要使用PHP生成图片缩略图,要保证你的PHP服务器安装了GD2图形库 使用一个类生成图片的缩略图

1.使用方法

$resizeimage = new resizeimage("图片源文件地址", "200", "100", "0","缩略图地址");//就只用上面的一句话,就能生成缩略图,其中,源文件和缩略图地址可以相同,200,100分别代表宽和高

2. 缩略图类代码

//使用如下类就可以生成图片缩略图, <?phpclass 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;  //临时创建的图象  var $im;   function resizeimage($img, $wid, $hei,$c,$dstpath)  {    $this->srcimg = $img;    $this->resize_width = $wid;    $this->resize_height = $hei;    $this->cut = $c;    //图片的类型  $this->type = strtolower(substr(strrchr($this->srcimg,"."),1));     //初始化图象    $this->initi_img();    //目标图象地址    $this -> dst_img($dstpath);    //--    $this->width = imagesx($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), $this->height);        ImageJpeg ($newimg,$this->dstimg);      }      if($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)/$resize_ratio));        ImageJpeg ($newimg,$this->dstimg);      }    }    else    //不裁图    {      if($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,$this->dstimg);      }      if($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,$this->dstimg);      }    }  }  //初始化图象  function initi_img()  {    if($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);    }  }  //图象目标地址  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;  }}?>