
		
		// Require GD library
		if (!extension_loaded('gd')) {
			throw new Exception('Required extension GD is not loaded.');
		}
		$this->filename = $filename;
		return $this->get_meta_data();
	}
	
	/**
	 * Load a base64 string as image
	 *
	 * @param string		$filename	base64 string
	 *
	 * @return SimpleImage
	 * 
	 */ 
	function load_base64($base64string) {
		if (!extension_loaded('gd')) {
			throw new Exception('Required extension GD is not loaded.');
		}
		//remove data URI scheme and spaces from base64 string then decode it
		$this->imagestring = base64_decode(str_replace(' ', '+',preg_replace('#^data:image/[^;]+;base64,#', '', $base64string)));
		$this->image = imagecreatefromstring($this->imagestring);
		return $this->get_meta_data();
	}
	
	/**
	 * Mean Remove
	 *
	 * @return SimpleImage
	 *
	 */
	function mean_remove() {
		imagefilter($this->image, IMG_FILTER_MEAN_REMOVAL);
		return $this;
	}
	
	/**
	 * Changes the opacity level of the image
	 *
	 * @param float|int		$opacity	0-1
	 *
	 * @throws Exception
	 *
	 */
	function opacity($opacity) {
		
		// Determine opacity
		$opacity = $this->keep_within($opacity, 0, 1) * 100;
		
		// Make a copy of the image
		$copy = imagecreatetruecolor($this->width, $this->height);
		imagealphablending($copy, false);
		imagesavealpha($copy, true);		
		imagecopy($copy, $this->image, 0, 0, 0, 0, $this->width, $this->height);
		
		// Create transparent layer
		$this->create($this->width, $this->height, array(0, 0, 0, 127));
		
		// Merge with specified opacity
		$this->imagecopymerge_alpha($this->image, $copy, 0, 0, 0, 0, $this->width, $this->height, $opacity);
		imagedestroy($copy);
		
		return $this;
		
	}
	
	/**
	 * Outputs image without saving
	 *
	 * @param null|string	$format		If omitted or null - format of original file will be used, may be gif|jpg|png
	 * @param int|null		$quality	Output image quality in percents 0-100
	 *
	 * @throws Exception
	 *
	 */
	function output($format = null, $quality = null) {
		
		// Determine quality
		$quality = $quality ?: $this->quality;
		
		// Determine mimetype
		switch (strtolower($format)) {
			case 'gif':
				$mimetype = 'image/gif';
				break;
			case 'jpeg':
			case 'jpg':
				imageinterlace($this->image, true);
				$mimetype = 'image/jpeg';
				break;
			case 'png':
				$mimetype = 'image/png';
				break;
			default:
				$info = (empty($this->imagestring)) ? getimagesize($this->filename) : getimagesizefromstring($this->imagestring);
				$mimetype = $info['mime'];
				unset($info);
				break;
		}
		
		// Output the image
		header('Content-Type: '.$mimetype);
		switch ($mimetype) {
			case 'image/gif':
				imagegif($this->image);
				break;
			case 'image/jpeg':
				imagejpeg($this->image, null, round($quality));
				break;
			case 'image/png':
				imagepng($this->image, null, round(9 * $quality / 100));
				break;
			default:
				throw new Exception('Unsupported image format: '.$this->filename);
				break;
		}
		
		// Since no more output can be sent, call the destructor to free up memory
		$this->__destruct();
		
	}
	
	/**
	 * Outputs image as data base64 to use as img src
	 *
	 * @param null|string	$format		If omitted or null - format of original file will be used, may be gif|jpg|png
	 * @param int|null		$quality	Output image quality in percents 0-100
	 *
	 * @return string
	 * @throws Exception
	 *
	 */
	function output_base64($format = null, $quality = null) {
		
		// Determine quality
		$quality = $quality ?: $this->quality;
		
		// Determine mimetype
		switch (strtolower($format)) {
			case 'gif':
				$mimetype = 'image/gif';
				break;
			case 'jpeg':
			case 'jpg':
				imageinterlace($this->image, true);
				$mimetype = 'image/jpeg';
				break;
			case 'png':
				$mimetype = 'image/png';
				break;
			default:
				$info = getimagesize($this->filename);
				$mimetype = $info['mime'];
				unset($info);
				break;
		}
		
		// Output the image
		ob_start();
		switch ($mimetype) {
			case 'image/gif':
				imagegif($this->image);
				break;
			case 'image/jpeg':
				imagejpeg($this->image, null, round($quality));
				break;
			case 'image/png':
				imagepng($this->image, null, round(9 * $quality / 100));
				break;
			default:
				throw new Exception('Unsupported image format: '.$this->filename);
				break;
		}
		$image_data = ob_get_contents();
		ob_end_clean();
		
		// Returns formatted string for img src
		return 'data:'.$mimetype.';base64,'.base64_encode($image_data);
		
	}
	
	/**
	 * Overlay
	 *
	 * Overlay an image on top of another, works with 24-bit PNG alpha-transparency
	 *
	 * @param string		$overlay		An image filename or a SimpleImage object
	 * @param string		$position		center|top|left|bottom|right|top left|top right|bottom left|bottom right
	 * @param float|int		$opacity		Overlay opacity 0-1
	 * @param int			$x_offset		Horizontal offset in pixels
	 * @param int			$y_offset		Vertical offset in pixels
	 *
	 * @return SimpleImage
	 *
	 */
	function overlay($overlay, $position = 'center', $opacity = 1, $x_offset = 0, $y_offset = 0) {
		
		// Load overlay image
		if( !($overlay instanceof SimpleImage) ) {
			$overlay = new SimpleImage($overlay);
		}
		
		// Convert opacity
		$opacity = $opacity * 100;
		
		// Determine position
		switch (strtolower($position)) {
			case 'top left':
				$x = 0 + $x_offset;
				$y = 0 + $y_offset;
				break;
			case 'top right':
				$x = $this->width - $overlay->width + $x_offset;
				$y = 0 + $y_offset;
				break;
			case 'top':
				$x = ($this->width / 2) - ($overlay->width / 2) + $x_offset;
				$y = 0 + $y_offset;
				break;
			case 'bottom left':
				$x = 0 + $x_offset;
				$y = $this->height - $overlay->height + $y_offset;
				break;
			case 'bottom right':
				$x = $this->width - $overlay->width + $x_offset;
				$y = $this->height - $overlay->height + $y_offset;
				break;
			case 'bottom':
				$x = ($this->width / 2) - ($overlay->width / 2) + $x_offset;
				$y = $this->height - $overlay->height + $y_offset;
				break;
			case 'left':
				$x = 0 + $x_offset;
				$y = ($this->height / 2) - ($overlay->height / 2) + $y_offset;
				break;
			case 'right':
				$x = $this->width - $overlay->width + $x_offset;
				$y = ($this->height / 2) - ($overlay->height / 2) + $y_offset;
				break;
			case 'center':
			default:
				$x = ($this->width / 2) - ($overlay->width / 2) + $x_offset;
				$y = ($this->height / 2) - ($overlay->height / 2) + $y_offset;
				break;
		}
		
		// Perform the overlay
		$this->imagecopymerge_alpha($this->image, $overlay->image, $x, $y, 0, 0, $overlay->width, $overlay->height, $opacity);
		
		return $this;
		
	}
	
	/**
	 * Pixelate
	 *
	 * @param int			$block_size	Size in pixels of each resulting block
	 *
	 * @return SimpleImage
	 *
	 */
	function pixelate($block_size = 10) {
		imagefilter($this->image, IMG_FILTER_PIXELATE, $block_size, true);
		return $this;
	}
	
	/**
	 * Resize an image to the specified dimensions
	 *
	 * @param int	$width
	 * @param int	$height
	 *
	 * @return SimpleImage
	 *
	 */
	function resize($width, $height) {
		
		// Generate new GD image
		$new = imagecreatetruecolor($width, $height);
		
		if( $this->original_info['format'] === 'gif' ) {
			// Preserve transparency in GIFs
			$transparent_index = imagecolortransparent($this->image);
			if ($transparent_index >= 0) {
	            $transparent_color = imagecolorsforindex($this->image, $transparent_index);
	            $transparent_index = imagecolorallocate($new, $transparent_color['red'], $transparent_color['green'], $transparent_color['blue']);
	            imagefill($new, 0, 0, $transparent_index);
	            imagecolortransparent($new, $transparent_index);
			}
		} else {
			// Preserve transparency in PNGs (benign for JPEGs)
			imagealphablending($new, false);
			imagesavealpha($new, true);
		}
		
		// Resize
		imagecopyresampled($new, $this->image, 0, 0, 0, 0, $width, $height, $this->width, $this->height);
		
		// Update meta data
		$this->width = $width;
		$this->height = $height;
		$this->image = $new;
		
		return $this;
		
	}
	
	/**
	 * Rotate an image
	 *
	 * @param int			$angle		0-360
	 * @param string		$bg_color	Hex color string, array(red, green, blue) or array(red, green, blue, alpha).
	 * 									Where red, green, blue - integers 0-255, alpha - integer 0-127
	 *
	 * @return SimpleImage
	 *
	 */
	function rotate($angle, $bg_color = '#000000') {
		
		// Perform the rotation
		$rgba = $this->normalize_color($bg_color);
		$bg_color = imagecolorallocatealpha($this->image, $rgba['r'], $rgba['g'], $rgba['b'], $rgba['a']);
		$new = imagerotate($this->image, -($this->keep_within($angle, -360, 360)), $bg_color);
		imagesavealpha($new, true);
		imagealphablending($new, true);
		
		// Update meta data
		$this->width = imagesx($new);
		$this->height = imagesy($new);
		$this->image = $new;
		
		return $this;
		
	}
	
	/**
	 * Save an image
	 *
	 * The resulting format will be determined by the file extension.
	 *
	 * @param null|string	$filename	If omitted - original file will be overwritten
	 * @param null|int		$quality	Output image quality in percents 0-100
	 *
	 * @return SimpleImage
	 * @throws Exception
	 *
	 */
	function save($filename = null, $quality = null) {
		
		// Determine quality, filename, and format
		$quality = $quality ?: $this->quality;
		$filename = $filename ?: $this->filename;
		$format = $this->file_ext($filename) ?: $this->original_info['format'];
		
		// Create the image
		switch (strtolower($format)) {
			case 'gif':
				$result = imagegif($this->image, $filename);
				break;
			case 'jpg':
			case 'jpeg':
				imageinterlace($this->image, true);
				$result = imagejpeg($this->image, $filename, round($quality));
				break;
			case 'png':
				$result = imagepng($this->image, $filename, round(9 * $quality / 100));
				break;
			default:
				throw new Exception('Unsupported format');
		}
		
		if (!$result) {
			throw new Exception('Unable to save image: ' . $filename);
		}
		
		return $this;
		
	}
	
	/**
	 * Sepia
	 *
	 * @return SimpleImage
	 *
	 */
	function sepia() {
		imagefilter($this->image, IMG_FILTER_GRAYSCALE);
		imagefilter($this->image, IMG_FILTER_COLORIZE, 100, 50, 0);
		return $this;
	}
	
	/**
	 * Sketch
	 *
	 * @return SimpleImage
	 *
	 */
	function sketch() {
		imagefilter($this->image, IMG_FILTER_MEAN_REMOVAL);
		return $this;
	}
	
	/**
	 * Smooth
	 *
	 * @param int			$level	Min = -10, max = 10
	 *
	 * @return SimpleImage
	 *
	 */
	function smooth($level) {
		imagefilter($this->image, IMG_FILTER_SMOOTH, $this->keep_within($level, -10, 10));
		return $this;
	}
	
	/**
	 * Add text to an image
	 *
	 * @param string		$text
	 * @param string		$font_file
	 * @param float|int		$font_size
	 * @param string		$color
	 * @param string		$position
	 * @param int			$x_offset
	 * @param int			$y_offset
	 *
	 * @return SimpleImage
	 * @throws Exception
	 *
	 */
	function text($text, $font_file, $font_size = 12, $color = '#000000', $position = 'center', $x_offset = 0, $y_offset = 0) {
		
		// todo - this method could be improved to support the text angle
		$angle = 0;
		
		// Determine text color
		$rgba = $this->normalize_color($color);
		$color = imagecolorallocatealpha($this->image, $rgba['r'], $rgba['g'], $rgba['b'], $rgba['a']);
		
		// Determine textbox size
		$box = imagettfbbox($font_size, $angle, $font_file, $text);
		if (!$box) {
			throw new Exception('Unable to load font: '.$font_file);
		}
		$box_width = abs($box[6] - $box[2]);
		$box_height = abs($box[7] - $box[1]);
		
		// Determine position
		switch (strtolower($position)) {
			case 'top left':
				$x = 0 + $x_offset;
				$y = 0 + $y_offset + $box_height;
				break;
			case 'top right':
				$x = $this->width - $box_width + $x_offset;
				$y = 0 + $y_offset + $box_height;
				break;
			case 'top':
				$x = ($this->width / 2) - ($box_width / 2) + $x_offset;
				$y = 0 + $y_offset + $box_height;
				break;
			case 'bottom left':
				$x = 0 + $x_offset;
				$y = $this->height - $box_height + $y_offset + $box_height;
				break;
			case 'bottom right':
				$x = $this->width - $box_width + $x_offset;
				$y = $this->height - $box_height + $y_offset + $box_height;
				break;
			case 'bottom':
				$x = ($this->width / 2) - ($box_width / 2) + $x_offset;
				$y = $this->height - $box_height + $y_offset + $box_height;
				break;
			case 'left':
				$x = 0 + $x_offset;
				$y = ($this->height / 2) - (($box_height / 2) - $box_height) + $y_offset;
				break;
			case 'right';
				$x = $this->width - $box_width + $x_offset;
				$y = ($this->height / 2) - (($box_height / 2) - $box_height) + $y_offset;
				break;
			case 'center':
			default:
				$x = ($this->width / 2) - ($box_width / 2) + $x_offset;
				$y = ($this->height / 2) - (($box_height / 2) - $box_height) + $y_offset;
				break;
		}
		
		// Add the text
		imagettftext($this->image, $font_size, $angle, $x, $y, $color, $font_file, $text);
	
		return $this;
		
	}
	
	/**
	 * Thumbnail
	 *
	 * 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. Useful for generating thumbnails.
	 *
	 * @param int			$width
	 * @param int|null		$height	If omitted - assumed equal to $width
	 *
	 * @return SimpleImage
	 *
	 */
	function thumbnail($width, $height = null) {
		
		// Determine height
		$height = $height ?: $width;
		
		// Determine aspect ratios
		$current_aspect_ratio = $this->height / $this->width;
		$new_aspect_ratio = $height / $width;
		
		// Fit to height/width
		if ($new_aspect_ratio > $current_aspect_ratio) {
			$this->fit_to_height($height);
		} else {
			$this->fit_to_width($width);
		}
		$left = floor(($this->width / 2) - ($width / 2));
		$top = floor(($this->height / 2) - ($height / 2));
		
		// Return trimmed image
		return $this->crop($left, $top, $width + $left, $height + $top);
		
	}	
	
	/**
	 * Returns the file extension of the specified file
	 *
	 * @param string	$filename
	 *
	 * @return string
	 *
	 */
	protected function file_ext($filename) {
		
		if (!preg_match('/\./', $filename)) {
			return '';
		}
		
		return preg_replace('/^.*\./', '', $filename);
		
	}
	
	/**
	 * Get meta data of image or base64 string
	 *
	 * @param string|null		$imagestring	If omitted treat as a normal image
	 *
	 * @return SimpleImage
	 * @throws Exception
	 * 
	 */ 
	protected function get_meta_data() {
		//gather meta data
		if(empty($this->imagestring)) {
			$info = getimagesize($this->filename);
			
			switch ($info['mime']) {
				case 'image/gif':
					$this->image = imagecreatefromgif($this->filename);
					break;
				case 'image/jpeg':
					$this->image = imagecreatefromjpeg($this->filename);
					break;
				case 'image/png':
					$this->image = imagecreatefrompng($this->filename);
					break;
				default:
					throw new Exception('Invalid image: '.$this->filename);
					break;
			}
		} elseif (function_exists('getimagesizefromstring')) {
			$info = getimagesizefromstring($this->imagestring);
		} else {
			throw new Exception('PHP 5.4 is required to use method getimagesizefromstring');
		}
		
		$this->original_info = array(
			'width' => $info[0],
			'height' => $info[1],
			'orientation' => $this->get_orientation(),
			'exif' => function_exists('exif_read_data') && $info['mime'] === 'image/jpeg' && $this->imagestring === null ? $this->exif = @exif_read_data($this->filename) : null,
			'format' => preg_replace('/^image\//', '', $info['mime']),
			'mime' => $info['mime']
		);
		$this->width = $info[0];
		$this->height = $info[1];
		
		imagesavealpha($this->image, true);
		imagealphablending($this->image, true);
		
		return $this;
		
	}
	
	/**
	 * Same as PHP's imagecopymerge() function, except preserves alpha-transparency in 24-bit PNGs
	 *
	 * @param $dst_im
	 * @param $src_im
	 * @param $dst_x
	 * @param $dst_y
	 * @param $src_x
	 * @param $src_y
	 * @param $src_w
	 * @param $src_h
	 * @param $pct
	 *
	 * @link http://www.php.net/manual/en/function.imagecopymerge.php#88456
	 *
	 */
	protected function imagecopymerge_alpha($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h, $pct) {
		
		// Get image width and height and percentage
		$pct /= 100;
		$w = imagesx($src_im);
		$h = imagesy($src_im);
		
		// Turn alpha blending off
		imagealphablending($src_im, false);
		
		// Find the most opaque pixel in the image (the one with the smallest alpha value)
		$minalpha = 127;
		for ($x = 0; $x < $w; $x++) {
			for ($y = 0; $y < $h; $y++) {
				$alpha = (imagecolorat($src_im, $x, $y) >> 24) & 0xFF;
				if ($alpha < $minalpha) {
					$minalpha = $alpha;
				}
			}
		}
		
		// Loop through image pixels and modify alpha for each
		for ($x = 0; $x < $w; $x++) {
			for ($y = 0; $y < $h; $y++) {
				// Get current alpha value (represents the TANSPARENCY!)
				$colorxy = imagecolorat($src_im, $x, $y);
				$alpha = ($colorxy >> 24) & 0xFF;
				// Calculate new alpha
				if ($minalpha !== 127) {
					$alpha = 127 + 127 * $pct * ($alpha - 127) / (127 - $minalpha);
				} else {
					$alpha += 127 * $pct;
				}
				// Get the color index with new alpha
				$alphacolorxy = imagecolorallocatealpha($src_im, ($colorxy >> 16) & 0xFF, ($colorxy >> 8) & 0xFF, $colorxy & 0xFF, $alpha);
				// Set pixel with the new color + opacity
				if (!imagesetpixel($src_im, $x, $y, $alphacolorxy)) {
					return;
				}
			}
		}
		
		// Copy it
		imagesavealpha($dst_im, true);
		imagealphablending($dst_im, true);
		imagesavealpha($src_im, true);
		imagealphablending($src_im, true);
		imagecopy($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h);
		
	}
	
	/**
	 * Ensures $value is always within $min and $max range.
	 *
	 * If lower, $min is returned. If higher, $max is returned.
	 *
	 * @param int|float		$value
	 * @param int|float		$min
	 * @param int|float		$max
	 *
	 * @return int|float
	 *
	 */
	protected function keep_within($value, $min, $max) {
		
		if ($value < $min) {
			return $min;
		}
		
		if ($value > $max) {
			return $max;
		}
		
		return $value;
		
	}
	
	/**
	 * Converts a hex color value to its RGB equivalent
	 *
	 * @param string		$color	Hex color string, array(red, green, blue) or array(red, green, blue, alpha).
	 * 								Where red, green, blue - integers 0-255, alpha - integer 0-127
	 *
	 * @return array|bool
	 *
	 */
	protected function normalize_color($color) {
		
		if (is_string($color)) {
			
			$color = trim($color, '#');
			
			if (strlen($color) == 6) {
				list($r, $g, $b) = array(
					$color[0].$color[1],
					$color[2].$color[3],
					$color[4].$color[5]
				);
			} elseif (strlen($color) == 3) {
				list($r, $g, $b) = array(
					$color[0].$color[0],
					$color[1].$color[1],
					$color[2].$color[2]
				);
			} else {
				return false;
			}
			return array(
				'r' => hexdec($r),
				'g' => hexdec($g),
				'b' => hexdec($b),
				'a' => 0
			);
			
		} elseif (is_array($color) && (count($color) == 3 || count($color) == 4)) {
			
			if (isset($color['r'], $color['g'], $color['b'])) {
				return array(
					'r' => $this->keep_within($color['r'], 0, 255),
					'g' => $this->keep_within($color['g'], 0, 255),
					'b' => $this->keep_within($color['b'], 0, 255),
					'a' => $this->keep_within(isset($color['a']) ? $color['a'] : 0, 0, 127)
				);
			} elseif (isset($color[0], $color[1], $color[2])) {
				return array(
					'r' => $this->keep_within($color[0], 0, 255),
					'g' => $this->keep_within($color[1], 0, 255),
					'b' => $this->keep_within($color[2], 0, 255),
					'a' => $this->keep_within(isset($color[3]) ? $color[3] : 0, 0, 127)
				);
			}
			
		}
		return false;
	}
	
}