Base64格式转换成图片文件

<?php
/*
 * base64图片 在服务器生成图片 并返回路径 
 */
header("Access-Control-Allow-Origin: *");
header('Content-type:text/html;charset=utf-8');
$base64_image_content = $_POST['content'];
//匹配出图片的格式
if (preg_match('/^(data:\s*image\/(\w+);base64,)/', $base64_image_content, $result)){
    $type = $result[2];
    $dir = '../upload/screen_images/' . date('Y/m/',time());
    if(!file_exists($dir)) {
        mkdir($dir,0777,true);
    }
    $new_file = $dir . uniqid() . ".{$type}";
    if (file_put_contents($new_file, base64_decode(str_replace($result[1], '', $base64_image_content)))){
        $img = 'xxx路径' . ltrim($new_file, ".");
        return $img;
    } else {
        return false;
    }
} else {
    return false;
}
?>