Resize Image While Uploading with PHP

On my previous post I was shown an example how to upload file with php and html. It was based on php simple image upload functionality. Today I am going to show you little bit advance of image uploading. Suppose if you run a website and want to allow users to upload image files than you need to think little bit about server's space and bandwidth. For this purpose you need to do some optimization with image files. Image resize while uploading is one of them. All major website do it in the same way. If a user uploads a 5mb image file they resize it in different sizes and store on there server. It helps them to seed up there website and reduce there budget. Now take a look, how we can do it ourself.

Live Demo Download Source
PHP and HTML(index.php)
This file holds the basic of file uploading html markup and simple php upload handler.

<?php
include( 'function.php');
// settings
$max_file_size = 1024*200; // 200kb
$valid_exts = array('jpeg', 'jpg', 'png', 'gif');
// thumbnail sizes
$sizes = array(100 => 100, 150 => 150, 250 => 250);

if ($_SERVER['REQUEST_METHOD'] == 'POST' AND isset($_FILES['image'])) {
  if( $_FILES['image']['size'] < $max_file_size ){
    // get file extension
    $ext = strtolower(pathinfo($_FILES['image']['name'], PATHINFO_EXTENSION));
    if (in_array($ext, $valid_exts)) {
      /* resize image */
      foreach ($sizes as $w => $h) {
        $files[] = resize($w, $h);
      }

    } else {
      $msg = 'Unsupported file';
    }
  } else{
    $msg = 'Please upload image smaller than 200KB';
  }
}
?>
<html>
<head>
  <title>Image resize while uploadin</title>
<head>
<body>
  <!-- file uploading form -->
  <form action="" method="post" enctype="multipart/form-data">
    <label>
      <span>Choose image</span>
      <input type="file" name="image" accept="image/*" />
    </label>
    <input type="submit" value="Upload" />
  </form>
</body>
</html>

Resize Function(function.php):
Resize function is based on PHP GD library.

/**
 * Image resize
 * @param int $width
 * @param int $height
 */
function resize($width, $height){
  /* Get original image x y*/
  list($w, $h) = getimagesize($_FILES['image']['tmp_name']);
  /* calculate new image size with ratio */
  $ratio = max($width/$w, $height/$h);
  $h = ceil($height / $ratio);
  $x = ($w - $width / $ratio) / 2;
  $w = ceil($width / $ratio);
  /* new file name */
  $path = 'uploads/'.$width.'x'.$height.'_'.$_FILES['image']['name'];
  /* read binary data from image file */
  $imgString = file_get_contents($_FILES['image']['tmp_name']);
  /* create image from string */
  $image = imagecreatefromstring($imgString);
  $tmp = imagecreatetruecolor($width, $height);
  imagecopyresampled($tmp, $image,
    0, 0,
    $x, 0,
    $width, $height,
    $w, $h);
  /* Save image */
  switch ($_FILES['image']['type']) {
    case 'image/jpeg':
      imagejpeg($tmp, $path, 100);
      break;
    case 'image/png':
      imagepng($tmp, $path, 0);
      break;
    case 'image/gif':
      imagegif($tmp, $path);
      break;
    default:
      exit;
      break;
  }
  return $path;
  /* cleanup memory */
  imagedestroy($image);
  imagedestroy($tmp);
}