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Creating a ZIP file from a .Net WinForms App using DART PowerTCP Zip Compression

Introduction

This solution illustrates how we can create an application which selects one or more input files and generate a standard ZIP file which can be read by ZIP applications such as WinZip. The resultant file is ideal for transmission over the Internet. The application provides control over encryption, the compression level and provides progress information to the user.

Detail

The application will enable a user to select a list of files to be Zipped up, select a level of compression and whether or not encryption is required, and then specify the name/location of the output ZIP archive. The UI controls are all standard .Net controls and the work is done by Dart's PowerTCP Zip Compression component.

Setup

Get the sample code by downloading and installing the evaluation version of the product using the link above. Following installation, the sample .Net project will be located in:

My Documents\Dart Sample Applications\PowerTCP\Zip Compression for .NET Trial\VS2005\WinForms\Zipper

Select VB or C# directory according to your language preference.

The ZIP component of type Dart.PowerTCP.Zip.Archive is called archive1 and it sits on the form as a non-visual component.

Selecting files to be Zipped

The "Browse" button displays a common dialog control and this returns a string array of filenames which are loaded into archive1 in the FillList method:

C#
  private void FillList()
    {
      Working = true;
      //Add files to archive from specified search pattern
      statusZip.Text = "Searching for files ...";
      try
      {
        archive1.PreservePath = chkPreservePaths.Checked;
        foreach(string FileName in FilesSelected)
        {
          archive1.Add(FileName);
        }
      }
      catch (Exception ex)
      {
        if (!Killing) 
          MessageBox.Show(ex.Message);
      }
  .
  .

VB.Net
  Private Sub FillList()
    Working = True
    'Add files to archive from specified search pattern
    statusZip.Text = "Searching for files ..."

    Try
      archive1.PreservePath = chkPreservePaths.Checked

      For Each FileName As String In FilesSelected
        archive1.Add(FileName)
      Next FileName

    Catch ex As Exception
      If (Not Killing) Then
        MessageBox.Show(ex.Message)
      End If
    End Try
  .
  .

Note that the PreservePath property is set prior to loading the filenames into archive1 to ensure that the path information for each file is preserved or not according to the user's preference.

The list of files in the archive can be cleared using the Clear() method, which in this case is called from the Click handler of the "Clear" button.

Creating the archive

The code to create the archive is contained in the "Zip" button's click event handler.

A dialog is displayed which enables the user to specify the name and location of the output archive:

C#
  private void cmdZip_Click(object sender, System.EventArgs e)
  {
    Working = true;
    cmdZip.Capture = false;
    //Zip files in archive
    if (cmdZip.Text == "Zip!")
    {

      //Specify archive name
      dlgSave.Title = "Save Archive";
      dlgSave.Filter = "ZIP Files (*.zip)|*.zip";
      dlgSave.DefaultExt = ".zip";
      dlgSave.FileName = "";
      dlgSave.OverwritePrompt = true;
      if (dlgSave.ShowDialog() == DialogResult.OK)
      {
      .
      .

VB.Net
  Private Sub cmdZip_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdZip.Click
    Working = True
    cmdZip.Capture = False
    'Zip files in archive
    If cmdZip.Text = "Zip!" Then

      'Specify archive name
      dlgSave.Title = "Save Archive"
      dlgSave.Filter = "ZIP Files (*.zip)|*.zip"
      dlgSave.DefaultExt = ".zip"
      dlgSave.FileName = ""
      dlgSave.OverwritePrompt = True
      If dlgSave.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
      .
      .

If the user has checked the "Encrypt Files" check box then we display a form to get the password and encryption type. These are passed into the Zip component via the Password and DefaultEncryption properties respectively.

C#
      .
      .
      if (cbEncrypt.Checked)
      {
        frmPassword Pass = new frmPassword("");
        if (Pass.ShowDialog() == DialogResult.OK)
        {
          archive1.Password = Pass.txtPassword.Text;
          archive1.DefaultEncryption = (Encryption)Pass.cboEncryption.SelectedIndex + 1;
          for (int i = 0; i < archive1.Count; i++)
          {
            lvwFiles.Items[i].ForeColor = Color.Red;
          }
        }
      }
     .
     .

VB.Net
     .
     .
     If cbEncrypt.Checked Then
        Dim Pass As New frmPassword("")
        If Pass.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
          archive1.Password = Pass.txtPassword.Text
          archive1.DefaultEncryption = CType(Pass.cboEncryption.SelectedIndex, Encryption) + 1
          For i As Integer = 0 To archive1.Count - 1
            lvwFiles.Items(i).ForeColor = Color.Red
          Next i
        End If
      End If
     .
     .

Finally the Zipmethod is invoked, passing the filename of the Zip archive to be created...

C#
      archive1.Zip(dlgSave.FileName);

VB.Net
      archive1.Zip(dlgSave.FileName)

There are several events that Archive class can raise while executing the Zip method. We handle Progress, BusyChanged and Exception.

Progress is where we update the display of the progress bar.

The handler receives an instance of Dart.PowerTCP.Zip.ProgressEventArgs "e", which contains ProcessedTotalBytes and TotalBytes (as well as other useful values) and can be used to drive the progress bar as follows:

C#
  private void archive1_Progress(object sender, Dart.PowerTCP.Zip.ProgressEventArgs e)
  {
    try
    {
      progZip.Maximum = 100;
      double Percent = ((double)e.ProcessedTotalBytes / (double)e.TotalBytes) * 100;
      progZip.Value = Convert.ToInt16(Percent);
    }
    catch
    { }
  }

VB.Net
  Private Sub archive1_Progress(ByVal sender As Object, ByVal e As Dart.PowerTCP.Zip.ProgressEventArgs) Handles archive1.Progress
    Try
      progZip.Maximum = 100
      Dim Percent As Double = (CDbl(e.ProcessedTotalBytes) / CDbl(e.TotalBytes)) * 100
      progZip.Value = Convert.ToInt16(Percent)
    Catch
    End Try
  End Sub

Conclusion

Our solution shows that with just a couple of method calls we can generate a standard Zip archive containing one or several files. With just a little extra code PowerTCP Zip Compression can also encrypt the archive for added protection. This solution can easily be adapted to create a ZIip dialog for you application.

Of course, this is just a simple example and PowerTCP Zip Compression will also allow you to create more complex applications incluing compression and decompression via streams, advanced encryption and disk spanning.