Events

The ZipWriter and ZipReader classes provides events that let you monitor the progress of the Zip archive creation and extraction processes. Three types of events are available, which are described and demonstrated below.

Event	Description
ByteProgression (writing, reading)	Used to access byte progression information when reading or writing a Zip archive. Available in ZipWriter and ZipReader.
InvalidPassword	Used when an invalid password is provided.

The ByteProgression event

The ZipWriter and ZipReader classes both expose a ByteProgression event, which is raised when WriteItemData or ReadItemData is called.

A ZipWriterByteProgressionEventArgs object provides the following properties for use in ZipWriter's ByteProgression event handler:

Property	Description
BytesProcessed	The number of bytes processed of the current file.
ZipItemLocalHeader	The local header of the item currently being processed.

A ZipReaderByteProgressionEventArgs object provides the following properties for use in ZipReader's ByteProgression event handler:

Property	Description
BytesProcessed	The number of bytes processed of the current file.
Percent	The percentage of the current file that has been processed.
UncompressedSize	The uncompressed size of the current file.
ZipItemLocalHeader	The local header of the file currently being processed.

When the compressed/uncompressed sizes are unknown, UncompressedSize returns -1 and Percent returns 0, and must therefore not be used. This occurs for example with Zip archives created using ZipWriter, because a backwards seek before the compressed data of a file cannot be performed. Consequently, the values for compressed/uncompressed sizes cannot be modified. A Zip application such as WinZip, however, can seek back and write these values. As a result, when reading such an archive, UncompressedSize and Percent return useful values.

The InvalidPassword event

The ZipReader class additionally exposes an InvalidPassword event, which is raised when no password or an invalid password is provided to a password-protected archive. A ZipReaderInvalidPasswordEventArgs object provides the following properties for use in ZipReader's InvalidPassword event handler:

Property	Description
Abort	Indicates whether the Zip read operation should be aborted.
NewPassword	The new password to be used during the Zip read operation.
OldPassword	The password initially supplied.
ZipItemLocalHeader	The local header of the file currently being processed.

Examples

The following examples demonstrate how to use ZipWriter's ByteProgression event, as well as its event arguments.

using System.IO;
using Xceed.Zip.ReaderWriter;
//The target Zip archive.
using (FileStream fileStream1 = new FileStream(@"d:\testOutput\test.zip",
  FileMode.Create, FileAccess.Write))
{
  //Create a ZipWriter object around the stream.
  Xceed.Zip.ReaderWriter.ZipWriter zipWriter1 =
    new Xceed.Zip.ReaderWriter.ZipWriter(fileStream1);
  //Subscribe to the ByteProgression event
  zipWriter1.ByteProgression += new
    EventHandler<ZipWriterByteProgressionEventArgs>(zipWriter1_ByteProgression);
  DirectoryInfo directoryInfo = new DirectoryInfo(@"d:\test\");
  if (directoryInfo.Exists)
  {
    FileInfo[] files = directoryInfo.GetFiles("*.*",
      SearchOption.AllDirectories);
    foreach (FileInfo file in files)
    {
      //Create ZipItemLocalHeader for current item and write to archive.
      ZipItemLocalHeader zipItemLocalHeader1 = new ZipItemLocalHeader
        (file.Name);
      zipWriter1.WriteItemLocalHeader(zipItemLocalHeader1);
      byte[] buffer = new byte[1024];
      int read = 0;
      using (FileStream fs = file.OpenRead())
      {
        //Read the current item's data
        while ((read = fs.Read(buffer, 0, buffer.Length)) != 0)
        {
          //Write the current item's data to the Zip archive
          zipWriter1.WriteItemData(buffer, 0, read);
        }
      }
    }
    //Close the Zip archive
    zipWriter1.CloseZipFile();
    Console.WriteLine("Zip archive created.");
  }
}

//The ByteProgression event's handler. Demonstrates the use of
//the properties of ZipWriterByteProgressionEventArgs.
static void zipWriter1_ByteProgression(object sender, 
  ZipWriterByteProgressionEventArgs e)
{
  Console.WriteLine("Item {0}: CompressionMethod = {1},
    CompressionLevel = {2}.", e.ZipItemLocalHeader.FileName,
    e.ZipItemLocalHeader.CompressionMethod,
    e.ZipItemLocalHeader.CompressionLevel);
}

VB.NET

Imports System.IO
Imports Xceed.Zip.ReaderWriter
'The target Zip archive.
Using fileStream1 As New FileStream("d:\testOutput\test.zip",
  FileMode.Create, FileAccess.Write)

  'Create a ZipWriter object around the stream.
  Dim zipWriter1 As New Xceed.Zip.ReaderWriter.ZipWriter(fileStream1)
  'Subscribe to the ByteProgression event.
  AddHandler zipWriter1.ByteProgression, AddressOf Of
    ZipWriterByteProgressionEventArgs

  Dim directoryInfo As New DirectoryInfo("d:\test\")
  If directoryInfo.Exists Then
    Dim files As FileInfo() = directoryInfo.GetFiles("*.*",
      SearchOption.AllDirectories)
    For Each file As FileInfo In files
      'Create ZipItemLocalHeader for current item and write to archive.
      Dim zipItemLocalHeader1 As New ZipItemLocalHeader(file.Name)
      zipWriter1.WriteItemLocalHeader(zipItemLocalHeader1)
      Dim buffer As Byte() = New Byte(1023){}
      Dim read As Integer = 0
      Using fs As FileStream = file.OpenRead()
        'Read the current item's data
        read = fs.Read(buffer, 0, buffer.Length)
        Do While (read <> 0)
          'Write the current item's data to the Zip archive
          zipWriter1.WriteItemData(buffer, 0, read)
          read = fs.Read(buffer, 0, buffer.Length)
        Loop
      End Using
    Next file
    'Close the Zip archive
    zipWriter1.CloseZipFile()
    Console.WriteLine("Zip archive created.")
  End If
End Using

'The ByteProgression event's handler. Demonstrates the use of
'the properties of ZipWriterByteProgressionEventArgs.
Shared Sub zipWriter1_ByteProgression(ByVal sender As Object, ByVal e As ZipWriterByteProgressionEventArgs)
  Console.WriteLine("Item {0}: CompressionMethod = {1},
    CompressionLevel = {2}.", e.ZipItemLocalHeader.FileName,
    e.ZipItemLocalHeader.CompressionMethod,
    e.ZipItemLocalHeader.CompressionLevel)
End Sub

The following examples demonstrate how to use ZipReader's ByteProgression and InvalidPassword events, as well as their event arguments.

using System.IO;
using Xceed.Zip.ReaderWriter;
//The source Zip archive.
using (FileStream fileStream1 = new FileStream(@"d:\testOutput\test.zip",
  FileMode.Open, FileAccess.Read))
{
  //Must seek to the beginning of the stream before reading.
  fileStream1.Seek(0, SeekOrigin.Begin);
  //Create a ZipReader around the stream.
  Xceed.Zip.ReaderWriter.ZipReader zipReader1 =
    new Xceed.Zip.ReaderWriter.ZipReader(fileStream1);
  //Subscribe to the ByteProgression event
  zipReader1.ByteProgression +=
    new EventHandler<ZipReaderByteProgressionEventArgs>
    (zipReader1_ByteProgression);
  //Subscribe to the InvalidPassword event
  zipReader1.InvalidPassword +=
    new EventHandler<ZipReaderInvalidPasswordEventArgs>
    (zipReader1_InvalidPassword);
  ZipItemLocalHeader zipItemLocalHeader = null;
  //Read the local headers until no more are found
  while ((zipItemLocalHeader = zipReader1.ReadItemLocalHeader()) != null)
  {
    byte[] buffer = new byte[1024];
    int read = 0;
    //Read the item's data
    while ((read = zipReader1.ReadItemData(buffer, 0, buffer.Length)) > 0)
    {
      //Do something with the data in 'buffer'
    }
  }
}

//The InvalidPassword event's handler. Demonstrates the use of
//the properties of ZipReaderInvalidPasswordEventArgs.
static void zipReader1_InvalidPassword(object sender,
  ZipReaderInvalidPasswordEventArgs e)
{
  Console.Write("Enter password for file {0} (<Enter> alone to abort): ",
    e.ZipItemLocalHeader.FileName);
  string password = Console.ReadLine();
  if (string.IsNullOrEmpty(password))
  {
    //Set Abort to true to abort the read operation.
    e.Abort = true;
  }
  else
  {
    //Set NewPassword to the provided password. If it is the correct password,
    //the read operation will proceed. Otherwise, the InvalidPassword event is
    //raised again.
    e.NewPassword = password;
  }
}
//The ByteProgression event's handler. Demonstrates the use of
//the properties of ZipReaderByteProgressionEventArgs.
static void zipReader1_ByteProgression(object sender,
   ZipReaderByteProgressionEventArgs e)
{
  if (e.UncompressedSize == -1)
    Console.WriteLine("Processing item {0}: {1} bytes processed.",
      e.ZipItemLocalHeader.FileName, e.BytesProcessed);
  else
  {
    //UncompressedSize is not -1, so this property and the Percent property
    //return useful values.
    Console.WriteLine("Processing item {0}: {1} bytes processed ({3}%).
      (Uncompressed size = {3}.)",
      e.ZipItemLocalHeader.FileName,
      e.BytesProcessed,
      e.UncompressedSize,
      e.Percent);
  }
}

VB.NET

Imports System.IO
Imports Xceed.Zip.ReaderWriter
Using fileStream1 As New FileStream("d:\testOutput\test.zip",
  FileMode.Open, FileAccess.Read)

  'Must seek to the beginning of the stream before reading.
  fileStream1.Seek(0, SeekOrigin.Begin)
  'Create a ZipReader around the stream.
  Dim zipReader1 As New Xceed.Zip.ReaderWriter.ZipReader(fileStream1)
  'Subscribe to the ByteProgression event
  AddHandler zipReader1.ByteProgression, AddressOf Of
    ZipReaderByteProgressionEventArgs
  'Subscribe to the InvalidPassword event
  AddHandler zipReader1.InvalidPassword, AddressOf Of
    ZipReaderInvalidPasswordEventArgs
  Dim zipItemLocalHeader As ZipItemLocalHeader = Nothing
  'Read the local headers until no more are found
  Do While Not (zipItemLocalHeader = zipReader1.ReadItemLocalHeader()) Is
  Nothing
    Dim buffer As Byte() = New Byte(1023){}
    Dim read As Integer = 0
    'Read the item's data
    Do While (read = zipReader1.ReadItemData(buffer, 0, buffer.Length)) > 0
      'Do something with the data in 'buffer'
    Loop
  Loop
End Using

'The InvalidPassword event's handler. Demonstrates the use of
'the properties of ZipReaderInvalidPasswordEventArgs.
Shared Sub zipReader1_InvalidPassword(ByVal sender As Object, ByVal e As
  ZipReaderInvalidPasswordEventArgs)
  Console.Write("Enter password for file {0} (<Enter> alone to abort): ",
    e.ZipItemLocalHeader.FileName)
  Dim password As String = Console.ReadLine()
  'Set Abort to true to abort the read operation.
  If String.IsNullOrEmpty(password) Then
    e.Abort = True
  Else
    'Set NewPassword to the provided password. If it is the correct password,
    'the read operation will proceed. Otherwise, the InvalidPassword event is
    'raised again.
    e.NewPassword = password
  End If
End Sub

'The ByteProgression event's handler. Demonstrates the use of
'the properties of ZipReaderByteProgressionEventArgs.
Shared Sub zipReader1_ByteProgression(ByVal sender As Object, ByVal e As
  ZipReaderByteProgressionEventArgs)
  If e.UncompressedSize = -1 Then
    Console.WriteLine("Processing item {0}: {1} bytes processed.",
      e.ZipItemLocalHeader.FileName, e.BytesProcessed)
  Else
    'UncompressedSize is not -1, so this property and the Percent
    'property return useful values.
    Console.WriteLine("Processing item {0}: {1} bytes processed
      ({3}%). (Uncompressed size = {3}.)",
      e.ZipItemLocalHeader.FileName,
      e.BytesProcessed, e.UncompressedSize, e.Percent)
  End If
End Sub