PHP Thumbnail class

This PHP class creates thumbnails of jpeg, jpg, png or gif files. It uses GD and PHP. The thumbnails are saved to a specified location on disk after creation.

If only width or height of the thumbnail are specified, the image is scaled maintaining correct proportions. If both width and height of the thumb are specified, proportions are disregarded.

Also the 'maxLength' argument can be used to just specify the maximum length of the longest side of the thumbnail so that either width or height are scaled to the specified pixel value based on which is longest. In this case proportions are kept.

<?php
class Thumbnailer {
	private $image = ''; //image filename and path 
	private $sizes = null;
	public function __construct($image = false){
		if($image){
			 $this->setImage($image);			
		}
	}
 
	public function setImage($image){
		if (is_file($image) && ($this->sizes = getimagesize($image))) $this->image = $image;
	}
 
	/*  createThumb creates and saves a thumbnail 
	*	requires an $outputPath including filename to save thumbnail  file to;	
	*	specifications = array(maxLength=>100,width=>100,height=100,mime=>'image/jpeg')
	*/
	public function createThumb(Array $specifications,$outputPath){		
		if (!strlen($this->image)) return;
		$sizes = $this->sizes; 
		$originalImage = $this->loadImage($this->image, $sizes['mime']);
		$newWidth = 0; 
		$newHeight = 0; 
 
		if (isset($specifications['width']) && !isset($specifications['height'])){
			$newWidth = $specifications['width'];
			$newHeight = $sizes[1]*($newWidth/$sizes[0]); 
		}elseif(isset($specifications['height']) && !isset($specifications['width'])){
			$newHeight = $specifications['height'];			
			$newWidth = $sizes[0]*($newHeight/$sizes[1]);
		}elseif(isset($specifications['height']) && isset($specifications['width'])){
			$newWidth = $specifications['width'];
			$newHeight = $specifications['height'];			
		}elseif(isset($specifications['maxLength'])){
 
			if ($sizes[0] >= $sizes[1]){
				$newWidth = $specifications['maxLength'];
				$newHeight = $sizes[1]*($newWidth/$sizes[0]); 
			}else{
				$newHeight = $specifications['maxLength'];
				$newWidth = $sizes[0]*($newHeight/$sizes[1]);
			}
		}else{
			$newWidth = $sizes[0];
			$newHeight = $sizes[1];	
		}
 
		$im = @imagecreatetruecolor($newWidth,$newHeight);
		imagecopyresampled($im,$originalImage,0,0,0,0,$newWidth,$newHeight,$sizes[0],$sizes[1]);
 
		$type = !isset($specifications['mime']) ? $sizes['mime'] : $specifications['mime'];
		$this->saveImage($im,$outputPath,$type);
 
		// Free up memory		
		imagedestroy($im);
		imagedestroy($originalImage);
	}
 
	private function saveImage($image, $imgname, $type) 
	{
		switch ($type) {
			case 'image/gif' :
				$im = imagegif($image,$imgname);
			break;
			case 'image/jpeg':
				$im = imagejpeg($image,$imgname,100);
			break; 
			case 'image/png':
				$im = imagepng($image,$imgname,9);
		}
		return $im; 
	}
 
	private function loadImage($imgname, $type) 
	{
		switch ($type) {
			case 'image/gif' :
				$im = $this->LoadGif($imgname);
			break;
			case 'image/jpeg':
				$im = $this->LoadJpeg($imgname);
			break; 
			case 'image/png':
				$im = $this->LoadPNG($imgname);
		}
		return $im; 
	}
 
	private function imageerror()
	{
     $im  = imagecreatetruecolor(150, 30); /* Create a black image */
     $bgc = imagecolorallocate($im, 255, 255, 255);
     $tc  = imagecolorallocate($im, 0, 0, 0);
     imagefilledrectangle($im, 0, 0, 150, 30, $bgc);
     /* Output an errmsg */
     imagestring($im, 1, 5, 5, "Error loading $imgname", $tc);
     return $im; 
	}
 
	private function LoadJpeg($imgname)
	{
	   $im =@imagecreatefromjpeg($imgname); /* Attempt to open */
	   if (!$im) { /* See if it failed */
		 	$im = $this->imageerror(); 
	   }
	   return $im;
	}
 
	private function LoadGif ($imgname)
	{
	   $im = @imagecreatefromgif ($imgname); /* Attempt to open */
	   if (!$im) { /* See if it failed */
		 	$im = $this->imageerror(); 
	   }
	   return $im;
	}
 
	private function LoadPNG($imgname)
	{
	   $im = @imagecreatefrompng($imgname); /* Attempt to open */
	   if (!$im) { /* See if it failed */
			 	$im = $this->imageerror(); 	 	
		 }
	  return $im;
	}
}
?>

Example use:

require ('Thumbnailer.php'); 
$tn = new Thumbnailer(dirname(__FILE__).'/../files/images/someimage.jpg');
$thumbOptions = array('maxLength'=>100);
$tn->createThumb($thumbOptions,dirname(__FILE__).'/../files/thumbs/someimage.jpg');