PDF/A-3b allows the storage of attachments in PDF documents. With TX Text Control X19, you will be able to import and export those attachments from and to PDF documents. Typically, this is used to store machine-readable data as an attachment to the human-readable PDF version.

Document Revisions

But there many other applications for this powerful feature. Consider a PDF document that contains the most current version of a document as a PDF representation that can be read by any standard PDF viewer such as Adobe Acrobat Reader or browser readers such as PDF.js.

In addition to this "printable" version of the document, document revisions are stored in an editable format as attachments.

Creating documents with TX Text Control

The following code shows a sample implementation of such a VersionedDocument class:

public class VersionedDocument {
// member fields
private TextControl _textControl;
private string _filename;
// properties
public List<EmbeddedFile> Attachments { get; set; } = new List<EmbeddedFile>();
// constructor
// attach a TextControl and set filename
public VersionedDocument(TextControl textControl, string filename) {
_textControl = textControl;
_filename = filename;
}
// saves the current version as the visible representation
// and attaches the current version to the attachments
public void SaveDocument() {
// save current document from connected TextControl
byte[] baCurrentDocument;
_textControl.Save(out baCurrentDocument, BinaryStreamType.InternalUnicodeFormat);
// create a unique filename
var uniqueFilename = Guid.NewGuid().ToString() + ".tx";
// add the latest attachment
Attachments.Add(new EmbeddedFile(uniqueFilename, baCurrentDocument, null));
// use a temporary ServerTextControl to save the document
using (ServerTextControl tx = new TXTextControl.ServerTextControl()) {
tx.Create();
tx.Load(baCurrentDocument, BinaryStreamType.InternalUnicodeFormat);
// set the embedded files using the SaveSettings
SaveSettings saveSettings = new SaveSettings() {
EmbeddedFiles = Attachments.ToArray()
};
// save the file
tx.Save(_filename, StreamType.AdobePDF, saveSettings);
}
}
public void LoadDocument(string filename) {
// temporary ServerTextControl to handle attachments
using (ServerTextControl tx = new ServerTextControl()) {
tx.Create();
LoadSettings ls = new LoadSettings() {
PDFImportSettings = PDFImportSettings.LoadEmbeddedFiles
};
// load the PDF document
try {
tx.Load(filename, StreamType.AdobePDF, ls);
}
catch { throw; }
// store attachments
Attachments = ls.EmbeddedFiles?.ToList();
// get latest attachment
var latestAttachment = Attachments.OrderByDescending(c => c.CreationDate).First();
// load attachment into connected TextControl
try {
_textControl.Load(
(byte[])latestAttachment.Data,
BinaryStreamType.InternalUnicodeFormat);
}
catch { throw; }
// set the current filename
_filename = filename;
}
}
}
view raw VersionedDocument.cs hosted with ❤ by GitHub

In a sample Windows Forms application, in the constructor, VersionedDocument is connected to a TextControl ╰ TX Text Control .NET for Windows Forms
╰ TXTextControl Namespace
╰ TextControl Class
The TextControl class implements a Windows Forms control with high-level text editing features. class.

VersionedDocument _document;
public Form1() {
InitializeComponent();
_document = new VersionedDocument(textControl1, "test.pdf");
}
view raw test.cs hosted with ❤ by GitHub

The sample form consists of two Text Control instances, a button to save a revision, a button to load an existing document and a drop-down box that lists all embedded revisions:

Sample implementation

Saving the Document

In a first step, a first version of the document is created and saved as a revision in the document test.pdf by clicking the button Save Revision:

Sample implementation

The code behind the first button click is shown in the following code gist:

private void button1_Click(object sender, EventArgs e) {
_document.SaveDocument();
UpdateBinding();
}
view raw save.cs hosted with ❤ by GitHub

In a second step, the document in the left side Text Control is modified and saved as a new revision by clicking Save Revision:

Sample implementation

The drop-down box shows now two embedded revisions and by changing the selected index, the selected revision can be loaded separately into the second Text Control on the right side:

private void cbAttachments_SelectedIndexChanged(object sender, EventArgs e) {
if (cbAttachments.SelectedIndex != -1)
_document.Attachments[cbAttachments.SelectedIndex].Load(textControl2);
}
view raw load.cs hosted with ❤ by GitHub

Loading the Visual Representation

When loading an existing document, the newest version is loaded into the connected Text Control:

private void button2_Click(object sender, EventArgs e) {
_document.LoadDocument("test.pdf");
UpdateBinding();
}
view raw load.cs hosted with ❤ by GitHub

If this created document repository is opened in Adobe Acrobat Reader, the most current version is displayed as the PDF representation and the embedded revisions are shown in the list of attachments:

Adobe PDF

This is just another innovative idea from Text Control to integrate electronic document processing into business workflows. Stay tuned for more features of TX Text Control X19!