Introduction

    static void Example()
    {
      // Select a source folder
      AbstractFolder folder = new DiskFolder( @"DataFolderToZip" );

      // Select a zip file
      AbstractFile zipFile = new DiskFile( @"ZipChangeMetadataInEvent.zip" );

      // If the zip file already exists
      if( zipFile.Exists )
      {
        // Delete it
        zipFile.Delete();
      }

      // Wrap a logical zip archive around the zip file
      ZipArchive zip = new ZipArchive( zipFile );

      // Create events
      ZipEvents zipEvents = new ZipEvents();

      // Assign our method to handle the event where an item has completed processing
      zipEvents.ItemCompletion += new ItemProgressionEventHandler( OnItemCompletion );

      // Start a zip batch operation
      using( AutoBatchUpdate update = new AutoBatchUpdate( zip ) )
      {
        /* We get the current date/time once here to avoid getting it on each zipped item. It could hinder performance */

        // Get the current date/time
        DateTime now = DateTime.Now;

        // Zip the source files, hooking in events and a maximum allowable date/time as user data
        folder.CopyFilesTo( zipEvents, now, zip, true, true );
      }
    }

    static void OnItemCompletion( object sender, ItemProgressionEventArgs e )
    {
      /* At this point, the item has been zipped but it is still safe and efficient to update its metadata like
       * the last write date/time. Headers will simply be updated. The item's data will not need to be compressed
       * again */

      // Get the maximum allowable date/time for our zipped item
      DateTime maxAllowedDateTime = ( DateTime ) e.UserData;

      // If the zipped item has a last write date/time that is unacceptable to us
      if( e.TargetItem.LastWriteDateTime > maxAllowedDateTime )
      e{
        // Express the item as a ZippedFile
        ZippedFile zippedFile = ( ZippedFile ) e.TargetItem;

        /* The only situation where changing the last write date/time will not work if it the item was
         * zipped with "Zip Compatible encryption". This is a deprecated, not secure algorithm and should not be
         * used in new code anyway. Since zipping is under our control here, it will not happen. */
        System.Diagnostics.Debug.Assert( !( zippedFile.Encrypted && zippedFile.EncryptionMethod == EncryptionMethod.Compatible ) );

        // Update the zipped item last write date/time to our acceptable value
        zippedFile.LastWriteDateTime = maxAllowedDateTime;

        /* TODO: Other properties can be changed here too */
//         zippedFile.CreationDateTime = myDate;
//         zippedFile.LastAccessDateTime = myDate;
//         zippedFile.Comment = "My comment";
//         zippedFile.Name = "My name";
//         zippedFile.ExtraHeaders = myExtraHeaders;
//         zippedFile.EncryptionPassword = "My password";
//         zippedFile.EncryptionMethod = myMethod;
//         zippedFile.EncryptionStrength = myStrenngth;
//         zippedFile.CompressionMethod = myCompressionMethod;
//         zippedFile.CompressionLevel = myCompressionLevel;
      }
    }