PHP : Auto Resize Image on Upload

Case : you want to resize image on upload
Solution : PHP imagecopyresampled
Script :

if ($_SESSION[username_administrasi] != "" && $_POST[submit] == "Simpan") {
 $cek = cek("select * from ktp where no_ktp = '$no_ktp' and npwp = '$npwp' ");
 if ($cek > 0) {
  alert("Data sudah ada !");
  loncat("../index.php");
 } else { 
  $tmp_filename = $_FILES[file1][tmp_name];
  $filename = $_FILES[file1][name];
  $file = explode(".",$filename);
  $nama_file = $file[0];
  echo $nama_file;
  list($old_width, $old_height, $type, $attr) = getimagesize($tmp_filename);
  if ($type == 1 || $type == 2 || $type == 3) {
   if (($_FILES["file1"]["size"]/1024) > 250) {
    if ($type == 1) {
     $new_image = imagecreatefromgif($tmp_filename);
    } else if ($type == 2) {
     $new_image = imagecreatefromjpeg($tmp_filename);
    } else if ($type == 3) {
     $new_image = imagecreatefrompng($tmp_filename);
    }
    
    echo "
width asli = ".$old_width;
    echo "
height asli = ".$old_height;
    $new_width = 800;
    
    if ($old_width > $old_height) {
     $percentage = ($new_width / $old_width);
    } else {
     $percentage = ($new_width / $old_height);
    }

    $new_width = round($old_width * $percentage);
    $new_height = round($old_height * $percentage);
    
    echo "
width resize = ".$new_width;
    echo "
height resize = ".$new_height;

    echo "
".$_FILES[file1][type];
    echo "
".$_FILES[file1][size];

    
    if (function_exists(imagecreatetruecolor)){
     $resized_img = imagecreatetruecolor($new_width,$new_height);
    }else{
     die("Error: Please make sure you have GD library ver 2+");
    }

    imagecopyresampled($resized_img, $new_image, 0, 0, 0, 0, $new_width, $new_height, $old_width, $old_height);

    if ($type == 1) {
     imagegif($resized_img,"../images/uploaded/tumb_".$nama_file.".gif");
    } else if ($type == 2) {
     imagejpeg($resized_img,"../images/uploaded/tumb_".$nama_file.".jpg");
    } else if ($type == 3) {
     imagepng($resized_img,"../images/uploaded/tumb_".$new_image.".png");
    }
        
    $move = move_uploaded_file($_FILES['file1']['tmp_name'], '../images/uploaded/real_'.$filename); 

    ImageDestroy ($resized_img);
    ImageDestroy ($new_image);

    loncat("../index.php");
   } else {
    
    $move = move_uploaded_file($_FILES['file1']['tmp_name'], '../images/uploaded/real_'.$filename); 
    
    if ($move) {
     alert("Upload sukses.");
    } else {
     alert("Upload gagal.");
    }
    loncat("../index.php");
   }
  } else {
   alert(" Tipe file yang diijinkan : GIF, JPG, JPEG, PNG");
   //loncat("../index.php");
  }
 }
}

Source : http://www.php.net/