create_zip_folders.php

<?php

//Start of class
class xZip {

  public function __construct() {}
  public function __destruct() {}

  public function zip($source = NULL, $destination = "./",$max_size_of_1_zip_archive) {
    if (!$destination || trim($destination) == "") {
      $destination = "./";
    }
    $input = array();
    $this->_rglobRead($source, $input);
    //$maxinput = count($input);
    //$splitinto = (($maxinput / $limit) > round($maxinput / $limit, 0)) ? round($maxinput / $limit, 0) + 1 : round($maxinput / $limit, 0);
    //Add code to ensure that a max of $max_size_of_1_zip_archive MB are added to zip archive
    $total_number_of_images = sizeof($input);
    echo "Total Number of Images:".$total_number_of_images."\n";
    $current_image_array_counter_position = 0;
    $beginning_image_array_index_for_archive = 0;
    $archive_counter = 0;
    $current_archive_size = 0;
    while($current_image_array_counter_position < $total_number_of_images)
    {
      $current_image_file_size = filesize($input[$current_image_array_counter_position]);
      $current_image_file_size = ($current_image_file_size/1024);//to convert from bytes to Kilobytes.

      /*echo "beginning_image_array_counter_position value: ".$beginning_image_array_index_for_archive."\n";
      echo "current_image_array_counter_position value: ".$current_image_array_counter_position."\n";
      */
      //sleep(1);
      if(($current_archive_size + ($current_image_file_size) ) > ($max_size_of_1_zip_archive*1024))
      {
        $this->_zip(array_slice($input, $beginning_image_array_index_for_archive, ($current_image_array_counter_position-$beginning_image_array_index_for_archive), true), $archive_counter++, $destination);
        $beginning_image_array_index_for_archive = $current_image_array_counter_position;
        echo "Archive Number: ".($archive_counter)."\n";
        echo "Finished Archive Size: ".$current_archive_size."\n\n";
        $current_archive_size = 0;
      }
      else
      {
        $current_archive_size += ($current_image_file_size);
        $current_image_array_counter_position++;
        echo "Current Image File Size: ".$current_image_file_size."\n";
        echo "Current Archive Size: ".$current_archive_size."\n";
        echo "Number of Files in Archive: ".($current_image_array_counter_position-$beginning_image_array_index_for_archive)."\n";
      }
    }

    if($current_archive_size > 0)
    {
      $this->_zip(array_slice($input, $beginning_image_array_index_for_archive, ($current_image_array_counter_position-$beginning_image_array_index_for_archive), true), $archive_counter++, $destination);
      $beginning_image_array_index_for_archive = $current_image_array_counter_position;
      echo "Archive Number: ".($archive_counter)."\n";
      echo "Finished Archive Size: ".$current_archive_size."\n";
    }

    //echo "size of input array: ".(sizeof($input))."\n";
    //echo "value of begining of array index: ".$beginning_image_array_index_for_archive."\n";
    //echo "value of current of array index: ".$current_image_array_counter_position."\n";
    unset($input);
    return;
  }
  public function unzip($source, $destination) {
    @mkdir($destination, 0777, true);

    foreach ((array) glob($source . "/*.zip") as $key => $value) {
      $zip = new ZipArchive;
      if ($zip->open(str_replace("//", "/", $value)) === true) {
        $zip->extractTo($destination);
        $zip->close();
      }
    }
  }

  private function _zip($array, $part, $destination) {
    $zip = new ZipArchive;
    @mkdir($destination, 0777, true);

    if ($zip->open(str_replace("//", "/", "{$destination}/partz{$part}.zip"), ZipArchive::CREATE)) {
      foreach ((array) $array as $key => $value) {
        $value_of_filename_in_ziparchive = "";
        $value_of_filename_in_ziparchive = substr($value, strrpos($value, '/') + 1);
        //echo (sizeof($array))." ".$part." ".$value_of_filename_in_ziparchive."\n";
        $zip->addFile($value, $value_of_filename_in_ziparchive);
      }
      $zip->close();
    }
  }

  private function _rglobRead($source, &$array = array()) {
    if (!$source || trim($source) == "") {
      $source = ".";
    }
    foreach ((array) glob($source . "/*/") as $key => $value) {
      $this->_rglobRead(str_replace("//", "/", $value), $array);
    }

    foreach ((array) glob($source . "*.*") as $key => $value) {
      $array[] = str_replace("//", "/", $value);
    }
  }
}
//End of Class

//Parent process code:
//Defining session specific variables below:
$max_size_of_1_zip_archive = 5; //This value is in MBs.
$input_path_of_image_files = "~/source_pictures/";
$output_path_of_zip_archives = "~/destination_archives/";
//Invoking class xZip:
$zip = new xZip();
$zip->zip($input_path_of_image_files, $output_path_of_zip_archives,$max_size_of_1_zip_archive);
?>

Modified from http://php.net/manual/en/class.ziparchive.php