Progress Event

'Declaration
 
Public Event Progress As EventHandler(Of DocumentProgressEventArgs)

' Windows API functions needed to load/delete an EMF
   <DllImport("gdi32.dll")> _
   Private Shared Function GetEnhMetaFile(ByVal lpszMetaFile As String) As IntPtr
   End Function
   <DllImport("gdi32.dll")> _
   Private Shared Function DeleteEnhMetaFile(ByVal hemf As IntPtr) As Boolean
   End Function

   Private Sub DocumentWriterProgressExample()
      ' Create a new instance of the LEADTOOLS Document Writer
      Dim docWriter As New DocumentWriter()

      ' Get the file names to use
      Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "DocumentWriter.pdf")

      Dim emfFileNames() As String = _
      { _
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.emf"), _
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr2.emf"), _
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr3.emf"), _
         Path.Combine(LEAD_VARS.ImagesDir, "Ocr4.emf") _
      }

      ' Show the progress dialog
      Using dlg As New MyProgressDialog(docWriter, emfFileNames, pdfFileName)
         If (dlg.ShowDialog() = DialogResult.OK) Then
            MessageBox.Show("Done!")
         Else
            MessageBox.Show("User has canceled the operation or an error occured.")
         End If
      End Using
   End Sub

   ' Dialog box to show the 
   Private Class MyProgressDialog
      Inherits Form
      ' The controls on the dialog
      Private _descriptionLabel As Label
      Private _progressBar As ProgressBar
      Private _cancelButton As Button
      Private _operation As String

      ' Conversion properties
      Private _docWriter As DocumentWriter
      Private _emfFileNames() As String
      Private _pdfFileName As String

      ' Has the operation been canceled?
      Private _isCanceled As Boolean
      ' Is the dialog working?
      Private _isWorking As Boolean

      Public Sub New(ByVal docWriter As DocumentWriter, ByVal emfFileNames() As String, ByVal pdfFileName As String)
         InitializeComponent()

         _docWriter = docWriter
         _emfFileNames = emfFileNames
         _pdfFileName = pdfFileName

         _isCanceled = False
         _isWorking = True
      End Sub

      Protected Overrides Sub OnLoad(ByVal e As EventArgs)
         ' To keep the UI functioning, do the conversion in a separate thread
         BeginInvoke(New MethodInvoker(AddressOf DoWork))

         MyBase.OnLoad(e)
      End Sub

      Private Sub DoWork()
         ' Subscribe to the progress event
         AddHandler _docWriter.Progress, AddressOf _docWriter_Progress

         ' Create the document
         _operation = "Creating the document..."
         _docWriter.BeginDocument(_pdfFileName, DocumentFormat.Pdf)

         ' Add the pages
         For i As Integer = 0 To _emfFileNames.Length - 1
            ' Use the Windows API to load the EMF
            Dim emfHandle As IntPtr = GetEnhMetaFile(_emfFileNames(i))

            ' Add the page, notice we will not be using image/text feature (the default)
            Dim page As DocumentPage = DocumentPage.Empty
            page.EmfHandle = emfHandle
            page.Image = Nothing

            _operation = String.Format("Adding page {0} of {1}...", i + 1, _emfFileNames.Length)
            _docWriter.AddPage(page)

            ' Use the Windows API to delete the EMF
            DeleteEnhMetaFile(emfHandle)
         Next

         ' Finally finish writing the PDF file on disk
         _operation = "Finishing the document..."
         _docWriter.EndDocument()

         RemoveHandler _docWriter.Progress, AddressOf _docWriter_Progress

         ' Set the dialog results based on whether the user has canceled the operation
         If (_isCanceled) Then
            DialogResult = DialogResult.Cancel
         Else
            DialogResult = DialogResult.OK
         End If

         ' The dialog can be closed now
         _isWorking = False

         ' We are done
         Close()
      End Sub

      Private Sub _docWriter_Progress(ByVal sender As Object, ByVal e As DocumentProgressEventArgs)
         ' Update the description label progress bar
         _descriptionLabel.Text = _operation
         _progressBar.Value = e.Percentage

         ' Check if the user clicked the Cancel button, if so, abort the operation
         If (_isCanceled) Then
            e.Cancel = True
         End If

         Application.DoEvents()
      End Sub

      Private Sub _cancelButton_Click(ByVal sender As Object, ByVal e As EventArgs)
         ' Set the isCanceled variable to true, this will break from the
         ' progress callback and closes the dialog

         _isCanceled = True
      End Sub

      Protected Overrides Sub OnFormClosing(ByVal e As FormClosingEventArgs)
         ' Dont allow the form to close while the callback is still working
         ' Instead, cancel the operation
         If (_isWorking) Then
            e.Cancel = True
         End If

         MyBase.OnFormClosing(e)
      End Sub

      Private Sub InitializeComponent()
         ' Create the controls in this form, a text label, a progress bar and a cancel button
         SuspendLayout()

         ' Text label
         _descriptionLabel = New Label()
         _descriptionLabel.Location = New Point(26, 21)
         _descriptionLabel.Name = "_descriptionLabel"
         _descriptionLabel.Size = New Size(367, 23)
         _descriptionLabel.TabIndex = 0
         _descriptionLabel.TextAlign = ContentAlignment.MiddleLeft
         _descriptionLabel.Text = "Creating final document..."

         ' Progress bar
         _progressBar = New ProgressBar()
         _progressBar.Location = New Point(27, 47)
         _progressBar.Name = "_progressBar"
         _progressBar.Size = New Size(364, 23)
         _progressBar.TabIndex = 1

         ' Cancel button
         _cancelButton = New Button()
         _cancelButton.DialogResult = DialogResult.Cancel
         _cancelButton.Location = New Point(172, 76)
         _cancelButton.Name = "_cancelButton"
         _cancelButton.Size = New Size(75, 23)
         _cancelButton.TabIndex = 2
         _cancelButton.Text = "Cancel"
         _cancelButton.UseVisualStyleBackColor = True
         AddHandler _cancelButton.Click, AddressOf _cancelButton_Click

         ' Add the controls
         Controls.Add(_descriptionLabel)
         Controls.Add(_progressBar)
         Controls.Add(_cancelButton)

         ' Initialize the dialog
         AutoScaleDimensions = New SizeF(6.0F, 13.0F)
         AutoScaleMode = AutoScaleMode.Font
         CancelButton = _cancelButton
         ClientSize = New Size(420, 118)
         FormBorderStyle = FormBorderStyle.FixedDialog
         MaximizeBox = False
         MinimizeBox = False
         Name = "MyProgressDialog"
         ShowInTaskbar = False
         StartPosition = FormStartPosition.CenterParent
         Text = "DocumentWriter Progress Example"

         ResumeLayout()
      End Sub
   End Class

Public NotInheritable Class LEAD_VARS
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class