PHP image thumbnail generation code (supports png transparency)

/*
 * desc: Resize Image(png, jpg, gif)
*/
class ResizeImage {
//Image type
private $type;
// Actual width
private $width;
//Actual height
private $height;
//Changed width
private $resize_width;
//Changed height
private $resize_height;
//Whether to crop the image
private $ cut;
//Source image
private $srcimg;
//Destination image address
private $dstimg;
//Temporarily created image
private $im;
function __construct ($imgPath, $width, $height, $isCut, $savePath) {
$this->srcimg = $imgPath;
$this->resize_width = $width;
$this->resize_height = $height;
$this->cut = $isCut;
//Type of picture
$this->type = strtolower(substr(strrchr($this->srcimg,"." ),1));
//Initialize image
$this->initi_img();
//Target image address
$this -> dst_img($savePath);
//--
$this->width = imagesx($this->im);
$this->height = imagesy($this->im);
//Generate image
$this ->newimg();
ImageDestroy ($this->im);
}
private function newimg() {
//The ratio of the changed image
$resize_ratio = ($this->resize_width)/($this->resize_height);
//The ratio of the actual image
$ratio = ($this->width)/($this->height);
if ($this->cut) {
//Cut image
$newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);
if($this->type=="png") {
imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0, 0, 127));
}
if($ratio>=$resize_ratio) {
//High priority
imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height) ;
} else {
//Width first
imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this-> width, (($this->width)/$resize_ratio));
}
} else {
//Do not crop the image
if($ratio>=$resize_ratio) {
$newimg = imagecreatetruecolor($this-> ;resize_width,($this->resize_width)/$ratio);
if($this->type=="png") {
imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0 , 0, 127));
}
imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $ this->width, $this->height);
} else {
$newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height);
if($this- >type=="png") {
imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0, 0, 127));
}
imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height);
}
}
if($ this->type=="png") {
imagesavealpha($newimg, true);
imagepng ($newimg,$this->dstimg);
} else {
imagejpeg ($newimg,$this-> dstimg);
}
}
//Initialize image
private function initi_img() {
if($this->type=="jpg") {
$this-> ;im = imagecreatefromjpeg($this->srcimg);
}
if($this->type=="gif") {
$this->im = imagecreatefromgif($this->srcimg);
 }
if($this->type=="png") {
$this->im = imagecreatefrompng($this->srcimg);
}
}
/ /Image target address
private function dst_img($dstpath) {
$full_length = strlen($this->srcimg);
$type_length = strlen($this->type) ;
$name_length = $full_length-$type_length;

$name = substr($this->srcimg,0,$name_length-1);
$this->dstimg = $dstpath;
}
}
?>

When using it, just call the constructor of the class directly. The constructor: $resizeimage = new resizeimage($imgPath, $width, $height, $isCut, $savePath);

Parameters $imgPath: original image address $width: thumbnail width $height: Thumbnail height $isCut: Whether to crop, bool value $savePath: thumbnail address (can be the same as the original image address)

Example:

include "ResizeImage.php";
//jpg
$jpgResize = new ResizeImage("img/test_1920_1200.jpg" , 320, 240, false, "img/test_320_240.jpg");
//png
$pngResize = new ResizeImage("img/test_1024_746.png", 320, 240, false, "img/test_320_240.png");
?>

Effect: