该如何去调用这个类

/*

图片处理类：缩略，裁剪，圆角，倾斜

*/

class resizeimage

{

   //图片类型

   var $type;

   //实际宽度

   var $width;

   //实际高度

   var $height;

   //改变后的宽度

   var $resize_width;

   //改变后的高度

   var $resize_height;

   //是否裁图

   var $cut;

   //源图象

   var $srcimg;

   //目标图象地址

   var $dstimg;

   //圆角源

   var $corner;

   var $im;

function resizeimage($img, $corner, $wid, $hei,$c, $corner_radius, $angle)

   {

       $this->srcimg = $img;

    $this->corner = $corner;

       $this->resize_width = $wid;

       $this->resize_height = $hei;

       $this->cut = $c;

    $this->corner_radius = $corner_radius;

    $this->angle = $angle;

       //图片的类型

       $this->type = substr(strrchr($this->srcimg,"."),1);

       //初始化图象

       $this->initi_img();

       //目标图象地址

       $this -> dst_img();

       //--

       $this->width = imagesx($this->im);

       $this->height = imagesy($this->im);

       //生成图象

       $this->newimg();

       ImageDestroy ($this->im);

   }

   function newimg()

   {

       //改变后的图象的比例

       $resize_ratio = ($this->resize_width)/($this->resize_height);

       //实际图象的比例

       $ratio = ($this->width)/($this->height);

       if(($this->cut)=="1")

       //裁图

       {

           if($ratio>=$resize_ratio)

           //高度优先

           {

               $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);

               imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height);

      $tmp = $this->rounded_corner($newimg,$this->resize_width);

               imagepng ($tmp,$this->dstimg);

           }

           if($ratio<$resize_ratio)

           //宽度优先

           {

               $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);

               imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width)/$resize_ratio));

      $tmp = $this->rounded_corner($newimg);

               imagepng ($tmp,$this->dstimg);

           }

       }

       else

       //不裁图

       {

           if($ratio>=$resize_ratio)

           {

               $newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio);

               imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $this->width, $this->height);

               ImageJpeg ($newimg,$this->dstimg);

           }