We Keep Coding

Value already read, or no value when trying to read from a Stream

I've been trying this for a long time but it keeps giving me an error. I have an array of bytes that should represent a nbt document. I would like to convert this into a c# object with a library: fNbt.
Here is my code:
byte[] buffer = Convert.FromBase64String(value);
byte[] decompressed;
using (var inputStream = new MemoryStream(buffer))
{
using var outputStream = new MemoryStream();
using (var gzip = new GZipStream(inputStream, CompressionMode.Decompress, leaveOpen: true))
{
gzip.CopyTo(outputStream);
}
fNbt.NbtReader reader = new fNbt.NbtReader(outputStream, true);
var output = reader.ReadValueAs<AuctionItem>(); //Error: Value already read, or no value to read.
return output;
}
When I try this, it works:
decompressed = outputStream.ToArray();
outputStream.Seek(0, SeekOrigin.Begin);
outputStream.Read(new byte[1000], 0, decompressed.Count() - 1);
But when I try this, it doesn't:
outputStream.Seek(0, SeekOrigin.Begin);
fNbt.NbtReader reader = new fNbt.NbtReader(outputStream, true);
reader.ReadValueAs<AuctionItem>();

NbtReader, like most stream readers, begins reading from the current position of whatever stream you give it. Since you're just done writing to outputStream, then that position is the stream's end. Which means at that point there's nothing to be read.
The solution is to seek the outputStream back to the beginning before reading from it:
outputStream.Seek(0, SeekOrigin.Begin); // <-- seek to the beginning
// Do the read
fNbt.NbtReader reader = new fNbt.NbtReader(outputStream, true);
var output = reader.ReadValueAs<AuctionItem>(); // No error anymore
return output;

The solution is as follows. NbtReader.ReadValueAs does not consider a nbtCompound or nbtList as value. I made this little reader but it is not done yet (I will update the code once it is done).
public static T ReadValueAs<T>(string value) where T: new()
{
byte[] buffer = Convert.FromBase64String(value);
using (var inputStream = new MemoryStream(buffer))
{
using var outputStream = new MemoryStream();
using (var gzip = new GZipStream(inputStream, CompressionMode.Decompress, leaveOpen: true))
{
gzip.CopyTo(outputStream);
}
outputStream.Seek(0, SeekOrigin.Begin);
return new EasyNbt.NbtReader(outputStream).ReadValueAs<T>();
}
}
This is the NbtReader:
private MemoryStream MemStream { get; set; }
public NbtReader(MemoryStream memStream)
{
MemStream = memStream;
}
public T ReadValueAs<T>() where T: new()
{
return ReadTagAs<T>(new fNbt.NbtReader(MemStream, true).ReadAsTag());
}
private T ReadTagAs<T>(fNbt.NbtTag nbtTag)
{
//Reads to the root and adds to T...
}

iText7 Create PDF in memory instead of physical file

How do one create PDF in memorystream instead of physical file using itext7?
I have no idea how to do it in the latest version, any help?
I tried the following code, but pdfSM is not properly populated:
string filePath = "./abc.pdf";
MemoryStream pdfSM = new ByteArrayOutputStream();
PdfDocument doc = new PdfDocument(new PdfReader(filePath), new PdfWriter(pdfSM));
.......
doc.close();
The full testing code as below for your reference, it worked when past filePath into PdfWriter but not for the memory stream:
public static readonly String sourceFolder = "../../FormTest/";
public static readonly String destinationFolder = "../../Output/";
static void Main(string[] args)
{
String srcFilePattern = "I-983";
String destPattern = "I-129_2014_";
String src = sourceFolder + srcFilePattern + ".pdf";
String dest = destinationFolder + destPattern + "_flattened.pdf";
MemoryStream returnSM = new MemoryStream();
PdfDocument doc = new PdfDocument(new PdfReader(src), new PdfWriter(returnSM));
PdfAcroForm form = PdfAcroForm.GetAcroForm(doc, false);
foreach (PdfFormField field in form.GetFormFields().Values)
{
var fieldName = field.GetFieldName();
var type = field.GetType();
if (fieldName != null)
{
if (type.Name.Equals("PdfTextFormField"))
{
field.SetValue("T");
}
}
}
form.FlattenFields();
doc.Close();
}

This works for me.
public byte[] CreatePdf()
{
var stream = new MemoryStream();
var writer = new PdfWriter(stream);
var pdf = new PdfDocument(writer);
var document = new Document(pdf);
document.Add(new Paragraph("Hello world!"));
document.Close();
return stream.ToArray();
}

I needed the same thing. Got it working like this:
(I included some settings which improve performance)
string HtmlString = "<html><head></head><body>some content</body></html>";
byte[] buffer;
PdfDocument pdfDoc = null;
using (MemoryStream memStream = new MemoryStream())
{
using(PdfWriter pdfWriter = new PdfWriter(memStream, wp))
{
pdfWriter.SetCloseStream(true);
using (pdfDoc = new PdfDocument(pdfWriter))
{
ConverterProperties props = new ConverterProperties();
pdfDoc.SetDefaultPageSize(PageSize.LETTER);
pdfDoc.SetCloseWriter(true);
pdfDoc.SetCloseReader(true);
pdfDoc.SetFlushUnusedObjects(true);
HtmlConverter.ConvertToPdf(HtmlString, pdfDoc, props));
pdfDoc.Close();
}
}
buffer = memStream.ToArray();
}
return buffer;

iText7、C# Controller
Error:
public ActionResult Report()
{
//...
doc1.Close();
return File(memoryStream1, "application/pdf", "pdf_file_name.pdf");
}
Work:
public ActionResult Report()
{
//...
doc1.Close();
byte[] byte1 = memoryStream1.ToArray();
return File(byte1, "application/pdf", "pdf_file_name.pdf");
}
I don't know why... but, it's working!
another: link

How to reset the stream of StreamReader to beginning?

I have referred this Return StreamReader to Beginning, but couldn't figure out this problem.
This is code to read stream of a particular file in zip file. Here there are two stream of files inside two different zip files. Now I need to compare the streams.
I am unable to set the stream of BaseFileReader stream to beginning of stream.
using (FileStream BaseZipToOpen = new FileStream(BaseArchive,FileMode.Open) , CurrentZipToOpen = new FileStream(CurrentArchive,FileMode.Open))
{
using (ZipArchive BaseZip = new ZipArchive(BaseZipToOpen, ZipArchiveMode.Read), CurrentZip = new ZipArchive(CurrentZipToOpen, ZipArchiveMode.Read))
{
ZipArchiveEntry BaseFile = BaseZip.GetEntry(requiredFile);
ZipArchiveEntry CurrentFile = CurrentZip.GetEntry(requiredFile);
using (StreamReader BaseFileReader = new StreamReader(BaseFile.Open()), CurrentFileReader = new StreamReader(CurrentFile.Open()))
{
string baseFileLine, currentFileLine;
while (!CurrentFileReader.EndOfStream)
{
currentFileLine = CurrentFileReader.ReadLine();
while (!BaseFileReader.EndOfStream)
{
baseFileLine = BaseFileReader.ReadLine();
if (!currentFileLine.Equals(baseFileLine))
{
difference = true;
}
else
{
difference = false;
break;
}
}
// how to reset BaseFileReader Stream to beginning?
BaseZipToOpen.Seek(0, SeekOrigin.Begin); //This is not working
}
}
}
}

You can use
FileStream stream = new FileStream();
stream.Position = 0;

How to add multiple fpages to fixed document in xps?

My requirement is to create xps document which has 10 pages (say). I am using the following code to create a xps document. Please take a look.
// Create the new document
XpsDocument xd = new XpsDocument("D:\\9780545325653.xps", FileAccess.ReadWrite);
IXpsFixedDocumentSequenceWriter xdSW = xd.AddFixedDocumentSequence();
IXpsFixedDocumentWriter xdW = xdSW.AddFixedDocument();
IXpsFixedPageWriter xpW = xdW.AddFixedPage();
fontURI = AddFontResourceToFixedPage(xpW, #"D:\arial.ttf");
image = AddJpegImageResourceToFixedPage(xpW, #"D:\Single content\20_1.jpg");
StringBuilder pageContents = new StringBuilder();
pageContents.Append(ReadFile(#"D:\Single content\20.fpage\20.fpage", i));
xmlWriter = xpW.XmlWriter;
xmlWriter.WriteRaw(pageContents.ToString());
}
xmlWriter.Close();
xpW.Commit();
// Commit the fixed document
xdW.Commit();
// Commite the fixed document sequence writer
xdSW.Commit();
// Commit the XPS document itself
xd.Close();
}
private static string AddFontResourceToFixedPage(IXpsFixedPageWriter pageWriter, String fontFileName)
{
string fontUri = "";
using (XpsFont font = pageWriter.AddFont(false))
{
using (Stream dstFontStream = font.GetStream())
using (Stream srcFontStream = File.OpenRead(fontFileName))
{
CopyStream(srcFontStream, dstFontStream);
// commit font resource to the package file
font.Commit();
}
fontUri = font.Uri.ToString();
}
return fontUri;
}
private static Int32 CopyStream(Stream srcStream, Stream dstStream)
{
const int size = 64 * 1024; // copy using 64K buffers
byte[] localBuffer = new byte[size];
int bytesRead;
Int32 bytesMoved = 0;
// reset stream pointers
srcStream.Seek(0, SeekOrigin.Begin);
dstStream.Seek(0, SeekOrigin.Begin);
// stream position is advanced automatically by stream object
while ((bytesRead = srcStream.Read(localBuffer, 0, size)) > 0)
{
dstStream.Write(localBuffer, 0, bytesRead);
bytesMoved += bytesRead;
}
return bytesMoved;
}
private static string ReadFile(string filePath,int i)
{
FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.ReadWrite);
StringBuilder sb = new StringBuilder();
using (StreamReader sr = new StreamReader(fs))
{
String line;
// Read and display lines from the file until the end of
// the file is reached.
while ((line = sr.ReadLine()) != null)
{
sb.AppendLine(line);
}
}
string allines = sb.ToString();
//allines = allines.Replace("FontUri=\"/Resources/f7728e4c-2606-4fcb-b963-d2d3f52b013b.odttf\"", "FontUri=\"" + fontURI + "\" ");
//XmlReader xmlReader = XmlReader.Create(fs, new XmlReaderSettings() { IgnoreComments = true });
XMLSerializer serializer = new XMLSerializer();
FixedPage fp = (FixedPage)serializer.DeSerialize(allines, typeof(FixedPage));
foreach (Glyphs glyph in fp.lstGlyphs)
{
glyph.FontUri = fontURI;
}
fp.Path.PathFill.ImageBrush.ImageSource = image;
fs.Close();
string fpageString = serializer.Serialize(fp);
return fpageString;
}
private static string AddJpegImageResourceToFixedPage(IXpsFixedPageWriter pageWriter, String imgFileName)
{
XpsImage image = pageWriter.AddImage("image/jpeg");
using (Stream dstImageStream = image.GetStream())
using (Stream srcImageStream = File.OpenRead(imgFileName))
{
CopyStream(srcImageStream, dstImageStream); // commit image resource to the package file
//image.Commit();
}
return image.Uri.ToString();
}
If you see it, i would have passed single image and single fpage to create a xps document. I want to pass multiple fpages list and image list to create a xps document which has multiple pages..?

You are doing this in the most excruciatingly difficult manner possible. I'd suggest taking the lazy man's route.
Realize that an XpsDocument is just a wrapper on a FixedDocumentSequence, which contains zero or more FixedDocuments, which contains zero or more FixedPages. All these types can be created, manipulated and combined without writing XML.
All you really need to do is create a FixedPage with whatever content on it you need. Here's an example:
static FixedPage CreateFixedPage(Uri imageSource)
{
FixedPage fp = new FixedPage();
fp.Width = 320;
fp.Height = 240;
Grid g = new Grid();
g.HorizontalAlignment = System.Windows.HorizontalAlignment.Center;
g.VerticalAlignment = System.Windows.VerticalAlignment.Center;
fp.Children.Add(g);
Image img = new Image
{
UriSource = imageSource,
};
g.Children.Add(image);
return fp;
}
This is all WPF. I'm creating a FixedPage that has as its root a Grid, which contains an Image that is loaded from the given Uri. The image will be stretched to fill the available space of the Grid. Or, you could do whatever you want. Create a template as a UserControl, send it text to place within itself, whatever.
Next, you just need to add a bunch of fixed pages to an XpsDocument. It's incredibly hard, so read carefully:
public void WriteAllPages(XpsDocument document, IEnumerable<FixedPage> pages)
{
var writer = XpsDocument.CreateXpsDocumentWriter(document);
foreach(var page in pages)
writer.Write(page);
}
And that's all you need to do. Create your pages, add them to your document. Done.

iTextSharp file manipulation and display to FileStreamResults

I am trying top open a PDF file using iTextSharp, add a dataset to the file to prepopulate data, then save it to a stream so that I can display it to the users. I don't want to save it locally to a file. I keep getting the error "Cannot access a closed Stream." I can't figure out which stream is wrong.
Here is my code:
public FileStreamResult PushDataIntoPDFStream(string filename)
{
var reader = new PdfReader(Path.Combine(Server.MapPath(path), filename));
var xml = #"<?xml version=""1.0"" encoding=""UTF-8""?>
<form1>
<firstName>test</firstName>
<lastName>user</lastName>
<driveCar>0</driveCar>
<gender>1</gender>
<birthdate>2011-08-12</birthdate>
<numPets>4</numPets>
</form1>";
using (var outstream = new MemoryStream())
{
using (var stamper = new PdfStamper(reader, outstream))
{
var bytes = System.Text.Encoding.UTF8.GetBytes(xml);
using (var ms = new MemoryStream(bytes))
{
stamper.AcroFields.Xfa.FillXfaForm(ms);
}
}
return new FileStreamResult(outstream, "application/pdf")
{
FileDownloadName = "file.pdf";
};
}
}

The PdfStamper has a .CloseStream property on its internal output stream; try setting it to false:
using (var stamper = new PdfStamper(reader, outstream))
{
stamper.Writer.CloseStream = false;