Create image thumbnails with PHP

/**
 * Upload images to generate thumbnails
 *
 * Requires GD2 library support
 *
 * Parameters new thumbnails('original address of the image to be thumbnailed', 'width of thumbnail', 'height of thumbnail' are required during initialization ','(optional parameter) Thumbnail saving path');
 * If the last parameter is not specified, the thumbnail will be saved in the small folder in the directory of the original image by default,
 * If small does not exist folder, the small folder will be automatically created
 *
 * After initialization, you need to call the method produce to create thumbnails
 * $thumbnails = new thumbnails(''....);
 * $thumbnails->produce();
 *
 * You can get the relevant information of the original image, width, height, and image mime
 *
 * $thumbnails->getImageWidth(); //int image width
 * $thumbnails->getImageHeight(); / / int Image height
 * $thumbnails->getImageMime(); // string mime of the image
 *
 * $thumbnails->trueSize(); //array This is an array containing the width and sum of the image after scaling it down. Array of height values ​​
 * $size = array('width'=>'','height'=>'');
 * Get the width and height of the image after scaling it
 * $size['width ']//The width of the proportional thumbnail
 * $size['height']//The height of the proportional thumbnail
 *
*/
class thumbnails{

 private $imgSrc; //Picture path
 private $saveSrc; //Picture saving path, default is empty
 private $ canvasWidth; //The width of the canvas
 private $canvasHeight; //The height of the canvas
 private $im; //Canvas resources
 private $dm; //Resources returned by copying the image

 /**
 * Initialize the class and load related settings
 *
 * @param $imgSrc The path of the image that needs to be thumbnailed
 * @param $canvasWidth The width of the thumbnail
 * @param $canvasHeight The height of the thumbnail
*/
 public function __construct($imgSrc,$canvasWidth,$canvasHeight,$saveSrc=null)
 {
 $this->imgSrc = $imgSrc;
 $this->canvasWidth = $canvasWidth;
 $this->canvasHeight = $ canvasHeight;
 $this->saveSrc = $saveSrc;
 }

 /**
 * Generate thumbnails
*/
 public function produce()
 {
 $this->createCanvas();
 $this->judgeImage ();
 $this->copyImage();
 $this->headerImage();
 }

 /**
 * Get the information of the loaded image
 *
 * Contains the length, width, and image type
 *
 * @return array An array containing the image length, width, and mime
*/
 private function getImageInfo()
 {
 return getimagesize($this- >imgSrc);
 }

 /**
 * Get the length of the image
 *
 * @return int The width of the image
*/
 public function getImageWidth()
 {
 $imageInfo = $this->getImageInfo();
 return $imageInfo['0'];
 }

 /**
 * Get the height of the image
 *
 * @return int The height of the image
*/
 public function getImageHeight()
 {
 $imageInfo = $this->getImageInfo();
 return $imageInfo['1'];
 }

 /**
 * Get the type of image
 *
 * @return the mime value of the image
*/
 public function getImageMime()
 {
 $imageInfo = $this->getImageInfo();
 return $imageInfo['mime'];
 }

 /**
 * Create canvas
 *
 * At the same time, put the created canvas resource into the attribute $this->im
*/
 private function createCanvas ()
 {
 $size = $this->trueSize();
 $this->im = imagecreatetruecolor($size['width'],$size['height']);
 }

 /* *
 * Determine the mime value of the image and determine the function to use
 *
 * At the same time, put the created image resource into $this->dm
*/
 private function judgeImage()
 {
 $mime = $this->getImageMime();
 switch ($mime)
 {
 case 'image/png':$dm = imagecreatefrompng($this ->imgSrc);
 break;

 case 'image/gif':$dm = imagecreatefromgif($this->imgSrc);
 break;

 case 'image/jpg':$dm = imagecreatefromjpeg($this ->imgSrc);
 break;

 case 'image/jpeg':$dm = imagecreatefromgjpeg($this->imgSrc);
 break;
 }
 $this->dm = $dm;
 }

	/**
 * Determine the width and height of the image after being reduced
 *
 * This width and height are also used as the size of the canvas
 *
 * @return array The size of the image after being reduced in equal proportions
*/
	public function trueSize()
	{
		$proportionW = $this->getImageWidth() / $this->canvasWidth;
		$proportionH = $this->getImageHeight() / $this->canvasHeight;

		if( ($this->getImageWidth() < $this->canvasWidth) && ($this->getImageHeight() < $this->canvasHeight) )
		{
			$trueSize = array('width'=>$this->getImageWidth(),'height'=>$this->getImageHeight());
		}
		elseif($proportionW >= $proportionH)
		{
			$trueSize = array('width'=>$this->canvasWidth,'height'=>$this->getImageHeight() / $proportionW);
		}
		else
		{
			$trueSize = array('width'=>$this->getImageWidth() / $proportionH,'height'=>$this->canvasHeight);
		}
		return $trueSize;
	}

	/**
 * Copy the image to a new canvas
 *
 * The image will be scaled proportionally and will not be deformed
*/
	private function copyImage()
	{
		$size = $this->trueSize();
		imagecopyresized($this->im, $this->dm , 0 , 0 , 0 , 0 , $size['width'] , $size['height'] , $this->getImageWidth() , $this->getImageheight());
	}

	/**
 * Export the image
 *
 * The name of the image is the same as the original image name by default
 *
 * The path is the small directory under the current directory of the large image
 *
 * If the small directory does not exist, it will be automatically created
*/
	public function headerImage()
	{
		$position = strrpos($this->imgSrc,'/');
		$imageName = substr($this->imgSrc,($position + 1));
		if($this->saveSrc)
		{
			$imageFlode = $this->saveSrc.'/';
		}
		else
		{
			$imageFlode = substr($this->imgSrc,0,$position).'/small/';
		}
		if(!file_exists($imageFlode))
		{
			mkdir($imageFlode);
		}
		$saveSrc = $imageFlode.$imageName;
		imagejpeg($this->im,$saveSrc);
	}
}