False Positive Virus Detection

We get notifications about virus detection software that raises a flag on our products from time to time.

Alerts are triggered because specific program code match patterns shared by malicious code. While some anti-virus programs look at the context of the code, others are more prone to raise an alert as soon as a pattern is matched.

Because the programs sometimes use code obfuscation to protect the intellectual property, it is hard for the detection to see the context. On top of that, some viruses are distributed using the same type of obfuscation and therefore producing some of the same code patterns.

Before we release new versions of our programs, we try to scan the release candidates with as many different brands of anti-virus software as possible. We do this to change some of the code to minimize the number of triggered alerts for false positives. However, this is a moving target because the searched patterns change over time.

If you find a detection alert, you are welcome to send us information about it. We will look at it and see if we can change the code signature to prevent it in the future. This will help us improve the software over time.

Our installers are signed with digital certificates to prevent code changes. Make sure that you have checked the signature before you install it. You should generally validate the signature on everything you get via the Internet.

We do not consider it a realistic target to have zero detections across all brands of anti-virus software at all times. If only one or two brands detect something, it may be better to contact them about the triggered event.

Unicode Text Watermarks

The built in watermark text does not support Unicode text. In this example you will see how you can easily create a Japanese watermark text and use it when printing from Notepad. Of course you can also use technique for other languages and when printing from other applications.

First you open a program such as Microsoft Word to produce the watermark with the Unicode text. In Word there is a watermark feature that helps you create diagonal text on your document background. We can use that in this example.

Select the watermark tool from the menu

The Printed Watermark dialog will appear and you can set the watermark properties as you please.

Setting the watermark text, font and color

With the watermark in place you have an empty page with at diagonal text. The next step is to export this Word document to a PDF. You can use the built in export functionality in Word or print it to the PDF printer.

Now that we have the watermark PDF, we can start using it. In this example we have a simple Notepad document that we want to print with the watermark.

Sample document to print with a text watermark

When you print this document to the PDF printer, you must click the Merge tab to specify the watermark PDF file as the background.

Setting the watermark PDF as the printed background

That’s it. You are done. The result will look like this.

The resulting PDF file with the watermark

Control parameters using runonce.ini

The runonce.ini is a configuration file used to set the parameters for the next print job. It is typically used by programmers to specify how a PDF should be created and where it should be saved.

In structure the runonce.ini is a normal ini configuration file with a main section and simple name value pairs in a text file. It can look something like this:

[PDF Printer]
Output=<desktop>\MyPDF-<guid>.pdf
ShowSettings=never
ShowSaveAS=never
ShowProgress=no
ShowProgressFinished=no
ShowPDF=no
ConfirmOverwrite=no

One Job

A runonce configuration is only meant for one print job. When the printer sees a runonce configuration it will read it and delete it, so that it does not affect the next job.

Concurrency

Printing is an asynchronous process where a program places a print job on the print job queue. Job on the print queue is handled by the Windows Spooler process and sent to the individual printers. Therefore, a program cannot know when a specific print job is up for printing. It can send it to the queue but then it is up to the Spooler.

When printing multiple jobs without any pause between the jobs, you risk overriding a previous runonce.ini before it has been picked up by the corresponding print job. There are basically two strategies you can use to avoid this problem.

The first is to wait for your print job to finish before sending the next one. Let’s say that you are a programmer and want to print multiple PDF documents in a loop. In this case it is recommended that you use the statusfile setting to specify a unique status file name for each job. After you have written the runonce configuration and sent the job to the printer, you wait for the status file to appear. When you see the status file, you can read it and move on to the next job. The benefit of waiting for a status file instead of the actual document is that the status file will also be created in case of an error. The other benefit is that the resulting PDF document is completed when the status file is written. If you simply look for the PDF document then it may not be complete when you first see it in the file system.

The second method require that you can control the name of the print job in the printer queue. This is possible from many programming languages but it may not be possible in other systems. If you can set the print job name then you can create a specific runonce configuration that will only be picked up by that particular print job. More information is available here:

https://www.biopdf.com/guide/configuration_files.php

Parallel Printing

In case you need a high throughput of print jobs, you can install multiple printers with dedicated printer ports. You can read more about Printing to multiple virtual printers simultaneously here:

Printing to Multiple Virtual Printers Simultaneously

Terminal Server and Citrix

The runonce configurations are user specific. This means that runonce files from one user does not affect other users on a system with multiple users. This means that it is safe to use on a Terminal Server.

Creating Runonce Files

Given that the runonce is a simple text file, you can use any programming technique for writing text files to create a configuration. The location and character encoding are documented here:

https://www.biopdf.com/guide/configuration_files.php

Instead of writing the configuration files directly, it is recommended that you use the API to do that. The API will know the correct location for the current users on the specific version of Windows. The API is available in both COM and Microsoft.NET versions.

Examples

This is a link to an example of how to use the runonce from code:

https://www.biopdf.com/guide/examples/csharp_auto_convert/

More examples can be found here:

https://www.biopdf.com/guide/index.php

Adding Page Numbers

You can use the watermark feature to add page numbers to the printed document.

Here is a sample of how you can use the <pageno> and <pagecount> macro tags in the watermark text in the options dialog.

These settings will produce an output with page numbers in the lower right corner.

The configuration for watermarks can also be set directly in the configuration files with the following settings:

watermarktext=TEST PAGE NO OF
watermarkfontsize=20
watermarkrotation=90
watermarkcolor=#4F4F4F
watermarkfontname=ARIALNB.TTF
watermarkoutlinewidth=0
watermarklayer=top
watermarkverticalposition=bottom
watermarkhorizontalposition=right
watermarkverticaladjustment=1
watermarkhorizontaladjustment=1

Default PDF Reader

You can choose your default PDF reader by following these simple steps.

  • Right-click a PDF file on your desktop or in File Explorer to bring up the context menu.
  • Click Open with -> Choose another app
  • In the window where you can select an application, you should remember to set the Always use this app to open .pdf files
Use PDF Studio to open your PDF documents

That is all it takes.

Default Save Location

How do you set up the default save location for your PDF documents? This is a common question we get from the users of the PDF printer.

The answer is simple, and the possibilities are endless if you want to do advanced stuff.

First the simple answer

You simply open the Options dialog from the Start menu. In there you change the File Name setting to your preferred location and file name.

When you specify the output path, you can use Macro Tags to make the file name Macro Tags to make the file name a bit more flexible. These tags are substituted with dynamic values that may depend on the current date and time or settings on your specific machine. It can also get information from the print job or even run a script.

The most used tags include <desktop>, which points to the location of the desktop, or <personal>, which is your personal documents folder on the machine.

This is what it looks like:

Setting a default PDF file name

Now, the advanced answer

The macro tags can tap into information such as environment variables, system time, print job information, counters, unique id generation, and running scripts.

You can learn more about these macros at the BioPDF web site.

Information about the default save location is stored in the Output setting in the configuration files.

What about the name of the source document?

Users ask us why there isn’t a macro for the name and location of the source document. For example, this could be the docx file printed from Microsoft Word or a text file in Notepad.

The problem is that we need to know the source document’s file name. Unfortunately, all the printer see is a print job, which does not contain information about its origin. Instead, it has a limited set of properties set by the printing application. These include the author and the document name, but it is entirely up to the printing application to set those to something meaningful, and again, the source file name and location are not among them.

Add a counter or GUID to the PDF file name

If you want the printer to generate file names automatically and have a counter or unique id as part of your file name, this will show you how.

When you open the printer options from the start menu, you can set a file name to use when a print job is created. This file name can contain tags, which are substituted with other values when printing.

Tags can give you information such as timestamps, user names, machine names, and much more. A couple of these tags have functionality for counters and unique id generators.

Here is an example where a counter is used.

Preset a file name with a counter

Every time the printer is used the <counter> tag will increase by one.

You can see a full list of available tags here:

https://www.biopdf.com/guide/macro_tags.php

The list also contains a <random> and a <guid> tag for generating file names with a random part or a GUID (globally unique identifier).

You can add parameters to counter and random tags. It is also possible to have multiple counters and you can preset values for these counters if you like.

Printing to Multiple Virtual Printers Simultaneously

We have been asked by system administrators if it is possible to print to many PDF printers at the same time. It is now. Starting with version 11.14, you can create multiple printer ports during installation. Before this version, the limiting factor was that even if you had multiple virtual printers, they would all use the same virtual printer port. This means that one printer had to wait for the other to finish spooling the print job.

When you install a new PDF printer with a custom name using /PRINTERNAME=”My printer”, you can now add a custom port for this printer. The port is added with /PORT=”MYPORT”. This will give you a printer named My Printer connected to MYPORT. This means that the new printer can spool and print individually from other printers on the same machine.

Example of running the setup to add the new printer:

Setup.exe /PRINTERNAME="My Printer" /PORT="MYPORT" /SILENT

Spooler Options

Another optimization of the printing speed is to change the spooler options to Start printing after last page is spooled. This helps if one print job is taking a long time to finish printing. Usually, the spooling is faster than the printing for the virtual printer.

Start printing after last page is spooled – Advanced Printer Options

One caveat of this option is that if you use the runonce.ini to control the parameters of the print job, you no longer know the order of the print jobs. This means that unless you have unique names for your print jobs the runonce.ini files may not be used with the print jobs they were meant for.

If you can control the names of the print jobs from the printing application, then you can use the runonce_jobname.ini file names to match the print jobs and the configurations.

Fast PDF Printing

The fastest printing is achieved by creating a configuration for the printers that generate automatic file names and disable the printing dialogs so that printing is unattended. On top of that, you should create multiple instances of the printer with different names and individual port names. Spooler settings should be set to start printing after the last page is spooled.

Two large print jobs printing at the same time

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Google Chrome 80 PostScript Error

There is a problem with Chrome 80 and the PostScript passthrough. The bug is confirmed by Google and they are trying to fix it.

https://bugs.chromium.org/p/chromium/issues/detail?id=1030689

The PDF printer version 11.12 contains a fix/workaround for this problem. This means that if you see the following error when printing to PDF then you just upgrade to the newest version.

%%[ ProductName: GPL Ghostscript ]%%
%%[Page: 1]%%%%[Page: 2]%%
%%[ Error: typecheck; OffendingCommand: setlinecap ]%%

If you are interested then you can check this link to see the actual fix that the next version of Chrome will have.

https://pdfium.googlesource.com/pdfium/+/f201c7389829371dcf2bbcc58b38a1910b5856e6%5E%21/#F0

One of our users also reported having seen this problem with the Firefox browser. However, this is not confirmed.