简单的php给图片加水印类_php怎么给body加背景图

   目前支持三种图片格式 png , gif , jpeg 

class image_str
  {
      private $img_src;      //图片路径 eg: 'logo.png'
      
      private $img_info_type;     //construcr    type : string
      private $font_size;         // ...  type : int
      
      private $the_image;         //图像标识符
 
      private $x;                 // width    int
      private $y;                 // height   int
      
      function  __construct($src)
      { 
          $this->img_src = $src;
          
          $img_info = getimagesize($this->img_src);
          
          $this->x = $img_info[0];
          $this->y = $img_info[1];
          
          $this->img_info_type = $img_info['mime'];
          
          $this->font_size = 2;
      }
      
      function get_info()
      {
          echo  $this->img_info_type;
      }
      
      public function select()
      {
           switch ($this->img_info_type)
           {
               case 'image/png':
                    $this->the_image = imagecreatefrompng($this->img_src);
                    break;
               case 'image/gif':
                    $this->the_image = imagecreatefromgif($this->img_src);
                    break;     
               case 'image/jpeg':
                    $this->the_image = imagecreatefromjpeg($this->img_src);
                    break;
               default :
                    $this->image_error(); 
                          
           }   
           $this->image(); 
      }
      
      private function image()     // main function
      {
          
          if(! $this->the_image )
              {
               $this->the_image = imagecreate(200,300);
               $bg = imagecolorallocate($this->the_image,255,0,0);
              }
              
          $color_str = imagecolorallocate($this->the_image,255,255,255);
          
          imagestring( $this->the_image, $this->font_size, 15, $this->y - 20, "hello,world", $color_str );
      }
      
      public function get_image()
      {
           header('Content-type:'.$this->img_info_type);
           imagepng($this->the_image); 
      }
  }
  
   
 
    $image = new image_str('logo.png');
    $image->select();
    $image->get_image();
    $image->get_info();

  我不清楚为毛我把 getinfo()的调用放在select()之下的时候就500错误。

  不过无关紧要，get_info()仅是用来测试的。

  好吧，就到这，这很简单