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As a part of a project I'm working on, a new requirement has arisen for me to be able to generate multiple PDF files and then merge them together before they are delivered to our client(s). For this, I've started working on a reusable solution that implements the iTextSharp library using code I've taken from the Java example listed on page 187 of the sample chapter from "iText in Action". I've attempted to make it able to handle a number of possible scenarios through overloaded methods, and everything seems to be working correctly, as far as I can tell.

What I'm most concerned about at this point is doing my best to put in appropriate error handling. Since this is my first time working with this library, I'm not sure yet about any of the "gotcha" exceptions that I might be overlooking.

''' <summary>
''' Class for manipulating PDF files
''' </summary>
Public Class PDFManipulator
#Region "PUBLIC PROPERTIES"
 Public Property Warnings As List(Of String)
 Public Property Errors As List(Of String)
#End Region
 ''' <summary>
 ''' The file property to use for sorting the files before merging
 ''' </summary>
 Public Enum PDFMergeSortOrder
 Original
 FileDate
 FileName
 FileNameWithDirectory
 End Enum
#Region "PUBLIC METHODS"
#Region "OVERLOAD METHODS"
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, OutputFileName, False, PDFMergeSortOrder.Original, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, OutputFileName, False, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, OutputFileName, False, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, OutputFileName, False, SortOrder, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, OutputFileName, OverwriteExistingPDF, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Dim PDFFiles As New List(Of System.IO.FileInfo)
 Dim PDFFolder As New System.IO.DirectoryInfo(PDFFilePath)
 For Each PDF As System.IO.FileInfo In PDFFolder.GetFiles("*.pdf")
 If PDF.Length > 0 Then
 PDFFiles.Add(PDF)
 Else
 If Warnings Is Nothing Then
 Warnings = New List(Of String)
 End If
 Warnings.Add("Empty file : " & PDF.FullName & " not merged into output file.")
 End If
 Next PDF
 If RecurseSubFolders Then
 PDFFiles.AddRange(GetFilesFromSubFoldersForMerge(PDFFolder))
 End If
 Return Merge(PDFFiles, OutputFileName, OverwriteExistingPDF, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, OutputFileName, False, PDFMergeSortOrder.Original, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, OutputFileName, False, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, OutputFileName, False, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, OutputFileName, False, SortOrder, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, OutputFileName, OverwriteExistingPDF, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Dim PDFFiles As New List(Of System.IO.FileInfo)
 For Each PDF As System.IO.FileInfo In PDFFileDirectory.GetFiles("*.pdf").OrderBy(Function(f As System.IO.FileInfo) f.LastWriteTime)
 If PDF.Length > 0 Then
 PDFFiles.Add(PDF)
 Else
 If Warnings Is Nothing Then
 Warnings = New List(Of String)
 End If
 Warnings.Add("Empty file : " & PDF.FullName & " not merged into output file.")
 End If
 Next PDF
 If RecurseSubFolders Then
 PDFFiles.AddRange(GetFilesFromSubFoldersForMerge(PDFFileDirectory))
 End If
 Return Merge(PDFFiles, OutputFileName, OverwriteExistingPDF, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileNames">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFileNames As List(Of String), ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return Merge(PDFFileNames, OutputFileName, False, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileNames">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFileNames As List(Of String), ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean) As System.IO.FileInfo
 Return Merge(PDFFileNames, OutputFileName, False, PDFMergeSortOrder.Original)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileNames">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFileNames As List(Of String), ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Dim PDFFiles As New List(Of System.IO.FileInfo)
 For Each PDFName As String In PDFFileNames
 If System.IO.File.Exists(PDFName) Then
 Dim PDF As New System.IO.FileInfo(PDFName)
 If PDF.Length > 0 Then
 PDFFiles.Add(PDF)
 Else
 If Warnings Is Nothing Then
 Warnings = New List(Of String)
 End If
 Warnings.Add("Empty file : " & PDF.FullName & " not merged into output file.")
 End If
 End If
 Next PDFName
 Return Merge(PDFFiles, OutputFileName, OverwriteExistingPDF, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFiles">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFiles As List(Of System.IO.FileInfo), ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean) As System.IO.FileInfo
 Return Merge(PDFFiles, OutputFileName, False, PDFMergeSortOrder.Original)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFiles">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFiles As List(Of System.IO.FileInfo), ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return Merge(PDFFiles, OutputFileName, False, SortOrder)
 End Function
#End Region
#Region "MASTER MERGE METHOD"
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFiles">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFiles As List(Of System.IO.FileInfo), ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Dim ResultFile As System.IO.FileInfo = Nothing
 Dim ContinueMerge As Boolean = True
 If OverwriteExistingPDF Then
 If System.IO.File.Exists(OutputFileName) Then
 Try
 System.IO.File.Delete(OutputFileName)
 Catch ex As Exception
 ContinueMerge = False
 If Errors Is Nothing Then
 Errors = New List(Of String)
 End If
 Errors.Add("Could not delete existing output file.")
 Throw
 End Try
 End If
 End If
 If ContinueMerge Then
 Dim OutputPDF As iTextSharp.text.Document = Nothing
 Dim Copier As iTextSharp.text.pdf.PdfCopy = Nothing
 Dim PDFStream As System.IO.FileStream = Nothing
 Dim SortedList As New List(Of System.IO.FileInfo)
 Try
 Select Case SortOrder
 Case PDFMergeSortOrder.Original
 SortedList = PDFFiles
 Case PDFMergeSortOrder.FileDate
 SortedList = PDFFiles.OrderBy(Function(f As System.IO.FileInfo) f.LastWriteTime).ToList
 Case PDFMergeSortOrder.FileName
 SortedList = PDFFiles.OrderBy(Function(f As System.IO.FileInfo) f.Name).ToList
 Case PDFMergeSortOrder.FileNameWithDirectory
 SortedList = PDFFiles.OrderBy(Function(f As System.IO.FileInfo) f.FullName).ToList
 End Select
 If Not IO.Directory.Exists(New IO.FileInfo(OutputFileName).DirectoryName) Then
 Try
 IO.Directory.CreateDirectory(New IO.FileInfo(OutputFileName).DirectoryName)
 Catch ex As Exception
 ContinueMerge = False
 If Errors Is Nothing Then
 Errors = New List(Of String)
 End If
 Errors.Add("Could not create output directory.")
 Throw
 End Try
 End If
 If ContinueMerge Then
 OutputPDF = New iTextSharp.text.Document
 PDFStream = New System.IO.FileStream(OutputFileName, System.IO.FileMode.OpenOrCreate)
 Copier = New iTextSharp.text.pdf.PdfCopy(OutputPDF, PDFStream)
 OutputPDF.Open()
 For Each PDF As System.IO.FileInfo In SortedList
 If ContinueMerge Then
 Dim InputReader As iTextSharp.text.pdf.PdfReader = Nothing
 Try
 InputReader = New iTextSharp.text.pdf.PdfReader(PDF.FullName)
 For page As Integer = 1 To InputReader.NumberOfPages
 Copier.AddPage(Copier.GetImportedPage(InputReader, page))
 Next page
 If InputReader.IsRebuilt Then
 If Warnings Is Nothing Then
 Warnings = New List(Of String)
 End If
 Warnings.Add("Damaged PDF: " & PDF.FullName & " repaired and successfully merged into output file.")
 End If
 Catch InvalidEx As iTextSharp.text.exceptions.InvalidPdfException
 'Skip this file
 If Errors Is Nothing Then
 Errors = New List(Of String)
 End If
 Errors.Add("Invalid PDF: " & PDF.FullName & " not merged into output file.")
 Catch FormatEx As iTextSharp.text.pdf.BadPdfFormatException
 'Skip this file
 If Errors Is Nothing Then
 Errors = New List(Of String)
 End If
 Errors.Add("Bad PDF Format: " & PDF.FullName & " not merged into output file.")
 Catch PassworddEx As iTextSharp.text.exceptions.BadPasswordException
 'Skip this file
 If Errors Is Nothing Then
 Errors = New List(Of String)
 End If
 Errors.Add("Password-protected PDF: " & PDF.FullName & " not merged into output file.")
 Catch OtherEx As Exception
 ContinueMerge = False
 Finally
 If Not InputReader Is Nothing Then
 InputReader.Close()
 InputReader.Dispose()
 End If
 End Try
 End If
 Next PDF
 End If
 Catch ex As iTextSharp.text.pdf.PdfException
 ResultFile = Nothing
 ContinueMerge = False
 If Errors Is Nothing Then
 Errors = New List(Of String)
 End If
 Errors.Add("iTextSharp Error: " & ex.Message)
 If System.IO.File.Exists(OutputFileName) Then
 If Not OutputPDF Is Nothing Then
 OutputPDF.Close()
 OutputPDF.Dispose()
 End If
 If Not PDFStream Is Nothing Then
 PDFStream.Close()
 PDFStream.Dispose()
 End If
 If Not Copier Is Nothing Then
 Copier.Close()
 Copier.Dispose()
 End If
 System.IO.File.Delete(OutputFileName)
 End If
 Throw
 Catch other As Exception
 ResultFile = Nothing
 ContinueMerge = False
 If Errors Is Nothing Then
 Errors = New List(Of String)
 End If
 Errors.Add("General Error: " & other.Message)
 If System.IO.File.Exists(OutputFileName) Then
 If Not OutputPDF Is Nothing Then
 OutputPDF.Close()
 OutputPDF.Dispose()
 End If
 If Not PDFStream Is Nothing Then
 PDFStream.Close()
 PDFStream.Dispose()
 End If
 If Not Copier Is Nothing Then
 Copier.Close()
 Copier.Dispose()
 End If
 System.IO.File.Delete(OutputFileName)
 End If
 Throw
 Finally
 If Not OutputPDF Is Nothing Then
 OutputPDF.Close()
 OutputPDF.Dispose()
 End If
 If Not PDFStream Is Nothing Then
 PDFStream.Close()
 PDFStream.Dispose()
 End If
 If Not Copier Is Nothing Then
 Copier.Close()
 Copier.Dispose()
 End If
 If System.IO.File.Exists(OutputFileName) Then
 If ContinueMerge Then
 ResultFile = New System.IO.FileInfo(OutputFileName)
 If ResultFile.Length <= 0 Then
 ResultFile = Nothing
 Try
 System.IO.File.Delete(OutputFileName)
 Catch ex As Exception
 Throw
 End Try
 End If
 Else
 ResultFile = Nothing
 Try
 System.IO.File.Delete(OutputFileName)
 Catch ex As Exception
 Throw
 End Try
 End If
 Else
 ResultFile = Nothing
 End If
 End Try
 End If
 Return ResultFile
 End Function
#End Region
#End Region
#Region "PRIVATE METHODS"
 ''' <summary>
 ''' Recursive method to find all PDF files in subfolders of a given directory and
 ''' add them to the original list for merging
 ''' </summary>
 ''' <param name="RootFolder">The DirectoryInfo object in which to look for sub-directories containing additional PDF files to merge</param>
 ''' <returns>A list of all the PDF files found in all subfolders of the root</returns>
 Private Function GetFilesFromSubFoldersForMerge(ByVal RootFolder As System.IO.DirectoryInfo) As List(Of System.IO.FileInfo)
 Dim PDFFiles As New List(Of System.IO.FileInfo)
 For Each PDFSubFolder As System.IO.DirectoryInfo In RootFolder.GetDirectories
 For Each PDF As System.IO.FileInfo In PDFSubFolder.GetFiles("*.pdf")
 If PDF.Length > 0 Then
 PDFFiles.Add(PDF)
 Else
 If Warnings Is Nothing Then
 Warnings = New List(Of String)
 End If
 Warnings.Add("Empty file : " & PDF.FullName & " not merged into output file.")
 End If
 Next PDF
 PDFFiles.AddRange(GetFilesFromSubFoldersForMerge(PDFSubFolder))
 Next PDFSubFolder
 Return PDFFiles
 End Function
#End Region
End Class

I'm hoping to add some methods for splitting PDF's, adding watermarks, etc. at some point in the future, but for now, I'm just trying to get the current functionality shored up the best I can. Of course, any comments or suggestions about anything in the code are absolutely welcome, regardless of whether or not it has specifically to do with error handling.

EDIT: I've added a couple of extra Catch conditions to the "master" Merge method (in the inner Try) that I believe may be useful, although I haven't been able to specifically test for those conditions yet. I added the following:

  • iTextSharp.text.pdf.BadPdfFormatException
  • iTextSharp.text.exceptions.BadPasswordException

I also added some Dispose calls in some of the other exception handling in the outer Try...Catch block before attempting to delete the output PDF file to make sure it isn't in use.

Additionally, I added a small block of code to add a Warning if the original PDF is repaired before being added to the output file.

Zeta
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asked Feb 4, 2018 at 5:47
\$\endgroup\$
3
  • \$\begingroup\$ Suggestion for a new tag(s): iText with a tag synonym of iTextSharp \$\endgroup\$ Commented Feb 4, 2018 at 21:56
  • 1
    \$\begingroup\$ I've rolled the changes back. Please do not update the code in your question to incorporate feedback from answers, doing so goes against the Question + Answer style of Code Review. This is not a forum where you should keep the most updated version in your question. Please see what you may and may not do after receiving answers . \$\endgroup\$ Commented Feb 7, 2018 at 16:22
  • \$\begingroup\$ Thank you, and I apologize as I hadn't read that Meta post. My intent was simply to share the "cleaned up" version of the code. \$\endgroup\$ Commented Feb 7, 2018 at 16:43

2 Answers 2

2
\$\begingroup\$

Only focusing on the "monster" method Merge().

The usage of ContinueMerge seems senseless because this is set only to False in a Catch block where later the exception is thrown up the call stack. The only exception from this pattern is for catching the OtherEx which by the way is named poorly. For the case that ContinueMerge is False the loop where you caught the exception just isn't doing anything anymore hence you could Exit For or just return from the method.

But the biggest improvement would be if you could get rid of the repeated code targeting your List<T>'s 

If Errors Is Nothing Then
 Errors = New List(Of String)
End If

By newing them in the constructor you could omit a lot of code. You have this pattern 11 times in your code which makes 33 lines of code.

What sense does it have to first apply a SortOrder and afterwards check if you can create the output directory? A lot of computing time may be lost if you can't create the directory.

Catching an exception which you just Throw doesn't add anything useful. E.g here 

Try
 System.IO.File.Delete(OutputFileName)
Catch ex As Exception
 Throw
End Try

you could just remove the Try..Catch which would have the same result.

By using a Using statement for the objects 

Dim OutputPDF As iTextSharp.text.Document = Nothing
Dim Copier As iTextSharp.text.pdf.PdfCopy = Nothing
Dim PDFStream As System.IO.FileStream = Nothing

you could save a lot of code as well. Right now you Close() and Dispose() these objects at 3 places which wouldn't be necessary at all by using a Using statement. A Using statement basically is just a Try..Finally where the disposable object will be disposed in the Finally part. In addition, a call to Dispose() will, in good coded objects, always close any ressources hence a call to Close() won't be needed.

answered Feb 5, 2018 at 7:42
\$\endgroup\$
1
  • \$\begingroup\$ Excellent suggestions. Thank you so much for your help. As I said in my other question, I'm entirely self-taught, so, even though I've been programming for several years, I've probably gotten into some habits and patterns (e.g., not using the Using statement, etc.). I'll look into revising the method(s) with your suggestions. \$\endgroup\$ Commented Feb 5, 2018 at 7:50
1
\$\begingroup\$

I've modified the "master" method to incorporate the suggestions provided by @Heslacher. I had been concerned about the fact that the overloaded methods didn't have their own Try...Catch blocks around the calls to the "master" method, but after testing with and without them, I now understand that, as long as the original calling method has it, any exceptions will "bubble-up " through the overloads as expected/intended.

Additionally, by testing the exception handling, I found a couple of places in my original code where I was incorrectly passing a "default" value into the "master" method instead of using the value provided by the overload. I've corrected these occurrences, and everything should be "cleaned up". In the spirit of sharing, here is the updated code:

''' <summary>
''' Class for manipulating PDF files
''' </summary>
Public Class PDFManipulator
#Region "PUBLIC PROPERTIES"
 Public Property Warnings As List(Of String)
 Public Property Errors As List(Of String)
#End Region
#Region "PDF MERGE METHODS"
 ''' <summary>
 ''' The file property to use for sorting the files before merging
 ''' </summary>
 Public Enum PDFMergeSortOrder
 Original
 FileDate
 FileName
 FileNameWithDirectory
 End Enum
#Region "PUBLIC METHODS"
#Region "CONSTRUCTOR"
 Public Sub New()
 Errors = New List(Of String)
 Warnings = New List(Of String)
 End Sub
#End Region
#Region "OVERLOAD METHODS"
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, False, OutputFileName, False, PDFMergeSortOrder.Original, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, UseSmartMerge, OutputFileName, False, PDFMergeSortOrder.Original, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, False, OutputFileName, False, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, UseSmartMerge, OutputFileName, False, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, False, OutputFileName, False, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, UseSmartMerge, OutputFileName, False, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, False, OutputFileName, False, SortOrder, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <c>Nothing</c> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, UseSmartMerge, OutputFileName, False, SortOrder, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, False, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, UseSmartMerge, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFilePath, False, OutputFileName, OverwriteExistingPDF, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFilePath">The path in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified path for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFilePath As String, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Dim PDFFiles As New List(Of System.IO.FileInfo)
 Dim PDFFolder As New System.IO.DirectoryInfo(PDFFilePath)
 For Each PDF As System.IO.FileInfo In PDFFolder.GetFiles("*.pdf")
 If PDF.Length > 0 Then
 PDFFiles.Add(PDF)
 Else
 Warnings.Add("Empty file : " & PDF.FullName & " not merged into output file.")
 End If
 Next PDF
 If RecurseSubFolders Then
 PDFFiles.AddRange(GetFilesFromSubFoldersForMerge(PDFFolder))
 End If
 Return Merge(PDFFiles, UseSmartMerge, OutputFileName, OverwriteExistingPDF, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, False, OutputFileName, False, PDFMergeSortOrder.Original, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, UseSmartMerge, OutputFileName, False, PDFMergeSortOrder.Original, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, False, OutputFileName, False, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, UseSmartMerge, OutputFileName, False, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, False, OutputFileName, False, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, UseSmartMerge, OutputFileName, False, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, False, OutputFileName, False, SortOrder, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, UseSmartMerge, OutputFileName, False, SortOrder, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, False, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, UseSmartMerge, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original, RecurseSubFolders)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, False, OutputFileName, OverwriteExistingPDF, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return MergeAll(PDFFileDirectory, UseSmartMerge, OutputFileName, OverwriteExistingPDF, SortOrder, False)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileDirectory">The Directory in which to search for PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <param name="RecurseSubFolders">Identifies whether or not to look in subfolders of the specified Directory for additional PDF files</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function MergeAll(ByVal PDFFileDirectory As System.IO.DirectoryInfo, ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder, ByVal RecurseSubFolders As Boolean) As System.IO.FileInfo
 Dim PDFFiles As New List(Of System.IO.FileInfo)
 For Each PDF As System.IO.FileInfo In PDFFileDirectory.GetFiles("*.pdf").OrderBy(Function(f As System.IO.FileInfo) f.LastWriteTime)
 If PDF.Length > 0 Then
 PDFFiles.Add(PDF)
 Else
 Warnings.Add("Empty file : " & PDF.FullName & " not merged into output file.")
 End If
 Next PDF
 If RecurseSubFolders Then
 PDFFiles.AddRange(GetFilesFromSubFoldersForMerge(PDFFileDirectory))
 End If
 Return Merge(PDFFiles, UseSmartMerge, OutputFileName, OverwriteExistingPDF, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileNames">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFileNames As List(Of String), ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return Merge(PDFFileNames, False, OutputFileName, False, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileNames">A list of specific PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function Merge(ByVal PDFFileNames As List(Of String), ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return Merge(PDFFileNames, UseSmartMerge, OutputFileName, False, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileNames">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFileNames As List(Of String), ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean) As System.IO.FileInfo
 Return Merge(PDFFileNames, False, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileNames">A list of specific PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function Merge(ByVal PDFFileNames As List(Of String), ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean) As System.IO.FileInfo
 Return Merge(PDFFileNames, UseSmartMerge, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFileNames">A list of specific PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function Merge(ByVal PDFFileNames As List(Of String), ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Dim PDFFiles As New List(Of System.IO.FileInfo)
 For Each PDFName As String In PDFFileNames
 If System.IO.File.Exists(PDFName) Then
 Dim PDF As New System.IO.FileInfo(PDFName)
 If PDF.Length > 0 Then
 PDFFiles.Add(PDF)
 Else
 Warnings.Add("Empty file : " & PDF.FullName & " not merged into output file.")
 End If
 End If
 Next PDFName
 Return Merge(PDFFiles, UseSmartMerge, OutputFileName, OverwriteExistingPDF, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFiles">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFiles As List(Of System.IO.FileInfo), ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean) As System.IO.FileInfo
 Return Merge(PDFFiles, False, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFiles">A list of specific PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function Merge(ByVal PDFFiles As List(Of System.IO.FileInfo), ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean) As System.IO.FileInfo
 Return Merge(PDFFiles, UseSmartMerge, OutputFileName, OverwriteExistingPDF, PDFMergeSortOrder.Original)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFiles">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 Public Overloads Function Merge(ByVal PDFFiles As List(Of System.IO.FileInfo), ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return Merge(PDFFiles, False, OutputFileName, False, SortOrder)
 End Function
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFiles">A list of specific PDF files to merge</param>
 ''' <param name="UseSmartMerge">Identifies whether to use a regular <see cref="iTextSharp.text.pdf.PdfCopy"/> or the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> for merging</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function Merge(ByVal PDFFiles As List(Of System.IO.FileInfo), ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Return Merge(PDFFiles, UseSmartMerge, OutputFileName, False, SortOrder)
 End Function
#End Region
#Region "MASTER MERGE METHOD"
 ''' <summary>
 ''' Merges multiple PDF files into a single PDF file
 ''' </summary>
 ''' <param name="PDFFiles">A list of specific PDF files to merge</param>
 ''' <param name="OutputFileName">The PDF file to create from the merged PDF files</param>
 ''' <param name="OverwriteExistingPDF">If the specified PDF file already exists, identifies whether or not to overwrite the existing file</param>
 ''' <param name="SortOrder">Identifies the order in which to add the source PDF files to the output file</param>
 ''' <returns>A FileInfo object representing the merged PDF if successful. <cref>Nothing</cref> if unsuccessful.</returns>
 ''' <remarks>Using the <see cref="iTextSharp.text.pdf.PdfCopy"/> (<paramref name="UseSmartMerge"/> = <c>False</c>) may result in larger files, 
 ''' while using the <see cref="iTextSharp.text.pdf.PdfSmartCopy"/> (<paramref name="UseSmartMerge"/> = <c>True</c>) may result in longer processing times.</remarks>
 Public Overloads Function Merge(ByVal PDFFiles As List(Of System.IO.FileInfo), ByVal UseSmartMerge As Boolean, ByVal OutputFileName As String, ByVal OverwriteExistingPDF As Boolean, ByVal SortOrder As PDFMergeSortOrder) As System.IO.FileInfo
 Dim ResultFile As System.IO.FileInfo = Nothing
 Dim SortedList As New List(Of System.IO.FileInfo)
 Dim PDFCopier As iTextSharp.text.pdf.PdfCopy = Nothing
 Dim SmartPDFCopier As iTextSharp.text.pdf.PdfSmartCopy = Nothing
 If OverwriteExistingPDF Then
 If System.IO.File.Exists(OutputFileName) Then
 Try
 System.IO.File.Delete(OutputFileName)
 Catch ex As Exception
 Errors.Add("Could not delete existing output file.")
 Throw
 End Try
 End If
 ElseIf System.IO.File.Exists(OutputFileName) Then
 Errors.Add("Output file already exists.")
 Return Nothing
 End If
 If Not IO.Directory.Exists(New IO.FileInfo(OutputFileName).DirectoryName) Then
 Try
 IO.Directory.CreateDirectory(New IO.FileInfo(OutputFileName).DirectoryName)
 Catch ex As Exception
 Errors.Add("Could not create output directory.")
 Throw
 End Try
 End If
 Select Case SortOrder
 Case PDFMergeSortOrder.Original
 SortedList = PDFFiles
 Case PDFMergeSortOrder.FileDate
 SortedList = PDFFiles.OrderBy(Function(f As System.IO.FileInfo) f.LastWriteTime).ToList
 Case PDFMergeSortOrder.FileName
 SortedList = PDFFiles.OrderBy(Function(f As System.IO.FileInfo) f.Name).ToList
 Case PDFMergeSortOrder.FileNameWithDirectory
 SortedList = PDFFiles.OrderBy(Function(f As System.IO.FileInfo) f.FullName).ToList
 End Select
 Try
 Using OutputPDF As New iTextSharp.text.Document
 Using PDFStream As New System.IO.FileStream(OutputFileName, System.IO.FileMode.OpenOrCreate)
 If UseSmartMerge Then
 SmartPDFCopier = New iTextSharp.text.pdf.PdfSmartCopy(OutputPDF, PDFStream)
 Else
 PDFCopier = New iTextSharp.text.pdf.PdfCopy(OutputPDF, PDFStream)
 End If
 OutputPDF.Open()
 For Each PDF As System.IO.FileInfo In SortedList
 Try
 Using InputReader As New iTextSharp.text.pdf.PdfReader(PDF.FullName)
 For Page As Integer = 1 To InputReader.NumberOfPages
 If UseSmartMerge Then
 SmartPDFCopier.AddPage(SmartPDFCopier.GetImportedPage(InputReader, Page))
 Else
 PDFCopier.AddPage(PDFCopier.GetImportedPage(InputReader, Page))
 End If
 Next Page
 If InputReader.IsRebuilt Then
 Warnings.Add("Damaged PDF: " & PDF.FullName & " repaired and successfully merged into output file.")
 End If
 End Using
 Catch InvalidEx As iTextSharp.text.exceptions.InvalidPdfException
 'Skip this file
 Errors.Add("Invalid PDF: " & PDF.FullName & " not merged into output file.")
 Catch FormatEx As iTextSharp.text.pdf.BadPdfFormatException
 'Skip this file
 Errors.Add("Bad PDF Format: " & PDF.FullName & " not merged into output file.")
 Catch PassworddEx As iTextSharp.text.exceptions.BadPasswordException
 'Skip this file
 Errors.Add("Password-protected PDF: " & PDF.FullName & " not merged into output file.")
 Catch OtherEx As Exception
 ResultFile = Nothing
 Errors.Add("Other Error: " & OtherEx.Message & vbCrLf & vbCrLf & PDF.FullName & " not merged into output file.")
 If System.IO.File.Exists(OutputFileName) Then
 System.IO.File.Delete(OutputFileName)
 End If
 Exit For
 End Try
 Next PDF
 End Using
 End Using
 Catch ex As iTextSharp.text.pdf.PdfException
 ResultFile = Nothing
 Errors.Add("iTextSharp Error: " & ex.Message)
 If Not PDFCopier Is Nothing Then
 PDFCopier.Dispose()
 End If
 If Not SmartPDFCopier Is Nothing Then
 SmartPDFCopier.Dispose()
 End If
 If System.IO.File.Exists(OutputFileName) Then
 System.IO.File.Delete(OutputFileName)
 End If
 Throw
 Catch other As Exception
 ResultFile = Nothing
 Errors.Add("Other Error: " & other.Message)
 If Not PDFCopier Is Nothing Then
 PDFCopier.Dispose()
 End If
 If Not SmartPDFCopier Is Nothing Then
 SmartPDFCopier.Dispose()
 End If
 If System.IO.File.Exists(OutputFileName) Then
 System.IO.File.Delete(OutputFileName)
 End If
 Throw
 Finally
 If Not PDFCopier Is Nothing Then
 PDFCopier.Dispose()
 End If
 If Not SmartPDFCopier Is Nothing Then
 SmartPDFCopier.Dispose()
 End If
 If System.IO.File.Exists(OutputFileName) Then
 ResultFile = New System.IO.FileInfo(OutputFileName)
 If ResultFile.Length <= 0 Then
 ResultFile = Nothing
 System.IO.File.Delete(OutputFileName)
 End If
 Else
 ResultFile = Nothing
 End If
 End Try
 Return ResultFile
 End Function
#End Region
#End Region
#Region "PRIVATE METHODS"
 ''' <summary>
 ''' Recursive method to find all PDF files in subfolders of a given directory and
 ''' add them to the original list for merging
 ''' </summary>
 ''' <param name="RootFolder">The DirectoryInfo object in which to look for sub-directories containing additional PDF files to merge</param>
 ''' <returns>A list of all the PDF files found in all subfolders of the root</returns>
 Private Function GetFilesFromSubFoldersForMerge(ByVal RootFolder As System.IO.DirectoryInfo) As List(Of System.IO.FileInfo)
 Dim PDFFiles As New List(Of System.IO.FileInfo)
 For Each PDFSubFolder As System.IO.DirectoryInfo In RootFolder.GetDirectories
 For Each PDF As System.IO.FileInfo In PDFSubFolder.GetFiles("*.pdf")
 If PDF.Length > 0 Then
 PDFFiles.Add(PDF)
 Else
 Warnings.Add("Empty file : " & PDF.FullName & " not merged into output file.")
 End If
 Next PDF
 PDFFiles.AddRange(GetFilesFromSubFoldersForMerge(PDFSubFolder))
 Next PDFSubFolder
 Return PDFFiles
 End Function
#End Region
#End Region
End Class

EDIT: I found one other little "gotcha" in the "master" method. If the OverwriteExistingPDF parameter is set to False and the file specified by the OutputFileName already exists, I needed to exit the method. I'm not sure if it would be better to generate a new exception object and try to throw that back to the calling method, but, for now I've simply set it to return Nothing. Updated the code in this CW answer to reflect the change.

\$\endgroup\$
1
  • \$\begingroup\$ Thank you for converting it to a CW post. I wasn't sure if I should or not, so I appreciate the moderator intervention. :) \$\endgroup\$ Commented Feb 7, 2018 at 20:52

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