php image processing class (simple and easy to use)

The code is as follows:

<?php  
 class Image {  
     private $path;  
     //构造方法用来对图片所在位置进行初使化  
     function __construct($path="./"){  
     $this->path=rtrim($path, "/")."/";  
     }  
     /* 对图片进行缩放 
      * 
      * 参数$name: 是需要处理的图片名称 
      * 参数$width:是缩放后的宽度 
      * 参数$height:是缩放后的高度 
      * 参数$qz: 是新图片的名称前缀 
      * 返回值:就是缩放后的图片名称，失败则返回false 
      * 
      */  
  function thumb($name, $width, $height, $qz="th_"){  
  //获取图片信息  
  $imgInfo=$this->getInfo($name); //图片的宽度，高度，类型  
  //获取图片资源, 各种类型的图片都可以创建资源 jpg, gif, png  
  $srcImg=$this->getImg($name, $imgInfo);  
  //获取计算图片等比例之后的大小, $size["width"], $size["height"]  
  $size=$this->getNewSize($name, $width, $height, $imgInfo);  
  //获取新的图片资源, 处理一下gif透明背景  
  $newImg=$this->kidOfImage($srcImg, $size, $imgInfo);  
  //另存为一个新的图片，返回新的缩放后的图片名称      
  return $this->createNewImage($newImg, $qz.$name, $imgInfo);    
     }  
      
     private function createNewImage($newImg, $newName, $imgInfo){  
  switch($imgInfo["type"]){  
      case 1://gif  
   $result=imageGif($newImg, $this->path.$newName);  
   break;  
      case 2://jpg  
   $result=imageJPEG($newImg, $this->path.$newName);  
   break;  
      case 3://png  
   $return=imagepng($newImg, $this->path.$newName);  
   break;  
  }  
  imagedestroy($newImg);  
  return $newName;  
     }  
      
     private function kidOfImage($srcImg, $size, $imgInfo){  
  $newImg=imagecreatetruecolor($size["width"], $size["height"]);  
    
  $otsc=imagecolortransparent($srcImg);  
      
  if($otsc >=0 && $otsc <= imagecolorstotal($srcImg)){  
      $tran=imagecolorsforindex($srcImg, $otsc);  
      
      $newt=imagecolorallocate($newImg, $tran["red"], $tran["green"], $tran["blue"]);  
      
      imagefill($newImg, 0, 0, $newt);  
      
      imagecolortransparent($newImg, $newt);  
  }  
      
  imagecopyresized($newImg, $srcImg, 0, 0, 0, 0, $size["width"], $size["height"], $imgInfo["width"], $imgInfo["height"]);  
      
  imagedestroy($srcImg);  
      
  return $newImg;  
     }  
      
     private function getNewSize($name, $width, $height, $imgInfo){  
  $size["width"]=$imgInfo["width"];  
  $size["height"]=$imgInfo["height"];  
      
  //缩放的宽度如果比原图小才重新设置宽度  
  if($width < $imgInfo["width"]){  
      $size["width"]=$width;  
  }  
  //缩放的高度如果比原图小才重新设置高度  
  if($height < $imgInfo["height"]){  
      $size["height"]=$height;  
  }  
      
  //图片等比例缩放的算法  
  if($imgInfo["width"]*$size["width"] > $imgInfo["height"] * $size["height"]){  
      $size["height"]=round($imgInfo["height"]*$size["width"]/$imgInfo["width"]);  
  }else{  
      $size["width"]=round($imgInfo["width"]*$size["height"]/$imgInfo["height"]);  
  }     
  return $size;
     }  
      
     private function getInfo($name){  
  $data=getImageSize($this->path.$name);  
      
  $imageInfo["width"]=$data[0];  
  $imageInfo["height"]=$data[1];  
  $imageInfo["type"]=$data[2];  
      
  return $imageInfo;  
     }  
      
     private function getImg($name, $imgInfo){  
  $srcPic=$this->path.$name;  
      
  switch($imgInfo["type"]){  
      case 1: //gif  
   $img=imagecreatefromgif($srcPic);  
   break;  
      case 2: //jpg  
   $img=imageCreatefromjpeg($srcPic);  
   break;  
      case 3: //png  
   $img=imageCreatefrompng($srcPic);  
   break;  
      default:  
   return false;  
        
  }  
      
  return $img;  
     }  
     /* 功能：为图片加水印图片 
      * 参数$groundName: 背景图片，即需要加水印的图片 
      * 参数$waterName: 水钱图片 
      * 参数#aterPost：水印位置， 10种状态，  
      *  0为随机位置 
      * 
      *  1. 为顶端居左  2. 为顶端居中  3 为顶端居右 
      *  4  为中部居左  5. 为中部居中  6 为中部居右 
      *  7 . 为底端居左 8. 为底端居中， 9. 为底端居右 
      * 
      * 参数$qz : 是加水印后的图片名称前缀 
      * 返回值：就是处理后图片的名称 
      * 
      */  
     function waterMark($groundName, $waterName, $waterPos=0, $qz="wa_"){  
       
  if(file_exists($this->path.$groundName) && file_exists($this->path.$waterName)){  
      $groundInfo=$this->getInfo($groundName);  
      $waterInfo=$this->getInfo($waterName);  
      //水印的位置  
      if(!$pos=$this->position($groundInfo, $waterInfo, $waterPos)){  
   echo "水印不应该比背景图片小！";  
   return;  
      }  
      
      $groundImg=$this->getImg($groundName, $groundInfo);  
      $waterImg=$this->getImg($waterName, $waterInfo);  
      
      $groundImg=$this->copyImage($groundImg, $waterImg, $pos, $waterInfo);  
      
      return $this->createNewImage($groundImg, $qz.$groundName, $groundInfo);  
  }else{  
      echo "图片或水印图片不存在";  
      return false;  
  }  
     }  
      
     private function copyImage($groundImg, $waterImg, $pos, $waterInfo){  
  imagecopy($groundImg, $waterImg, $pos["posX"], $pos["posY"], 0, 0, $waterInfo["width"], $waterInfo["height"]);  
  imagedestroy($waterImg);  
      
  return $groundImg;  
     }  
       
     private function position($groundInfo, $waterInfo, $waterPos){  
  //需要背景比水印图片大  
  if(($groundInfo["width"]< $waterInfo["width"]) ||($groundInfo["height"] < $waterInfo["height"])){  
      return false;  
  }  
      
  switch($waterPos){  
      case 1:  
   $posX=0;  
   $posY=0;  
   break;  
      case 2:  
   $posX=($groundInfo["width"]-$waterInfo["width"])/2;  
   $posY=0;  
   break;  
      case 3:  
   $posX=$groundInfo["width"]-$waterInfo["width"];  
   $posY=0;  
   break;  
      case 4:  
   $posX=0;  
   $posY=($groundInfo["height"]-$waterInfo["height"]) /2;  
   break;  
      case 5:  
   $posX=($groundInfo["width"]-$waterInfo["width"])/2;  
   $posY=($groundInfo["height"]-$waterInfo["height"]) /2;  
   break;  
      case 6:  
   $posX=$groundInfo["width"]-$waterInfo["width"];  
   $posY=($groundInfo["height"]-$waterInfo["height"]) /2;  
   break;  
      case 7:  
   $posX=0;  
   $posY=$groundInfo["height"]-$waterInfo["height"];  
   break;  
      case 8:  
   $posX=($groundInfo["width"]-$waterInfo["width"])/2;  
   $posY=$groundInfo["height"]-$waterInfo["height"];  
   break;  
      case 9:  
   $posX=$groundInfo["width"]-$waterInfo["width"];  
   $posY=$groundInfo["height"]-$waterInfo["height"];  
   break;  
      case 0:  
      default:  
   $posX=rand(0, ($groundInfo["width"]-$waterInfo["width"]));  
   $posY=rand(0, ($groundInfo["height"]-$waterInfo["height"]));  
   break;  
  }  
      
  return array("posX"=>$posX, "posY"=>$posY);  
     }       
 }