$resizeimage = new resizeimage("圖片源文件地址", "200", "100", "0","縮略圖地址");
//就只用上面的一句話,就能生成縮略圖,其中,源文件和縮略圖地址可以相同,200,100分別代表寬和高

//使用如下類就可以生成圖片縮略圖,
 
<?php
class resizeimage
{
  //圖片類型
  var $type;
  //實際寬度
  var $width;
  //實際高度
  var $height;
  //改變后的寬度
  var $resize_width;
  //改變后的高度
  var $resize_height;
  //是否裁圖
  var $cut;
  //源圖象
  var $srcimg;
  //目標圖象地址
  var $dstimg;
  //臨時創(chuàng)立的圖象
  var $im;
 
  function resizeimage($img, $wid, $hei,$c,$dstpath)
  {
    $this->srcimg = $img;
    $this->resize_width = $wid;
    $this->resize_height = $hei;
    $this->cut = $c;
    //圖片的類型
  
$this->type = strtolower(substr(strrchr($this->srcimg,"."),1));
 
    //初始化圖象
    $this->initi_img();
    //目標圖象地址
    $this -> dst_img($dstpath);
    //--
    $this->width = imagesx($this->im);
    $this->height = imagesy($this->im);
    //生成圖象
    $this->newimg();
    ImageDestroy ($this->im);
  }
  function newimg()
  {
    //改變后的圖象的比例
    $resize_ratio = ($this->resize_width)/($this->resize_height);
    //實際圖象的比例
    $ratio = ($this->width)/($this->height);
    if(($this->cut)=="1")
    //裁圖
    {
      if($ratio>=$resize_ratio)
      //高度優(yōu)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), $this->height);
        ImageJpeg ($newimg,$this->dstimg);
      }
      if($ratio<$resize_ratio)
      //寬度優(yōu)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)/$resize_ratio));
        ImageJpeg ($newimg,$this->dstimg);
      }
    }
    else
    //不裁圖
    {
      if($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,$this->dstimg);
      }
      if($ratio<$resize_ratio)
      {
        $newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height);
        imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height);
        ImageJpeg ($newimg,$this->dstimg);
      }
    }
  }
  //初始化圖象
  function initi_img()
  {
    if($this->type=="jpg")
    {
      $this->im = imagecreatefromjpeg($this->srcimg);
    }
    if($this->type=="gif")
    {
      $this->im = imagecreatefromgif($this->srcimg);
    }
    if($this->type=="png")
    {
      $this->im = imagecreatefrompng($this->srcimg);
    }
  }
  //圖象目標地址
  function dst_img($dstpath)
  {
    $full_length = strlen($this->srcimg);
 
    $type_length = strlen($this->type);
    $name_length = $full_length-$type_length;
 
 
    $name     = substr($this->srcimg,0,$name_length-1);
    $this->dstimg = $dstpath;
 
 
//echo $this->dstimg;
  }
}
?>