PHP implementation of uploading images to generate thumbnails example_PHP tutorial

/**
* Upload images to generate thumbnails
*
* Requires GD2 library support
*
* Parameter new thumbnails('Original address of the image to be thumbnailed', 'Thumbnails' are required during initialization Thumbnail width', 'Thumbnail height', '(optional parameter) Thumbnail saving path');
* If the last parameter is not specified, the thumbnail will be saved in the directory of the original image by default. In the small folder,
* If the small folder does not exist, 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 height values ​​of the image after the image is scaled down
* $size = array ('width'=>'','height'=>'');
* Get the width and height of the image after scaling it down
* $size['width']//Constant ratio The width of the thumbnail
* $size['height']//The height of the proportional thumbnail
*
*/
class thumbnails{

private $imgSrc; //Path of the image
private $saveSrc; / /The saving path of the image, the default is empty
private $canvasWidth; //Width of canvas
private $canvasHeight; //Height of canvas
private $im; //Canvas resource
private $dm ; //Copy the resources returned by 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 $canvasHeight thumbnail The height of the sketch
*/
public function __construct($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 information about the loaded image
*
* Contains length, width, image type
*
* @return array Array containing image length, width, 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 thumbnailing
*
* 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 in the current directory of the large image
*
* If the small directory does not exist, it will be created automatically
*/
 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);
 } 
}