PDF: Working with embedded files of PDF document

In This Topic

PDF document may include embedded files. For example, a PDF portfolio includes other PDF documents as embedded files.
PdfEmbeddedFile class represents a file, which is stored in PDF document, and allows to:

add a new embedded file into PDF document
obtain information about embedded file using PdfEmbeddedFile.CreationDate, PdfEmbeddedFile.ModifyDate, PdfEmbeddedFile.UncompressedLength properties
get and change the compression algorithm of embedded file using PdfEmbeddedFile.Compression property
save the embedded file to a file or stream using PdfEmbeddedFile.Save method

All embedded files of PDF document can be gathered using PdfDocument.EmbeddedFiles property.

Here is an example that demonstrates how to obtain information about all embedded files of PDF document:

VB.NET

' The project, which uses this code, must have references to the following assemblies:
' - Vintasoft.Imaging.Pdf

''' <summary>
''' Prints information about all embedded files of PDF document.
''' </summary>
''' <param name="pdfFilename">The filename of PDF document.</param>
Public Shared Sub PrintEmbeddedFilesInfo(pdfFilename As String)
    ' open PDF document
    Using document As New Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename, True)
        ' get the dictionary of embedded file specifications
        Dim embeddedFiles As Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecificationDictionary = document.EmbeddedFiles
        ' if dictionary is empty
        If embeddedFiles Is Nothing OrElse embeddedFiles.Count = 0 Then
            System.Console.WriteLine("No embedded files.")
        Else
            ' if dictionary is NOT empty
            System.Console.WriteLine(String.Format("There are {0} embedded files.", embeddedFiles.Count))
            ' counter of embedded files
            Dim counter As Integer = 1
            ' for each name-specification pair
            For Each embeddedFileInfo As System.Collections.Generic.KeyValuePair(Of String, Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecification) In embeddedFiles
                ' write name of the file specification
                System.Console.WriteLine(String.Format("{0}) Name: ""{1}""", System.Math.Max(System.Threading.Interlocked.Increment(counter),counter - 1), embeddedFileInfo.Key))
                ' get the file specification
                Dim embeddedFileSpecification As Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecification = embeddedFileInfo.Value
                ' write description of the file specification
                System.Console.WriteLine(String.Format("   Description: ""{0}""", embeddedFileSpecification.Description))
                ' write file name
                System.Console.WriteLine(String.Format("   Filename: ""{0}""", embeddedFileSpecification.Filename))
                ' write file system
                System.Console.WriteLine(String.Format("   FileSystem: ""{0}""", embeddedFileSpecification.FileSystem))
                ' get the embedded file
                Dim embeddedFile As Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFile = embeddedFileSpecification.EmbeddedFile
                System.Console.WriteLine(String.Format("   EmbeddedFile:"))
                ' write compression of the embedded file
                System.Console.WriteLine(String.Format("      Compression: {0}", embeddedFile.Compression))
                ' write creation date of the embedded file
                System.Console.WriteLine(String.Format("      CreationDate: {0}", embeddedFile.CreationDate))
                ' write modification date of the embedded file
                System.Console.WriteLine(String.Format("      ModifyDate: {0}", embeddedFile.ModifyDate))
                ' write uncompressed length of the embedded file
                System.Console.WriteLine(String.Format("      UncompressedLength: {0} bytes", embeddedFile.UncompressedLength))
                ' write compressed length of the embedded file
                System.Console.WriteLine(String.Format("      CompressedLength: {0} bytes", embeddedFile.Length))
                System.Console.WriteLine()
            Next
        End If
    End Using
End Sub

// The project, which uses this code, must have references to the following assemblies:
// - Vintasoft.Imaging.Pdf

/// <summary>
/// Prints information about all embedded files of PDF document.
/// </summary>
/// <param name="pdfFilename">The filename of PDF document.</param>
public static void PrintEmbeddedFilesInfo(string pdfFilename)
{
    // open PDF document
    using (Vintasoft.Imaging.Pdf.PdfDocument document = 
        new Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename, true))
    {
        // get the dictionary of embedded file specifications
        Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecificationDictionary embeddedFiles = document.EmbeddedFiles;
        // if dictionary is empty
        if (embeddedFiles == null || embeddedFiles.Count == 0)
        {
            System.Console.WriteLine("No embedded files.");
        }
        // if dictionary is NOT empty
        else
        {
            System.Console.WriteLine(string.Format("There are {0} embedded files.", embeddedFiles.Count));
            // counter of embedded files
            int counter = 1;
            // for each name-specification pair
            foreach (System.Collections.Generic.KeyValuePair<string, Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecification> 
                embeddedFileInfo in embeddedFiles)
            {
                // write name of the file specification
                System.Console.WriteLine(string.Format("{0}) Name: \"{1}\"", counter++, embeddedFileInfo.Key));
                // get the file specification
                Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecification embeddedFileSpecification = embeddedFileInfo.Value;
                // write description of the file specification
                System.Console.WriteLine(string.Format("   Description: \"{0}\"", embeddedFileSpecification.Description));
                // write file name
                System.Console.WriteLine(string.Format("   Filename: \"{0}\"", embeddedFileSpecification.Filename));
                // write file system
                System.Console.WriteLine(string.Format("   FileSystem: \"{0}\"", embeddedFileSpecification.FileSystem));
                // get the embedded file
                Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFile embeddedFile = embeddedFileSpecification.EmbeddedFile;
                System.Console.WriteLine(string.Format("   EmbeddedFile:"));
                // write compression of the embedded file
                System.Console.WriteLine(string.Format("      Compression: {0}", embeddedFile.Compression));
                // write creation date of the embedded file
                System.Console.WriteLine(string.Format("      CreationDate: {0}", embeddedFile.CreationDate));
                // write modification date of the embedded file
                System.Console.WriteLine(string.Format("      ModifyDate: {0}", embeddedFile.ModifyDate));
                // write uncompressed length of the embedded file
                System.Console.WriteLine(string.Format("      UncompressedLength: {0} bytes", embeddedFile.UncompressedLength));
                // write compressed length of the embedded file
                System.Console.WriteLine(string.Format("      CompressedLength: {0} bytes", embeddedFile.Length));
                System.Console.WriteLine();
            }
        }
    }
}

PdfEmbeddedFileSpecificationDictionary class represents a dictionary of embedded files, which are stored in PDF document, and allows to add or remove embedded files.

Here is an example that demonstrates how to embed file into PDF document:

VB.NET

' The project, which uses this code, must have references to the following assemblies:
' - Vintasoft.Imaging.Pdf

''' <summary>
''' Embeds specified file into specified PDF document.
''' </summary>
''' <param name="pdfFilename">The filename of PDF document.</param>
''' <param name="embeddingFilename">The filename of embedding file.</param>
Public Shared Sub EmbedFileIntoPdfDocument(pdfFilename As String, embeddingFilename As String)
    ' open PDF document
    Using document As New Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename)
        ' if embedded files are absent
        If document.EmbeddedFiles Is Nothing Then
            ' create new dictionary
            document.EmbeddedFiles = New Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecificationDictionary(document)
        End If

        ' create embedded file instance
        Dim embeddedFile As New Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFile(document, embeddingFilename, Vintasoft.Imaging.Pdf.PdfCompression.Zip)
        ' create embedded file specification
        Dim fileSpecification As New Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecification(embeddingFilename, embeddedFile)
        ' set description of the embedded file specification
        fileSpecification.Description = "Test embedding"
        ' add the embedded file specification to the dictionary
        document.EmbeddedFiles.Add(embeddingFilename, fileSpecification)
        ' save changes to the source
        document.SaveChanges()
    End Using
End Sub

// The project, which uses this code, must have references to the following assemblies:
// - Vintasoft.Imaging.Pdf

/// <summary>
/// Embeds specified file into specified PDF document.
/// </summary>
/// <param name="pdfFilename">The filename of PDF document.</param>
/// <param name="embeddingFilename">The filename of embedding file.</param>
public static void EmbedFileIntoPdfDocument(string pdfFilename, string embeddingFilename)
{
    // open PDF document
    using (Vintasoft.Imaging.Pdf.PdfDocument document = 
        new Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename))
    {
        // if embedded files are absent
        if (document.EmbeddedFiles == null)
            // create new dictionary
            document.EmbeddedFiles = 
                new Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecificationDictionary(document);

        // create embedded file instance
        Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFile embeddedFile = 
            new Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFile(
                document, embeddingFilename, Vintasoft.Imaging.Pdf.PdfCompression.Zip);
        // create embedded file specification
        Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecification fileSpecification = 
            new Vintasoft.Imaging.Pdf.Tree.PdfEmbeddedFileSpecification(embeddingFilename, embeddedFile);
        // set description of the embedded file specification
        fileSpecification.Description = "Test embedding";
        // add the embedded file specification to the dictionary
        document.EmbeddedFiles.Add(embeddingFilename, fileSpecification);
        // save changes to the source
        document.SaveChanges();
    }
}

Here is an example that demonstrates how to remove embedded file from PDF document:

VB.NET

' The project, which uses this code, must have references to the following assemblies:
' - Vintasoft.Imaging.Pdf

''' <summary>
''' Removes the embedded file from PDF document by the name of embedded file specification.
''' </summary>
''' <param name="pdfFilename">The filename of PDF document.</param>
''' <param name="embeddedFileName">Name of the embedded file specification.</param>
''' <returns><b>true</b> if the file is found and successfully removed; otherwise, <b>false</b>.</returns>
Public Shared Function RemoveEmbeddedFileFromPdfDocument(pdfFilename As String, embeddedFileName As String) As Boolean
    ' open PDF document
    Using document As New Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename)
        ' if embedded files are absent
        If document.EmbeddedFiles Is Nothing OrElse document.EmbeddedFiles.Count = 0 Then
            Return False
        End If
        ' try to remove embedded file specification
        If Not document.EmbeddedFiles.Remove(embeddedFileName) Then
            Return False
        End If
        ' save changes to the source
        document.SaveChanges()
        Return True
    End Using
End Function

// The project, which uses this code, must have references to the following assemblies:
// - Vintasoft.Imaging.Pdf

/// <summary>
/// Removes the embedded file from PDF document by the name of embedded file specification.
/// </summary>
/// <param name="pdfFilename">The filename of PDF document.</param>
/// <param name="embeddedFileName">Name of the embedded file specification.</param>
/// <returns><b>true</b> if the file is found and successfully removed; otherwise, <b>false</b>.</returns>
public static bool RemoveEmbeddedFileFromPdfDocument(string pdfFilename, string embeddedFileName)
{
    // open PDF document
    using (Vintasoft.Imaging.Pdf.PdfDocument document = new Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename))
    {
        // if embedded files are absent
        if (document.EmbeddedFiles == null || document.EmbeddedFiles.Count == 0)
            return false;
        // try to remove embedded file specification
        if (!document.EmbeddedFiles.Remove(embeddedFileName))
            return false;
        // save changes to the source
        document.SaveChanges();
        return true;
    }
}

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