Php 调整上载的图像文件大小

我想调整用户上传到服务器的图像大小。我希望它是200x200像素。目前，这里是我正在使用的代码。它可以正常上传，但不会将图像大小调整为200x200。还是有办法缩小文件大小

// make a note of the current working directory, relative to root.
$directory_self = str_replace(basename($_SERVER['PHP_SELF']), '', $_SERVER['PHP_SELF']);

// make a note of the directory that will recieve the uploaded files
$uploadsDirectory = $_SERVER['DOCUMENT_ROOT'] . $directory_self . 'uploaded_files/';

// make a note of the location of the upload form in case we need it
$uploadForm = 'http://' . $_SERVER['HTTP_HOST'] . $directory_self . 'upload.form.php';

// make a note of the location of the success page
$uploadSuccess = 'http://' . $_SERVER['HTTP_HOST'] . $directory_self .     'upload.success.php';

// name of the fieldname used for the file in the HTML form
$fieldname = 'file';


// Now let's deal with the upload

// possible PHP upload errors
$errors = array(1 => 'php.ini max file size exceeded', 
            2 => 'html form max file size exceeded', 
            3 => 'file upload was only partial', 
            4 => 'no file was attached');

// check the upload form was actually submitted else print form
isset($_POST['submit'])
or error('the upload form is neaded', $uploadForm);

// check for standard uploading errors
($_FILES[$fieldname]['error'] == 0)
or error($errors[$_FILES[$fieldname]['error']], $uploadForm);

// check that the file we are working on really was an HTTP upload
@is_uploaded_file($_FILES[$fieldname]['tmp_name'])
or error('not an HTTP upload', $uploadForm);

// validation... since this is an image upload script we 
// should run a check to make sure the upload is an image
@getimagesize($_FILES[$fieldname]['tmp_name'])
or error('only image uploads are allowed', $uploadForm);

// make a unique filename for the uploaded file and check it is 
// not taken... if it is keep trying until we find a vacant one
//$now = time();

while(file_exists($uploadFilename = $uploadsDirectory.$fb_id.'-'.$_FILES[$fieldname]    ['name']))
{
//$now++;
}

// now let's move the file to its final and allocate it with the new filename
@move_uploaded_file($_FILES[$fieldname]['tmp_name'], $uploadFilename)
or error('receiving directory insuffiecient permission', $uploadForm);

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切勿收缩文件，否则会对图片造成不必要的损坏。而是尝试使用图像函数等新的缩放尺寸重新创建图像。它提供了重建和调整大小所需的一切。此外，您也可以使用Imagick库，它具有更高级的功能

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当你找到合适的工作时，也要尝试接受答案，如果你的接受率足够公平，它会让人们回答你更多的问题。

那么你想让我们为你编写代码吗？我给出的代码只用于上传。如何通过添加调整大小功能来增强它？对不起，我是phpso的新成员，您是新成员，希望我们为您完成工作。喂，我对盖房子是个新手，你能帮我盖一栋吗？