Using the Mako Core SDK to modify documents in Microsoft’s Universal Print

Over the past year, Microsoft has been working hard to bring its new Cloud printing service, Universal Print, to general availability.

As a part of Universal Print, developers get access to a set of Graph APIs that allows analysis and modification of print job payload data. This feature enables a few different scenarios, including adding security (e.g. redactions or watermarks) to a Universal Print-based workflow.

As a curious engineer, I wanted to see how different it would be for an independent software vendor (ISV) to use our Mako™ Core SDK to modify a print job flowing through Universal Print, instead of using a more traditional route of using a virtual printer driver.

Thinking about the workflow a little more, I came up with the following design:

Using the Mako SDK to modify documents in Universal Print.
Using the Mako SDK to modify documents in Universal Print.

In the design above, we can see the end-user’s Word document gets printed to a virtual printer. This allows the ISV to be notified of the job, and modify it accordingly using Mako. Once modified, the ISV then redirects the job on to the physical printer for printing.

There’s a couple of nice things about this design:

Firstly, it uses the Graph API to access Universal Print, which is an easy-to-use and well documented REST API. Secondly, since the functionality is accessed via a REST API, it allows our ISV service to be written in whichever Mako supported language we like.

I chose C# to make best use of the C# Graph API SDK.

Developing the service

There are five main steps to developing the service:

  1. Handle print job notifications
  2. Download the print job payload
  3. Modify the payload
  4. Upload the payload
  5. Redirect to the target printer

Handle print job notifications

To be notified of print jobs in Universal print, you can use the Graph’s change notifications. These will allow you to sign up to a notification, which will call a provided webhook.

Download the print job payload

Once we have notification that a print job has been sent to our virtual printer, we can start downloading its payload.

Here we use the appropriate Graph APIs, along with standard Graph authentication to access the print job’s document. We then simply save it to disk.

Modify the payload

Once we have the document on disk (although Mako can also modify streams too!), we can open the document and modify it using Mako’s document object model (DOM).

Alternatively, Mako can also convert from one page description language (PDL) to another. This is useful in situations where your destination printer doesn’t support the input PDL.

Upload the payload

Uploading the modified document is straightforward. This time we use the Graph API to create an upload session, and use the WebClient class to put the document back into the original print job.

Redirect to the target printer

And finally, after the print job has been updated, we can redirect it onto another printer. This redirection also automatically completes the print job and task.

Alternatively, if we want to be a little more green, we could always send the document to OneDrive, Sharepoint, or another document management system. After doing so, you then complete the print job and its associated task.

See it in action

We actually coded this demo live in our last Mako webinar, showing an implementation where an ISV wants to automatically redact content.

Access the code directly at our GitHub repository or watch the webinar recording below:

Try it out

We’re keen to talk to you about your Universal Print project and see how we can help. Contact us here.

For more information about Mako, visit globalgraphics.com/mako.

About the author

Andy Cardy, Principal Engineer at Global Graphics Software
Andy Cardy, Principal Engineer at Global Graphics Software

Further reading:

  1. Carry out complex tasks for your print workflow easily with Mako
  2. Improving PDF accessibility with Structure Tagging

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Live coding with Mako Core

Last week, my colleague David Stevenson and I ignored all common sense and ran a live coding demo using Mako™. What could have gone wrong!?

Mako is a software development kit that can be used to add a variety of functions into software products, which is why it’s often referred to as the software engineer’s Swiss Army knife.

During the demo we showed how to use Mako to modernize your print infrastructure in three simple ways:

Firstly, we looked at modernization through library consolidation and showed how you can operate on multiple PDLs including PDF, PCL, PostScript® and XPS, all using a single Mako SDK library. We then looked at adopting automated workflows with Mako and demonstrated how to analyze and redact text automatically in a PDF, using Mako’s layout analysis and text search capabilities. Finally, we showed how you can make the most of print infrastructure-as-a-service by integrating Mako with Microsoft’s Universal Print, including modifying and redirecting print jobs.

Thankfully, nothing did go wrong and if you missed it, don’t worry. We recorded everything and you can watch the recording on demand here:

Also, feel free to watch some of our other past webinars on our YouTube channel to find out more about the Mako SDK.

For more information about Mako, visit globalgraphics.com/mako

Further reading

  1. Carry out complex tasks for your print workflow easily with Mako
  2. Improving PDF accessibility with Structure Tagging

About the author

Andy Cardy, Principal Engineer at Global Graphics Software
Andy Cardy, Principal Engineer at Global Graphics Software

To be the first to receive our blog posts, news updates and product news why not subscribe to our monthly newsletter? Subscribe here

Follow us on LinkedInTwitter, and YouTube

Improving PDF accessibility with Structure Tagging

In this week’s post, Global Graphics Software’s principal engineer, Andrew Cardy, explores the structure tagging API in the Mako™ Core SDK. This feature is particularly valuable as it allows developers to create PDFs that can be read by screen readers, such as Jaws®. This helps blind or partially sighted users unlock the content of a PDF.  Here, Andy explains how to use the structure tagging API in Mako to tag both text and images:

What can we Structure Tag?

Before I begin, let’s talk about PDF: PDF is a fixed-format document. This means you can create it once, and it should (aside from font embedding or rendering issues) look identical across machines. This is obviously a great thing for ensuring your document looks great on your user’s devices, but the downside is that some PDF generators can create fixed content that is ordered in a way that is hard for screen readers to understand.

Luckily Mako also has an API for page layout analysis. This API will analyze the structure of the PDF, and using various heuristics and techniques, will group the text on the page together in horizontal runs and vertical columns. It’ll then assign a page reading order.

The structure tagging API makes it easy to take the layout analysis of the page and use it to tag and structure the text. So, while we’re tagging the images, we’ll tag the text too!

Mako’s Structure Tagging API

Mako’s structure tagging API is simple to use. Our architect has done a great job of taking the complicated PDF specification and distilling it down to a number of useful APIs.

Let’s take a look at how we use them to structure a document from start to finish:

Setting the Structure Root

Setting the root structure is straight forward. Firstly, we create an instance of IStructure and set it in the document.

Next we create an instance of a Document level IStructureElement and add that to the structure element we’ve just created.

One thing that I learnt the hard way, is that Acrobat will not allow child structures to be read by a screen reader if their parent has alternative (alt) text set.

Add alternate text only to tags that don’t have child tags. Adding alternate text to a parent tag prevents a screen reader from reading any of that tag’s child tags. (Adobe Acrobat help)

Originally, when I started this research project, I had alt text set at the document level, which caused all sorts of confusion when my text and image alt text wasn’t read!

Using the Layout Analysis API

Now that we’ve structured the document, it’s time to structure the text. Firstly, we want to understand the layout of the page. To do this, we use IPageLayout. We give it a reference to the page we want to analyze, then perform the analysis on it.

Now the page has been analyzed, it’s easy to iterate through the columns and nodes in the page layout data.

Tagging the text

Once we’ve found our text runs, we can tag our text with a span IStructureElement. We append this new structure element to the parent paragraph created while we were iterating over the columns.

We also tag the original source Mako DOM node against the new span element.

Tagging the images

Once the text is structured, we can structure the images too.

Earlier, I used Microsoft’s Vision API to take the images in the document and give us a textual description of them. We can now take this textual description and add it to a figure IStructureElement.

Again, we make sure we tag the new figure structure element against the original source Mako DOM image.

Notifying Readers of the Structure Tags

The last thing we need to do is set some metadata in the document’s assembly, this is straight forward enough. Setting this metadata helps viewers to identify that this document is structure tagged.

Putting it all Together

So, after we’ve automated all of that, we now get a nice structure, which, on the whole, flows well and reads well.

We can see this structure in Acrobat DC:

And if we take a look at one of the images, we can see our figure structure now has some alternative text, generated by Microsoft’s Vision API. The alt text will be read by screen readers.

Figure properties dialogue
Figure properties dialogue

It’s not perfect, but then taking a look at how Adobe handles text selection quite nicely illustrates just how hard it is to get it right. In the image below, I’ve attempted to select the whole of the title text in Acrobat.

Layout analysis is hard to get right!

In comparison, our page layout analysis seems to have gotten these particular text runs spot on. But how does it fair with the Jaws screen reader? Let’s see it in action!

Struture tagging with Mako SDK

So, it does a pretty good job. The images have captions automatically generated, there is a sense of flow and most of the content reads in the correct order. Not bad.

Printing accessible PDFs

You may be aware that the Mako SDK comes with a sample virtual printer driver that can print to PDF. I want to take this one step further and add our accessibility structure tagging tool to the printer driver. This way, we could print from any application, and the output will be accessible PDF!

In the video below I’ve found an interesting blog post that I want to save and read offline. If I were partially sighted, it may be somewhat problematic as the PDF printer in Windows 10 doesn’t provide structure tagging, meaning that the PDF I create may not work so well with my combination of PDF reader and screen reader. However, if I throw in my Mako-based structure and image tagger, we’ll see if it can help!

Structure tagging video

Of course, your mileage will vary and the quality of the tagging will depend on the quality and complexity of the source document. The thing is, structural analysis is a hard problem, made harder sometimes by poorly behaving generators, but that’s another topic in itself. Until all PDF files are created perfectly, we’ll do the best we can!

Want to give it a go?

Please do get in touch if you’re interested in having a play with the technology, or just want to chat about it.

Andy Cardy, Principal Engineer at Global Graphics Software
Andy Cardy, Principal Engineer at Global Graphics Software

Andy Cardy is a Principal Engineer for Global Graphics Software and a Developer Advocate for the Mako SDK.

Find out more about Mako’s features in Andy’s coding demo:

SHARPEN THE SAW – A LIVE CODING DEMO USING MAKO™

Sharpen the Saw: Mako SDK demo

In this session Andy uses coding in C++ and C# to show you three complex tasks that you can easily achieve with Mako:
• PDF rendering – visualizing PDF for screen and print (15 mins)
• Using Mako in Cloud-ready frameworks (15 mins)
• Analyzing and editing with the Mako Document Object Model (15 mins)

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Mako™ 5.0 offers a wealth of new features

We’ve recently released Mako™ 5.0, the latest edition of Global Graphics Software’s digital document SDK. Mako 5.0 earns its major version increment with an upgrade to its internal RIP, new features and a reworked API to simplify implementation. Much requested by Mako customers, Mako 5.0 is the first version to preview C# as a coding alternative to C++ and opens the possibility to support other programming languages in future versions.

Mako 5.0 enables PostScript® (including EPS) files to be read directly, extending the PDL (page description language) support in Mako that already includes PDF, XPS, PCL5 and PCL/XL. Mako can read and write all these PDLs, enabling bi-directional conversion between any of these formats.

With the update of Mako’s internal RIP has come new EDS (error diffusion screens) using algorithms such as Floyd-Steinberg and Stucki. All the screening parameters are exposed via this API, and to help define them, a Windows-based desktop tool can be downloaded from the Mako documentation site. Start with settings that match the popular algorithms and preview the monochrome or color result of your settings tweaks. Then use the settings you have chosen via a button that generates the C++ you need to paste into your code.

Mako 5.0 offers several new APIs that extend its reach into the internals of PDF. For example, it’s now possible to edit property values attached to form and image XObjects. Why is this useful? In PDF, developers can put extra key-value pairs into PDF XObject dictionaries. This is often used to store in application-specific data, as well as for things like variable data tags. This development has led to a more generalized approach to examining and modifying hard-to-reach PDF objects. As ever, well-commented sample code is provided to show exactly how the new APIs work and could be applied in your application.

Finally, we took the opportunity with Mako 5.0 to make changes aimed at making the APIs more consistent in their naming, behavior or return types. Developers new to Mako will be unaware of these changes, but existing code written for Mako 4.x may require minor refactoring to work with Mako 5.0. Our support engineers are ready to assist Mako customers with any questions they have.

For more information contact David Stevenson: david.stevenson@globalgraphics.com

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