php生成縮略圖

php生成縮略圖，並把它輸出到網頁上，不過需在php文件頭加一句話：header("Content-Type:image/jpg");
代碼如下：

<?php 

  header("Content-Type:image/jpg");
  class resizeImg {
     private $type;
     private $width;
     private $height;
     private $resize_width;
     private $resize_height;
     private $srcimg; //圖片源地址
     private $desimg; //圖片目的地址
     private $img; //新建臨時文件
     private $cut; //判斷是否截圖
     private $name; //文件名

    function __construct($imgpath,$width,$height,$despath,$cut) { //圖片路徑，新寬度，新高度，目的地址，是否裁剪
       $this->srcimg = $imgpath;
       $this->resize_width = $width;
       $this->resize_height = $height;
       $this->cut = $cut;
       $this->type = strtolower(substr(strrchr($this->srcimg,"."),1));
       $this->init_img();
       $this->name_img(); //獲取文件名
       $this->des_img($despath); //將文件放到指定文件
       $this->width = imagesx($this->img); //獲取圖像寬度
       $this->height = imagesy($this->img); //獲取圖像高度
       $this->new_img();
       imagedestroy($this->img);
    }

    function init_img() { //初始化圖像
      if($this->type == "jpg") {
           $this->img = imagecreatefromjpeg($this->srcimg);
     }elseif($this->type == "gif"){
           $this->img = imagecreatefromgif($this->srcimg);
     }
     elseif($this->type == "png") {
           $this->img = imagecreatefrompng($this->srcimg);
     }
     else{
           echo "文件類型不對!!!";
     }
   }
   function des_img($despath) { //圖象目標地址
       $this->desimg = $despath.$this->name.'.'.$this->type; //把完整地址賦給$desimg
   }
   function name_img() {
      $full_length = strlen($this->srcimg);
      $type_length = strlen($this->type);
      $name_length = $full_length-$type_length;
      $this->name = substr($this->srcimg,0,$name_length-1); //獲取文件名
   }
   function new_img() { //新圖像
      $resize_ratio = ($this->resize_width)/($this->resize_height); //新圖像比例
      $ratio = ($this->width)/($this->height); //源圖像比例

      if($this->cut == 1) { //截圖
      if($ratio >= $resize_ratio) {
           $newimg = imagecreatetruecolor($this->resize_width, $this->resize_height);
           imagecopyresampled($newimg, $this->img, 0, 0, 0, 0, $this->resize_width, $this->resize_height, ($this->height)*$resize_ratio, $this->height);
          imagejpeg($newimg,$this->desimg); //把圖片的內容輸出到$this->desimg上
          imagejpeg($newimg); //將圖片輸出到網頁上

    }else {
          $newimg = imagecreatetruecolor($this->resize_width, $this->resize_height);
          imagecopyresampled($newimg, $this->img, 0, 0, 0, 0, $this->resize_width, $this->resize_height, ($this->width)/$resize_ratio, $this->width);

         imagejpeg($newimg,$this->desimg);
         imagejpeg($newimg); ////將圖片輸出到網頁上
     }
   }
   else { //不截圖
      if($ratio >= $resize_ratio) {
         $newimg = imagecreatetruecolor($this->resize_width, ($this->resize_width)/$ratio); 
         imagecopyresampled($newimg, $this->img, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $this->width, $this->height);
         imagejpeg($newimg,$this->desimg);
         imagejpeg($newimg); ////將圖片輸出到網頁上
  }
   else {
         $newimg = imagecreatetruecolor(($this->resize_height)*$ratio, $this->resize_height);
         imagecopyresampled($newimg, $this->img, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height);

         imagejpeg($newimg,$this->desimg);
         imagejpeg($newimg); // //將圖片輸出到網頁上
      }
     }
   } 
 } 

 $resizeimg = new resizeImg("./1.jpg",200,200,"work/",0);
?>