$type_arr = array(1=>'gif', 2=>'jpeg', 3=>'png');

     //获取图片信息

     list($width, $height, $type) = getimagesize($filename);

     //创建一个画布

     $createFun = 'imagecreatefrom' . $type_arr[$type];

     $im = $createFun($f1);

     //保存图片

     $saveFun = 'image' . $type_arr[$type];

     $saveFun($dst, $f2);

     //销毁图片

     imagedestroy($im);    imagedestroy($dst);

 /**

      * 生成缩略图

      * @param $f1   源图片

      * @param $w    缩略图宽度

      * @param $h    缩略图高度

      * @param string $f2 缩略图

      */

     function imgThumb($f1, $w, $h, $f2=''){

         $type_arr = array(1=>'gif', 2=>'jpeg', 3=>'png');

         //获取图片信息

         list($width, $height, $type) = getimagesize($f1);

         //1. 创建画布

         $createFun = 'imagecreatefrom' . $type_arr[$type];

         $src = $createFun($f1);

         $dst = imagecreatetruecolor($w, $h);    //创建空白画布

         //2. 复制图片

         imagecopyresampled($dst, $src, 0, 0, 0, 0, $w, $h, $width, $height);

         //3. 保存图片并销毁画布

         if(empty($f2)) $f2 = $f1;

         $saveFun = 'image' . $type_arr[$type];

         $saveFun($dst, $f2);

         imagedestroy($src);

         imagedestroy($dst);

     }

     /**

      * 给图片添加水印

      * @param $f1   源图片

      * @param $f2   水印图片

      * @param int $coord 坐标，用数字表示，1左上角2右上角3左下角4右下角5上下居中6左右居中7全居中

      * @param string $f3 目标图片

      */

     function imgWater($f1, $f2, $coord=1, $f3=''){

         $type_arr = array(1=>'gif', 2=>'jpeg', 3=>'png');

         //获取图片信息

         list($w1, $h1, $t1) = getimagesize($f1);

         list($w2, $h2, $t2) = getimagesize($f2);

         //1. 创建画布

         $createFun = 'imagecreatefrom' . $type_arr[$t1];

         $im = $createFun($f1);

         $createFun = 'imagecreatefrom' . $type_arr[$t2];

         $waterIm = $createFun($f2);

         //2. 图片复制到另一张图片上

         $px = 0; $py=0;

         switch($coord){

             case 1 :break;

             case 2 :

                 $px = $w1-$w2;

             break;

             case 3 :

                 $py = $h1-$h2;

             break;

             case 4:

                 $px = $w1-$w2;    $py=$h1-$h2;

             break;

             case 5:

                 $py=($h1-$h2)/2;

             break;

             case 6:

                 $px = ($w1-$w2)/2;

             break;

             case 7:

                 $px = ($w1-$w2)/2;    $py=($h1-$h2)/2;

             break;

         }

         imagecopy($im, $waterIm, $px, $py, 0, 0, $w2, $h2);

         //3. 保存图片并销毁画布

         if(empty($f3)) $f3 = $f1;

         $saveFun = 'image' . $type_arr[$t1];

         $saveFun($im, $f3);

         imagedestroy($im);

         imagedestroy($waterIm);

     }

     /**

      * 给图片添加文字

      * @param $f    源图片

      * @param $text 文字

      * @param string $fc    文字颜色

      * @param int $px   文字x坐标

      * @param int $py   文字y坐标

      * @param int $fs   文字字体，1,2,3,4,5表示内置字体

      */

     function imgText($f, $text, $fc='#F00', $px=0, $py=0, $fs=5){

         $type_arr = array(1=>'gif', 2=>'jpeg', 3=>'png');

         //获取图片信息

         list($width, $height, $type) = getimagesize($f);

         //1. 创建画布

         $createFun = 'imagecreatefrom' . $type_arr[$type];

         $im = $createFun($f);

         //2. 图片操作

         //获取颜色

         list($r, $g, $b) = rgbtodec($fc);

         $color = imagecolorallocate($im, $r, $g, $b);

         //计算位置(默认居中)

         if(empty($px) || empty($py)){

             $px = ($width-imagefontwidth($fs) * strlen($text))/2;

             $py = ($height-imagefontheight($fs))/2;

         }

         //写入字符

         imagestring($im, $fs, $px, $py, $text, $color);

         //3. 保存图片并销毁画布

         $saveFun = 'image' . $type_arr[$type];

         $saveFun($im, $f);

         imagedestroy($im);

     }

     //rgb值转换十进制

     function rgbtodec($str){

         $str = str_replace('#', '', $str);

         if(strlen($str)>4){

             $r = substr($str, 0, 2);

             $g = substr($str, 2, 2);

             $b = substr($str, 4, 2);

         }else{

             $r = substr($str, 0, 1); $r .= $r;

             $g = substr($str, 1, 1); $g .= $g;

             $b = substr($str, 2, 1); $b .= $b;

         }

         return array(hexdec($r), hexdec($g), hexdec($b));

     }