public static function output(&$image, $type = 'png', $filename = null, $quality = 100)
{
$type == 'jpg' && ($type = 'jpeg');
$imageFun = "image{$type}";
if (is_null($filename)) {
//输出到浏览器
header("Content-type: image/{$type}");
$type == 'jpeg' ? $imageFun($image, null, $quality) : $imageFun($image);
} else {
//保存到文件
$type == 'jpeg' ? $imageFun($image, $filename, $quality) : $imageFun($image, $filename);
}
imagedestroy($image);
exit;
}