Add text watermark php code to existing images

The php library adds text watermarks to existing images. The code is not very complete. Welcome to give us your advice! The code is as follows:

/*PHP picture plus text watermark library

 QQ:3697578482 Sad Song

 This class library currently only supports text watermarks, the location is the lower right corner, and the color is random

 Calling method:
 1. Introduce the class library at the top of the file that needs to be watermarked:
 include_once 'imageClass.php';
 2. Declare a new class:
 $tpl=new image_fu;
 3. Provide parameters for the image watermark:
 $tpl->img(picture path, watermark text, font path, font size, font angle);
 For example: $tpl->img('abc.jpg','This is watermark text','ziti.ttf ',30,0)

*/

 class image_fu{

 private $image;
 private $img_info;
 private $img_width;
 private $img_height;
 private $img_im;
 private $img_text;
 private $img_ttf ='';
 private $img_new;
 private $img_text_size;
 private $img_jd;

 function img($img='',$txt='',$ttf='',$size=12,$jiaodu= 0){
 if(isset($img)&&file_exists($img)){//Check whether the image exists
 $this->image =$img;
 $this->img_text=$txt;
 $this- >img_text_size=$size;
 $this->img_jd=$jiaodu;
 if(file_exists($ttf)){
 $this->img_ttf=$ttf;
 }else{
 exit('Font file: '.$ttf.' does not exist! ');
 }
 $this->imgyesno();
 }else{
 exit('Image file:'.$img.' does not exist');
 }
 }

 private function imgyesno(){

 $this->img_info =getimagesize($this->image);
 $this->img_width =$this->img_info[0];//image width
 $this->img_height=$this->img_info[1];//Picture height

 //Detect picture type
 switch($this->img_info[2]){
 case 1:$this-> ;img_im = imagecreatefromgif($this->image);break;
 case 2:$this->img_im = imagecreatefromjpeg($this->image);break;
 case 3:$this->img_im = imagecreatefrompng ($this->image);break;
 default:exit('The image format does not support watermarks');
 }

 $this->img_text();
 }

 private function img_text(){

 imagealphablending($this->img_im,true);

 //Set color
 $color=imagecolorallocate($this->img_im,rand(0,255),rand(0,255),rand(0,255));
 $ txt_height=$this->img_text_size;
 $txt_jiaodu=$this->img_jd;
 $ttf_im=imagettfbbox($txt_height,$txt_jiaodu,$this->img_ttf,$this->img_text);
 $w = $ttf_im[2] - $ttf_im[6];
 $h = $ttf_im[3] - $ttf_im[7];
 //$w = $ttf_im[7];
 //$h = $ttf_im[ 8];

 unset($ttf_im);

 $txt_y =$this->img_height-$h;
 $txt_x =$this->img_width-$w;
 //$txt_y =0;
 / /$txt_x =0;

 $this->img_new=@imagettftext($this->img_im,$txt_height,$txt_jiaodu,$txt_x,$txt_y,$color,$this->img_ttf,$this- >img_text);

 @unlink($this->image);//Delete the image
 switch($this->img_info[2]) {//Get the format of the background image
 case 1:imagegif($ this->img_im,$this->image);break;
 case 2:imagejpeg($this->img_im,$this->image);break;
 case 3:imagepng($this-> img_im,$this->image);break;
 default: exit('Watermark image failed');
 }

 }

 //Display image
 function img_show(){echo '';}

 //Release memory
 private function img_nothing(){
 unset ($this->img_info);
 imagedestroy($this->img_im);
 }

 }

?>

php