/**

* 改变图片的宽高

*

* @author flynetcn (2009-12-16)

*

* @param string $img_src 原图片的存放地址或url

* @param string $new_img_path 新图片的存放地址

* @param int $new_width 新图片的宽度

* @param int $new_height 新图片的高度

* @return bool 成功true, 失败false

*/

function resize_image($img_src, $new_img_path, $new_width, $new_height)

{

$img_info = @getimagesize($img_src);

if (!$img_info || $new_width < 1 || $new_height < 1 || empty($new_img_path)) {

return false;

}

if (strpos($img_info['mime'], 'jpeg') !== false) {

$pic_obj = imagecreatefromjpeg($img_src);

} else if (strpos($img_info['mime'], 'gif') !== false) {

$pic_obj = imagecreatefromgif($img_src);

} else if (strpos($img_info['mime'], 'png') !== false) {

$pic_obj = imagecreatefrompng($img_src);

} else {

return false;

}

$pic_width = imagesx($pic_obj);

$pic_height = imagesy($pic_obj);

if (function_exists("imagecopyresampled")) {

$new_img = imagecreatetruecolor($new_width,$new_height);

imagecopyresampled($new_img, $pic_obj, 0, 0, 0, 0, $new_width, $new_height, $pic_width, $pic_height);

} else {

$new_img = imagecreate($new_width, $new_height);

imagecopyresized($new_img, $pic_obj, 0, 0, 0, 0, $new_width, $new_height, $pic_width, $pic_height);

}

if (preg_match('~.([^.]+)$~', $new_img_path, $match)) {

$new_type = strtolower($match[1]);

switch ($new_type) {

case 'jpg':

imagejpeg($new_img, $new_img_path);

break;

case 'gif':

imagegif($new_img, $new_img_path);

break;

case 'png':

imagepng($new_img, $new_img_path);

break;

default:

imagejpeg($new_img, $new_img_path);

}

} else {

imagejpeg($new_img, $new_img_path);