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Editing XPS Print Spool Files(.SPL Extension) in C# (Saving as Zip Problem)

When someone print a document(with XPS printing path) I want to pause print job and edit SPL(which zipped XPS format) file.
If I edit the file with 7zip and save. If I resume the job that document printing without any problem.
If I open the SPL file with System.IO.Compression.ZipFile class or DotNetZip library or SevenZipSharp library and extract a file from SPL file & remove that filefrom SPL file and add that file again to SPL file it generates perfectly fine zip container. I compared the original SPL file and edited SPL file with 7zip, zipinfo, winrar tools and I didn't see any difference. All files in the container are exactly same. I also checked CRCs.
When I'm opening,editing and saving the zipfile I'm not changing anything about compression method, compression level and etc. As I said two zip files looks like exactly same but If I calculate CRCs of original and edited SPL files they are not same.
After I edited(just extracting a page file, deleting it from container and adding it again to container) If I try to resume print job I see an error in event viewer about PrintProcessor and I can't print it.
I can't figure out what's changing after I edit the file(not changing anything in container). I'm going crazy.
Is there any specification about the Zip format of SPL files?

Problem solves If I use "ZipPackage" class.
using (var pack = ZipPackage.Open(xpsFileName, FileMode.Open, FileAccess.ReadWrite))
{
foreach (var part in pack.GetParts()) if (part.Uri.OriginalString.EndsWith(".fpage"))
{
using (var file = part.GetStream(FileMode.Open, FileAccess.ReadWrite))
{
var page = ProcessPage(XElement.Load(file));
file.Position = 0;
page.Save(file);
file.SetLength(file.Position);
}
}
}

Open workbook in Interop.Excel from byte array

I want to open Excel from byte[] because my file is encrypted and I want to open after decrypt but without write in a file.
The office has "restricted access" and I want to open my file with this protection but without saving the decrypted content in a file.
myApp.Workbooks.Open only supports a path.
Is it possible?

As an alternative to OpenXml there's also ExcelDataReader which from my experience is a lot faster in processing data compared to Interop.Excel(around 3 times+).
It can also open encrypted Excel files directly(stackoverflow)
The github page for ExcelDataReader has some great examples on how to use it. The only thing you'd have to do is:
This:
using (var stream = File.Open(filePath, FileMode.Open, FileAccess.Read))
Becomes this:
using (var stream = new MemoryStream(yourByte[])
And if you just want to open the password protected excel file you'd do this:
var conf = new ExcelReaderConfiguration { Password = "yourPassword" }; //Add this
excelReader = ExcelReaderFactory.CreateReader(stream, conf); //change the excel Reader to this
Make sure to check the Github page for more info!

It is not possible because the interop is actually an interface for programs to run and operate existing excel on the computer.
I think you need to use openxml created by Microsoft to work with excel word and PowerPoint.
DocumentFormat.OpenXml
Then you can use:
ExcelPackage excelPackage = new ExcelPackage(stream)
or
var pck = new OfficeOpenXml.ExcelPackage();
pck.Load(File.OpenRead(path));
pck.Load(Stream) can use any stream as input not only from a file.
It depends on your needs.

Fast way to add a single file to a large ZIP file using C#

I have a large zip file (let's say 10 GB), to which I want to add a single small file (let's say 50 KB). I'm using the following code:
using System.IO.Compression;
using (var targetZip = ZipFile.Open(largeZipFilePath), ZipArchiveMode.Update)
{
targetZip.CreateEntryFromFile(smallFilePath, "foobar");
}
While this works (eventually), it takes a very long time and consumes a ludicrous amount of memory. It seems to extract and recompress the whole archive.
How can I improve this in .Net 4.7? Solution without external dependencies is preferred, but not required if impossible.

use visual studio nuget package manager and install that
Install-Package DotNetZip -Version 1.11.0
using (ZipFile zip = new ZipFile())
{
zip.AddFile("ReadMe.txt"); // no password for this one
zip.Password= "123456!";
zip.AddFile("7440-N49th.png");
zip.Password= "!Secret1";
zip.AddFile("2005_Annual_Report.pdf");
zip.Save("Backup.zip");
}
https://www.nuget.org/packages/DotNetZip/

Since you are in above .NET 4.5, you can use the ZipArchive (System.IO.Compression) class to achieve this. Here is the MSDN documentation: (MSDN).
Here is their example, it just writes text, but you could read in a .csv file and write it out to your new file. To just copy the file in, you would use CreateFileFromEntry, which is an extension method for ZipArchive.
using (FileStream zipToOpen = new FileStream(#"c:\users\exampleuser\release.zip", FileMode.Open))
{
using (ZipArchive archive = new ZipArchive(zipToOpen, ZipArchiveMode.Update))
{
ZipArchiveEntry readmeEntry = archive.CreateEntry("Readme.txt");
using (StreamWriter writer = new StreamWriter(readmeEntry.Open()))
{
writer.WriteLine("Information about this package.");
writer.WriteLine("========================");
}
}
}
Check this:- https://stackoverflow.com/a/22339337/9912441
https://learn.microsoft.com/en-us/dotnet/standard/io/how-to-compress-and-extract-files

I found the reason for this behaviour in another Stack Overflow answer: Out of memory exception while updating zip in c#.net.
The gist of it is that this takes a long time because ZipArchiveMode.Update caches the zip file into memory. The suggestion for avoiding this caching behaviour is to create a new archive, and copy the old archive contents along with the new file to it.
See the MSDN documentation which explains how ZipArchiveMode.Update behaves:

DotNetZip Library read from one zip into another

Using the DotNetZip Library (http://dotnetzip.codeplex.com/) is there a way to move files from one zip file into another without extracting that file to disk first? Maybe extract to a stream, then update into the other zip from that same stream?
The zip files are password protected and the data in these zip files are meant to stay that way due to their licenses. If I simply extract to disk first then update the other zip there is a chance where those files can be intercepted by the user.

Yes, you should be able to do something like;
var ms = new MemoryStream();
using (ZipFile zip = ZipFile.Read(sourceZipFile))
{
zip.Extract("NameOfEntryInArchive.doc", ms);
}
ms.Seek(0);
using (ZipFile zip = new ZipFile())
{
zip.AddEntry("NameOfEntryInArchive.doc", ms);
zip.Save(zipToCreate);
}
(see it as pseudocode since I didn't have a chance to compile)
Naturally you'll have to add your decryption/encryption to that, but those calls are equally straight forward.

Problem in using Ionic.Zip namspace

I am using Ionic.zip to zip up the files.
You consider there are 2 files in c:\img\a.txt and b.txt. When zip up these files as following
using (ZipFile zip = new ZipFile())
{
zip.AddItem(#"F:\imp\a.txt");
zip.AddItem(#"F:\imp\b.txt");
zip.AddItem(#"F:\imp\lookup.ini");
zip.AddItem(#"F:\imp\lookups.mdb");
zip.Save("Lookups.zip");
}
It is creating lookups.zip file correctly. But the problem is content of zip file is...
there is one directory named as imp and it is contains those 2files.
But i do not need of the directory entry only i need files which i added.
Please help me.

As shown in the documentation, use the overload which accepts two strings - one for the directory in the zip file:
using (ZipFile zip = new ZipFile())
{
zip.AddItem(#"F:\imp\a.txt", "");
zip.AddItem(#"F:\imp\b.txt", "");
zip.AddItem(#"F:\imp\lookup.ini", "");
zip.AddItem(#"F:\imp\lookups.mdb", "");
zip.Save("Lookups.zip");
}
(That looks like 4 files to me, not 2, and in imp rather than img... but never mind.)