一个超级强大的图片加水印的类(4)

                break 1; 

            case 2 : 

                $this -> water_im = imagecreatefromjpeg($this -> waterImg); 

                break 1; 

            case 1 : 

                $this -> water_im = imagecreatefromgif($this -> waterImg); 

                break 1; 

            default : 

                echo '源图片文件'. $this -> srcImg .'格式不正确，目前本函数只支持PNG、JPEG、GIF图片水印功能'; 

                exit(); 

        } 

    } 

    /**

     * 水印位置算法   

     */ 

    private function waterpos () 

    {  

        switch ($this -> pos) { 

            case 0 : //随机位置    

                $this -> x = rand(0, $this -> srcImg_info[0] - $this -> waterImg_info[0]); 

                $this -> y = rand(0, $this -> srcImg_info[1] - $this -> waterImg_info[1]); 

                break 1; 

            case 1 : //上左    

                $this -> x = 20; 

                $this -> y = 20; 

                break 1; 

            case 2 : //上中    

                $this -> x = ($this -> srcImg_info[0] - $this -> waterImg_info[0]) / 2;