Reporting - Generate Accessible PDF Documents (v21.1)

Among all DevExpress Reports export formats, PDF is the most popular. In v21.1, we enhanced our PDF export engine and now allow you to generate tagged (accessible) PDF documents from apps that rely on DevExpress Reports. This post describes PDF accessibility, why it is important, and how you can generate accessible PDF documents. 

Accessible PDF Document Formats

PDF/A

PDF/A is a file format based on PDF. ‘A’ stands for Archiving. This standard defines the requirements one must meet to preserve a PDF document’s visual appearance over time. This standard consists of several sections.

PDF/A-1: The first part of the PDF/A standard. It was published in 2005. It is based on PDF v1.4. The standard requires all PDF document resources (such as images, graphic content, and characters) to be embedded within the document.

PDF/A-2: The second part of the standard. It is based on PDF 1.7. This standard was created in 2011 to make new features of PDF 1.7 available for PDF/A compatible documents. This means that PDF/A-2 allows for JPEG2000 compression, transparent elements, PDF layers. Another important addition is that PDF/A files can be embedded within a PDF/A-2 document.

PDF/A-3, which was created in 2012, added one more new feature to PDF/A-2: the ability to add arbitrary file types as attachments.

All these standards have so-called conformance levels. The first level is denoted as ‘b’, which stands for Basic. This level only ensures that a document’s visual appearance is preserved over the long term. The next level, which is based on ‘b’, is denoted as ‘a’. This means Accessible. This level ensures that a document’s logical structure matches a natural reading order. This makes the document accessible for people with disabilities, for example visually impaired individuals.

PDF/UA

The PDF/UA (Universal Accessibility) standard was created in 2012. This standard is similar to PDF/A Conformance Level A documents. The standard formulates requirements for document structure such that the document is accessible for people with disabilities, for example partially sighted people. The difference between the PDF/A Conformance Level A and PDF/UA is that PDF/UA adds specific demands on the semantic structure of PDF documents. These demands are built upon established concepts for accessible web content (WCAG 2.0).

Here are some of the requirements the standard defines for PDF documents:

• Content is categorized in one of two ways: meaningful content, and artifacts such as decorative page elements. All meaningful content must be tagged and integrated into the structure tree of all tags within a document. Artifacts, on the other hand, need only be marked as such.
• The structure tree generated by document tags must reflect the document’s logical reading order.
• Any pictorial elements – whether image objects or other non-text objects such as vector objects or object groups – must have a corresponding alternative text.

The primary objective of these requirements is to allow screen readers to read information from PDF files.

DevExpress PDF Export Engine

In v21.1, you can export your DevExpress report documents to accessible PDF documents (we now support PDF/A-1a, PDF/A-2a, PDF/A-3a, and PDF/UA standards):

Please refer to the following help topics for more information in this regard:

• PDF/A Compatibility;
• PDF/UA Compatibility.

We also added a new Accessible Description property for report controls. This property allows you to specify the text a screen reader can vocalize instead of the control’s default content:

Currently, this property works for accessible PDF documents (PDF/A-1a, PDF/A-2a, PDF/A-3a, and PDF/UA) generated from reports and for Web Document Viewers that support accessibility. Note that this property is bindable. This means that you can specify an expression for this property and also bind it to a data source field.

So, how can one verify that an exported PDF document meets accessibility requirements?

One possible option is to use Adobe Acrobat Pro. You can open a PDF document in the app and then verify whether the document is accessible. The following example displays verification results for our sample invoice report:

Another option is to use PDF Accessibility Checker (PAC). It allows you to determine whether your PDF document conforms to the PDF/UA standard. Here are the PAC3 results for our sample invoice report:

Your Feedback Matters

We’d love to know what you think of PDF Accessibility support within DevExpress Reports. Please share your accessibility related thoughts/use case below.

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