I need to retrieve the layer2 text from a signature. How can I get the description (under the signature image) using itextsharp? below is the code I'm using to get the sign date and username:
PdfReader reader = new PdfReader(pdfPath, System.Text.Encoding.UTF8.GetBytes(MASTER_PDF_PASSWORD));
using (MemoryStream memoryStream = new MemoryStream())
{
PdfStamper stamper = new PdfStamper(reader, memoryStream);
AcroFields acroFields = stamper.AcroFields;
List<String> names = acroFields.GetSignatureNames();
foreach (String name in names)
{
PdfPKCS7 pk = acroFields.VerifySignature(name);
String userName = PdfPKCS7.GetSubjectFields(pk.SigningCertificate).GetField("CN");
Console.WriteLine("Sign Date: " + pk.SignDate.ToString() + " Name: " + userName);
// Here i need to retrieve the description underneath the signature image
}
reader.RemoveUnusedObjects();
reader.Close();
stamper.Writer.CloseStream = false;
if (stamper != null)
{
stamper.Close();
}
}
and below is the code I used to set the description
PdfStamper st = PdfStamper.CreateSignature(reader, memoryStream, '\0', null, true);
PdfSignatureAppearance sap = st.SignatureAppearance;
sap.Render = PdfSignatureAppearance.SignatureRender.GraphicAndDescription;
sap.Layer2Font = font;
sap.Layer2Text = "Some text that i want to retrieve";
Thank you.
While Bruno addressed the issue starting with a PDF containing a "layer 2", allow me to first state that using these "signature layers" in PDF signature appearances is not required by the PDF specification, the specification actually does not even know these layers at all! Thus, if you try to parse a specific layer, you may not find such a "layer" or, even worse, find something that looks like that layer (a XObject named n2) which contains the wrong data.
That been said, though, Whether you look for text from a layer 2 or from the signature appearance as a whole, you can use iTextSharp text extraction capabilities. I used Bruno's code as base for retrieving the n2 layer.
public static void ExtractSignatureTextFromFile(FileInfo file)
{
try
{
Console.Out.Write("File: {0}\n", file);
using (var pdfReader = new PdfReader(file.FullName))
{
AcroFields fields = pdfReader.AcroFields;
foreach (string name in fields.GetSignatureNames())
{
Console.Out.Write(" Signature: {0}\n", name);
iTextSharp.text.pdf.AcroFields.Item item = fields.GetFieldItem(name);
PdfDictionary widget = item.GetWidget(0);
PdfDictionary ap = widget.GetAsDict(PdfName.AP);
if (ap == null)
continue;
PdfStream normal = ap.GetAsStream(PdfName.N);
if (normal == null)
continue;
Console.Out.Write(" Content of normal appearance: {0}\n", extractText(normal));
PdfDictionary resources = normal.GetAsDict(PdfName.RESOURCES);
if (resources == null)
continue;
PdfDictionary xobject = resources.GetAsDict(PdfName.XOBJECT);
if (xobject == null)
continue;
PdfStream frm = xobject.GetAsStream(PdfName.FRM);
if (frm == null)
continue;
PdfDictionary res = frm.GetAsDict(PdfName.RESOURCES);
if (res == null)
continue;
PdfDictionary xobj = res.GetAsDict(PdfName.XOBJECT);
if (xobj == null)
continue;
PRStream n2 = (PRStream) xobj.GetAsStream(PdfName.N2);
if (n2 == null)
continue;
Console.Out.Write(" Content of normal appearance, layer 2: {0}\n", extractText(n2));
}
}
}
catch (Exception ex)
{
Console.Error.Write("Error... " + ex.StackTrace);
}
}
public static String extractText(PdfStream xObject)
{
PdfDictionary resources = xObject.GetAsDict(PdfName.RESOURCES);
ITextExtractionStrategy strategy = new LocationTextExtractionStrategy();
PdfContentStreamProcessor processor = new PdfContentStreamProcessor(strategy);
processor.ProcessContent(ContentByteUtils.GetContentBytesFromContentObject(xObject), resources);
return strategy.GetResultantText();
}
For the sample file signature_n2.pdf Bruno used you get this:
File: ...\signature_n2.pdf
Signature: Signature1
Content of normal appearance: This document was signed by Bruno
Specimen.
Content of normal appearance, layer 2: This document was signed by Bruno
Specimen.
As this sample uses the layer 2 as the OP expects, it already contains the text in question.
Please take a look at the following PDF: signature_n2.pdf. It contains a signature with the following text in the n2 layer:
This document was signed by Bruno
Specimen.
Before we can write code to extract this text, we should use iText RUPS to look at the internal structure of the PDF, so that we can find out where this /n2 layer is stored:
Based on this information, we can start writing our code. See the GetN2fromSig example:
public static void main(String[] args) throws IOException {
PdfReader reader = new PdfReader(SRC);
AcroFields fields = reader.getAcroFields();
Item item = fields.getFieldItem("Signature1");
PdfDictionary widget = item.getWidget(0);
PdfDictionary ap = widget.getAsDict(PdfName.AP);
PdfStream normal = ap.getAsStream(PdfName.N);
PdfDictionary resources = normal.getAsDict(PdfName.RESOURCES);
PdfDictionary xobject = resources.getAsDict(PdfName.XOBJECT);
PdfStream frm = xobject.getAsStream(PdfName.FRM);
PdfDictionary res = frm.getAsDict(PdfName.RESOURCES);
PdfDictionary xobj = res.getAsDict(PdfName.XOBJECT);
PRStream n2 = (PRStream) xobj.getAsStream(PdfName.N2);
byte[] stream = PdfReader.getStreamBytes(n2);
System.out.println(new String(stream));
}
We get the widget annotation for the signature field with name "signature1". Based on the info from RUPS, we know that we have to get the resources (/Resources) of the normal (/N) appearance (/AP). In the /XObjects dictionary, we'll find a form XObject named /FRM. This XObject has in turn also some /Resources, more specifically two /XObjects, one named /n0, the other one named /n2.
We get the stream of the /n2 object and we convert it to an uncompressed byte[]. When we print this array as a String, we get the following result:
BT
1 0 0 1 0 49.55 Tm
/F1 12 Tf
(This document was signed by Bruno)Tj
1 0 0 1 0 31.55 Tm
(Specimen.)Tj
ET
This is PDF syntax. BT and ET stand for "Begin Text" and "End Text". The Tm operator set the text matrix. The Tf operator set the font. Tj shows the strings that are delimited by ( and ). If you want the plain text, it's sufficient to extract only the text that is between parentheses.
Related
I am trying to overlay two PDF files using iText7/C#.
The first one is kind of background and the second one is containing form fields.
Everything works fine and only problem is that I lose fonts from the second file.
I try as follows:
static public bool Overlay(string back_path, string front_path, string merge_path)
{
PdfReader reader;
PdfDocument pdf = null, front;
try
{
reader = new PdfReader(back_path);
pdf = new PdfDocument(reader, new PdfWriter(merge_path));
front = new PdfDocument(new PdfReader(front_path));
var form = PdfAcroForm.GetAcroForm(front, false);
PdfAcroForm dform = PdfAcroForm.GetAcroForm(pdf, true);
IDictionary<String, PdfFormField> fields = form.GetFormFields();
// copy styles
dform.SetDefaultResources(form.GetDefaultResources());
dform.SetDefaultAppearance(form.GetDefaultAppearance().GetValue());
// do overlay
foreach (KeyValuePair<string, PdfFormField> pair in fields)
{
try
{
var field = pair.Value;
PdfPage page = field.GetWidgets().First().GetPage();
int pg_no = front.GetPageNumber(page);
if (pg_no < front_start_page || pg_no > front_end_page)
continue;
PdfObject copied = field.GetPdfObject().CopyTo(pdf, true);
PdfFormField copiedField = PdfFormField.MakeFormField(copied, pdf);
// The following returns null. If it returns something, I think I could use copiedField.setFont(font).
// var font = field.GetFont();
dform.AddField(copiedField, pdf.GetPage(pg_no));
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine($"Overlaying field {pair.Key} failed. ({ex.Message})");
}
}
pdf.Close();
return true;
}
catch (Exception ex)
{
throw new OverlayException(ex.Message);
}
}
public static PdfDictionary get_font_dict(PdfDocument pdfDoc)
{
PdfDictionary acroForm = pdfDoc.GetCatalog().GetPdfObject().GetAsDictionary(PdfName.AcroForm);
if (acroForm == null)
{
return null;
}
PdfDictionary dr = acroForm.GetAsDictionary(PdfName.DR);
if (dr == null)
{
return null;
}
PdfDictionary font = dr.GetAsDictionary(PdfName.Font);
return font;
}
So basically I get all fonts from the second PDF and copy them to the final PDF.
But it does not work.
Logically, I think setting font of the original field to the copied one is the right way.
I mean PdfFormField.GetFont() and SetFont().
But it always returns null.
In a comment you clarified:
the background PDF can be assumed not to have form fields or annotations. I mean we can assume background PDF only contains static content (scanned form) and the front PDF only contains formfields.
In that case the easiest way to implement your method is to add the background as xobject to the form PDF instead of adding the form to the background PDF.
You can simply do that like this:
PdfReader formReader = new PdfReader(front_path);
PdfReader backReader = new PdfReader(back_path);
PdfWriter writer = new PdfWriter(merge_path);
using (PdfDocument source = new PdfDocument(backReader))
using (PdfDocument target = new PdfDocument(formReader, writer))
{
PdfFormXObject xobject = source.GetPage(1).CopyAsFormXObject(target);
PdfPage targetFirstPage = target.GetFirstPage();
PdfStream stream = targetFirstPage.NewContentStreamBefore();
PdfCanvas pdfCanvas = new PdfCanvas(stream, targetFirstPage.GetResources(), target);
Rectangle cropBox = targetFirstPage.GetCropBox();
pdfCanvas.AddXObject(xobject, cropBox.GetX(), cropBox.GetY());
}
Depending on the exact static contents of the background and the form PDF, you might want to use NewContentStreamAfter instead of NewContentStreamBefore or even to use some nifty blend mode to get the exact static content look you want.
I extract the pictures found in a PDF document with itextsharp using this snippet (thanks #Scott Stanford from this topic) :
private static IList<System.Drawing.Image> GetImagesFromPdfDict(PdfDictionary dict, PdfReader doc)
{
List<Image> images = new List<Image>();
if (dict == null)
return images;
PdfDictionary res = (PdfDictionary)(PdfReader.GetPdfObject(dict.Get(PdfName.RESOURCES)));
if (res == null)
return images;
PdfDictionary xobj = (PdfDictionary)(PdfReader.GetPdfObject(res.Get(PdfName.XOBJECT)));
if (xobj == null)
return images;
foreach (PdfName name in xobj.Keys)
{
PdfObject obj = xobj.Get(name);
if (obj.IsIndirect())
{
PdfDictionary tg = (PdfDictionary)(PdfReader.GetPdfObject(obj));
PdfName subtype = (PdfName)(PdfReader.GetPdfObject(tg.Get(PdfName.SUBTYPE)));
if (PdfName.IMAGE.Equals(subtype))
{
int xrefIdx = ((PRIndirectReference)obj).Number;
PdfObject pdfObj = doc.GetPdfObject(xrefIdx);
PdfStream str = (PdfStream)(pdfObj);
iTextSharp.text.pdf.parser.PdfImageObject pdfImage =
new iTextSharp.text.pdf.parser.PdfImageObject((PRStream)str);
System.Drawing.Image img = pdfImage.GetDrawingImage();
images.Add(img);
}
else if (PdfName.FORM.Equals(subtype) || PdfName.GROUP.Equals(subtype))
{
images.AddRange(GetImagesFromPdfDict(tg, doc));
}
}
}
return images;
}
Then I save the extracted System.Drawing.Image into jpeg files like this :
image.Save(path, ImageFormat.Jpeg);
This works well for most pictures, but in some rare cases, the saved pictures look like this :
(I have added the black stroke after the generation of the image because these pictures concern real people).
The white color turns into pink, and the black colors turn into green shades.
I tried to save the System.Drawing.Image with several encodings (System.Drawing.Imaging.EncoderParameter, also with PNG...) but I did not managed to change its output. So I think this problem come from the extraction of the image from the PDF and the creation of the System.Drawing.Image.
To test if the pictures are not corrupted, I tried with the online PDF extractor http://www.extractpdf.com/. This tool managed to extract these pictures without any problem.
Does anybody have an idea to solve this issue ?
I'm trying to generate a pdf from image with iTextSharp, but I'm getting the following errors: iTextSharp.Image does not contain a definition for 'getInstance' and 'iTextSharp.text.Document does not contain a definition for 'add' and 'iTextSharp.text.Document does not contain a definition for 'newPage' and iTextSharp.text.Image does not contain a definition for 'scalePercent'**
I have already add the iText Library (itextsharp, itextsharp.pdfa and itextshar.xtra). here is my code:
private void button3_Click_1(object sender, EventArgs e)
{
saveFileDialog1.FileName = "name.pdf";
if (saveFileDialog1.ShowDialog() == DialogResult.OK)
{
using (Bitmap bitmap = new Bitmap(panel1.ClientSize.Width,
panel1.ClientSize.Height))
{
panel1.DrawToBitmap(bitmap, panel1.ClientRectangle);
bitmap.Save("C:\\" + (nPaginasPDF + 1) + ".bmp", ImageFormat.Bmp);
}
Document doc = new Document();
PdfWriter.GetInstance(doc, new FileOutputStream(yourOutFile));
doc.Open();
for (int iCnt = 0; iCnt < nPaginasPDF; iCnt++)
{
iTextSharp.text.Image image1 = iTextSharp.text.Image.GetInstance("C:\\" + (iCnt + 1) + ".bmp");
image1.ScalePercent(23f);
doc.NewPage();
doc.Add(image1);
}
using (var Stream = saveFileDialog1.OpenFile())
{
doc.Save(Stream);
}
doc.Close();
}
Both #Nenad and #MaxStoun are correct, you just need to adapt the Java conventions to .Net. Additionally, you'll also need to swap the Java FileOutputStream for the .Net System.IO.FileStream object.
EDIT
You have some "magic variables" in there that I need to work around. For instance, I'm not 100% sure what you're doing with your for loop so I just removed it for this sample. Also, I don't have write permissions to my c:\ directory to I'm saving to the desktop. Otherwise, this code should hopefully get you on the correct path.
//I don't know what you're doing with this variable so I'm just setting it to something
int nPaginasPDF = 10;
//I can't write to my C: drive so I'm saving to the desktop
string saveFolder = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
//Set the default file name
saveFileDialog1.FileName = "name.pdf";
//If the user presses "OK"
if (saveFileDialog1.ShowDialog() == DialogResult.OK) {
//Create a bitmap and save it to disk
using (Bitmap bitmap = new Bitmap(panel1.ClientSize.Width, panel1.ClientSize.Height)) {
panel1.DrawToBitmap(bitmap, panel1.ClientRectangle);
//Path.Combine is a safer way to build file pathes
bitmap.Save(System.IO.Path.Combine(saveFolder, nPaginasPDF + ".bmp"), ImageFormat.Bmp);
}
//Create a new file stream instance with some locks for safety
using (var fs = new System.IO.FileStream(saveFileDialog1.FileName, System.IO.FileMode.Create, System.IO.FileAccess.Write, System.IO.FileShare.None)) {
//Create our iTextSharp document
using (var doc = new Document()) {
//Bind a PdfWriter to the Document and FileStream
using (var writer = PdfWriter.GetInstance(doc, fs)) {
//Open the document for writing
doc.Open();
//Get an instance of our image
iTextSharp.text.Image image1 = iTextSharp.text.Image.GetInstance(System.IO.Path.Combine(saveFolder, nPaginasPDF + ".bmp"));
//Sacle it
image1.ScalePercent(23f);
//Add a new page
doc.NewPage();
//Add our image to the document
doc.Add(image1);
//Close our document for writing
doc.Close();
}
}
}
}
If you use iText documentation or books for Java, you need to adapt things a bit for .NET. In your example, since .NET implicit getters and setters for properties, this:
var instance = iTextSharp.Image.getInstance();
becomes this:
var instance = iTextSharp.Image.Instance;
Second issue: method names in Java are camel case, vs .NET pascal case, so this (camelCase):
image1.scalePercent(23f);
doc.newPage();
doc.add(image1);
becomes this (PascalCase):
image1.ScalePercent(23f);
doc.NewPage();
doc.Add(image1);
And so on. Just apply .NET code naming conventions instead of Java's.
You'll upper first letter in method name (I just downloaded it from Nuget)
Image.getInstance(); => Image.GetInstance();
doc.add(image1); => doc.Add(image1);
Following is the function I am writing to create PDF using iTextSharp.
Let me explain the function ...
I am here creating a PDF file from the another Template PDF file. The template PDF file is sent to this function in bytes[], then I create pdfReader from this...
From pdfReader I create pdfStamper (i.e. new PDF file) and write the response values to its fields. It is working fine... only issue is fint size of values is much large...
public void GeneratePrintPDFTest(ResponseGroup actual, Pages page, byte[] filebyte, out string pdfname, string localstorage)
{
string rootPath = #"D:/FOP-PDF/";
var pdfReader = new PdfReader(filebyte);
var pdfStamper = new PdfStamper(pdfReader,new FileStream(rootPath.ToString(CultureInfo.InvariantCulture) + page.PageId.ToString(CultureInfo.InvariantCulture)
+ ".pdf",FileMode.Create));
pdfname = rootPath.ToString(CultureInfo.InvariantCulture) + page.PageId.ToString(CultureInfo.InvariantCulture) + ".pdf";
AcroFields pdfFormFields = pdfStamper.AcroFields;
foreach (DictionaryEntry de in pdfReader.AcroFields.Fields)
{
var response = actual.Responses.Where(obj => obj.ITPPageFieldKeyId == Convert.ToInt32(de.Key.ToString())).Select(obj => obj).FirstOrDefault();
if (response != null)
{
if (response.ResponseValues != null && !string.IsNullOrEmpty(response.ResponseValues.ToString())
&& response.ResponseValues.ToString() != "0" && !string.IsNullOrEmpty(response.DataItemID)
&& response.DataItemID != "0")
{
if (response.PrintFormulaResult || response.PageFieldFormulaId == 0)
{
pdfFormFields.SetField(de.Key.ToString(), response.ResponseValues.ToString());
}
}
}
}
pdfStamper.FormFlattening = false;
pdfStamper.Close();
}
I tried following solutions but of no use....
float fSize = 10;
pdfFormFields.SetFieldProperty(de.Key.ToString(), de.Key.ToString(), fSize, null);
I also doubt it may be coming from the template PDF file, but if so how could I change it programatically.
Please help me with this... Thanks in advance...
I need to post several (read: a lot) PDF files to the web but many of them have hard coded file:// links and links to non-public locations. I need to read through these PDFs and update the links to the proper locations. I've started writing an app using itextsharp to read through the directories and files, find the PDFs and iterate through each page. What I need to do next is find the links and then update the incorrect ones.
string path = "c:\\html";
DirectoryInfo rootFolder = new DirectoryInfo(path);
foreach (DirectoryInfo di in rootFolder.GetDirectories())
{
// get pdf
foreach (FileInfo pdf in di.GetFiles("*.pdf"))
{
string contents = string.Empty;
Document doc = new Document();
PdfReader reader = new PdfReader(pdf.FullName);
using (MemoryStream ms = new MemoryStream())
{
PdfWriter writer = PdfWriter.GetInstance(doc, ms);
doc.Open();
for (int p = 1; p <= reader.NumberOfPages; p++)
{
byte[] bt = reader.GetPageContent(p);
}
}
}
}
Quite frankly, once I get the page content I'm rather lost on this when it comes to iTextSharp. I've read through the itextsharp examples on sourceforge, but really didn't find what I was looking for.
Any help would be greatly appreciated.
Thanks.
This one is a little complicated if you don't know the internals of the PDF format and iText/iTextSharp's abstraction/implementation of it. You need to understand how to use PdfDictionary objects and look things up by their PdfName key. Once you get that you can read through the official PDF spec and poke around a document pretty easily. If you do care I've included the relevant parts of the PDF spec in parenthesis where applicable.
Anyways, a link within a PDF is stored as an annotation (PDF Ref 12.5). Annotations are page-based so you need to first get each page's annotation array individually. There's a bunch of different possible types of annotations so you need to check each one's SUBTYPE and see if its set to LINK (12.5.6.5). Every link should have an ACTION dictionary associated with it (12.6.2) and you want to check the action's S key to see what type of action it is. There's a bunch of possible ones for this, link's specifically could be internal links or open file links or play sound links or something else (12.6.4.1). You are looking only for links that are of type URI (note the letter I and not the letter L). URI Actions (12.6.4.7) have a URI key that holds the actual address to navigate to. (There's also an IsMap property for image maps that I can't actually imagine anyone using.)
Whew. Still reading? Below is a full working VS 2010 C# WinForms app based on my post here targeting iTextSharp 5.1.1.0. This code does two main things: 1) Create a sample PDF with a link in it pointing to Google.com and 2) replaces that link with a link to bing.com. The code should be pretty well commented but feel free to ask any questions that you might have.
using System;
using System.Text;
using System.Windows.Forms;
using iTextSharp.text;
using iTextSharp.text.pdf;
using System.IO;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
//Folder that we are working in
private static readonly string WorkingFolder = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "Hyperlinked PDFs");
//Sample PDF
private static readonly string BaseFile = Path.Combine(WorkingFolder, "OldFile.pdf");
//Final file
private static readonly string OutputFile = Path.Combine(WorkingFolder, "NewFile.pdf");
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
CreateSamplePdf();
UpdatePdfLinks();
this.Close();
}
private static void CreateSamplePdf()
{
//Create our output directory if it does not exist
Directory.CreateDirectory(WorkingFolder);
//Create our sample PDF
using (iTextSharp.text.Document Doc = new iTextSharp.text.Document(PageSize.LETTER))
{
using (FileStream FS = new FileStream(BaseFile, FileMode.Create, FileAccess.Write, FileShare.Read))
{
using (PdfWriter writer = PdfWriter.GetInstance(Doc, FS))
{
Doc.Open();
//Turn our hyperlink blue
iTextSharp.text.Font BlueFont = FontFactory.GetFont("Arial", 12, iTextSharp.text.Font.NORMAL, iTextSharp.text.BaseColor.BLUE);
Doc.Add(new Paragraph(new Chunk("Go to URL", BlueFont).SetAction(new PdfAction("http://www.google.com/", false))));
Doc.Close();
}
}
}
}
private static void UpdatePdfLinks()
{
//Setup some variables to be used later
PdfReader R = default(PdfReader);
int PageCount = 0;
PdfDictionary PageDictionary = default(PdfDictionary);
PdfArray Annots = default(PdfArray);
//Open our reader
R = new PdfReader(BaseFile);
//Get the page cont
PageCount = R.NumberOfPages;
//Loop through each page
for (int i = 1; i <= PageCount; i++)
{
//Get the current page
PageDictionary = R.GetPageN(i);
//Get all of the annotations for the current page
Annots = PageDictionary.GetAsArray(PdfName.ANNOTS);
//Make sure we have something
if ((Annots == null) || (Annots.Length == 0))
continue;
//Loop through each annotation
foreach (PdfObject A in Annots.ArrayList)
{
//Convert the itext-specific object as a generic PDF object
PdfDictionary AnnotationDictionary = (PdfDictionary)PdfReader.GetPdfObject(A);
//Make sure this annotation has a link
if (!AnnotationDictionary.Get(PdfName.SUBTYPE).Equals(PdfName.LINK))
continue;
//Make sure this annotation has an ACTION
if (AnnotationDictionary.Get(PdfName.A) == null)
continue;
//Get the ACTION for the current annotation
PdfDictionary AnnotationAction = (PdfDictionary)AnnotationDictionary.Get(PdfName.A);
//Test if it is a URI action
if (AnnotationAction.Get(PdfName.S).Equals(PdfName.URI))
{
//Change the URI to something else
AnnotationAction.Put(PdfName.URI, new PdfString("http://www.bing.com/"));
}
}
}
//Next we create a new document add import each page from the reader above
using (FileStream FS = new FileStream(OutputFile, FileMode.Create, FileAccess.Write, FileShare.None))
{
using (Document Doc = new Document())
{
using (PdfCopy writer = new PdfCopy(Doc, FS))
{
Doc.Open();
for (int i = 1; i <= R.NumberOfPages; i++)
{
writer.AddPage(writer.GetImportedPage(R, i));
}
Doc.Close();
}
}
}
}
}
}
EDIT
I should note, this only changes the actual link. Any text within the document won't get updated. Annotations are drawn on top of text but aren't really tied to the text underneath in anyway. That's another topic completely.
Noted if the Action is indirect it will not return a dictionary and you will have an error:
PdfDictionary AnnotationAction = (PdfDictionary)AnnotationDictionary.Get(PdfName.A);
In cases of possible indirect dictionaries:
PdfDictionary Action = null;
//Get action directly or by indirect reference
PdfObject obj = Annotation.Get(PdfName.A);
if (obj.IsIndirect) {
Action = PdfReader.GetPdfObject(obj);
} else {
Action = (PdfDictionary)obj;
}
In that case you have to investigate the returned dictionary to figure out where the URI is found. As with an indirect /Launch dictionary the URI is located in the /F item being of type PRIndirectReference with the /Type being a /FileSpec and the URI located in the value of /F
Added code for dealing with indirect and launch actions and null annotation-dictionary:
PdfReader r = new PdfReader(#"d:\kb2\" + f);
for (int i = 1; i <= r.NumberOfPages; i++) {
//Get the current page
var PageDictionary = r.GetPageN(i);
//Get all of the annotations for the current page
var Annots = PageDictionary.GetAsArray(PdfName.ANNOTS);
//Make sure we have something
if ((Annots == null) || (Annots.Length == 0))
continue;
foreach (var A in Annots.ArrayList) {
var AnnotationDictionary = PdfReader.GetPdfObject(A) as PdfDictionary;
if (AnnotationDictionary == null)
continue;
//Make sure this annotation has a link
if (!AnnotationDictionary.Get(PdfName.SUBTYPE).Equals(PdfName.LINK))
continue;
//Make sure this annotation has an ACTION
if (AnnotationDictionary.Get(PdfName.A) == null)
continue;
var annotActionObject = AnnotationDictionary.Get(PdfName.A);
var AnnotationAction = (PdfDictionary)(annotActionObject.IsIndirect() ? PdfReader.GetPdfObject(annotActionObject) : annotActionObject);
var type = AnnotationAction.Get(PdfName.S);
//Test if it is a URI action
if (type.Equals(PdfName.URI)) {
//Change the URI to something else
string relativeRef = AnnotationAction.GetAsString(PdfName.URI).ToString();
AnnotationAction.Put(PdfName.URI, new PdfString(url));
} else if (type.Equals(PdfName.LAUNCH)) {
//Change the URI to something else
var filespec = AnnotationAction.GetAsDict(PdfName.F);
string url = filespec.GetAsString(PdfName.F).ToString();
AnnotationAction.Put(PdfName.F, new PdfString(url));
}
}
}
//Next we create a new document add import each page from the reader above
using (var output = File.OpenWrite(outputFile.FullName)) {
using (Document Doc = new Document()) {
using (PdfCopy writer = new PdfCopy(Doc, output)) {
Doc.Open();
for (int i = 1; i <= r.NumberOfPages; i++) {
writer.AddPage(writer.GetImportedPage(r, i));
}
Doc.Close();
}
}
}
r.Close();