PDFlib 8 Windows COM/.NET Tutorial

Table 10.17 Operations which are recommended for generating Tagged PDF
item
Recommended PDFlib functions and options for Tagged PDF compatibility
Unicode mappings Provide alternate text for symbols via the ActualText or Alt options of begin_item( ).
hyphenation
word boundaries
artifacts
Type 3 font
properties
interactive elements
Word breaks (separating words in two parts at the end of a line) should be presented using a soft
hyphen character (U+00AD) as opposed to a hard hyphen (U+002D)
Words should be separated by space characters (U+0020) even if this would not strictly be required
for positioning. The autospace parameter can be used for automatically generating space
characters after each call to one of the show functions.
In order to distinguish real content from page artifacts, artifacts should be identified as such using
begin_item( ) with tag=Artifact.
The familyname, stretch, and weight options of begin_font( ) should be supplied with reasonable
values for all Type 3 fonts used in a Tagged PDF document.
Interactive elements, e.g. links, should be included in the document structure and made accessible
if required, e.g. by supplying alternate text. The tab order for interactive elements can be
specified with the taborder option of begin/end_document( ) (this is not necessary if the interactive
elements are properly included in the document structure).
10.5.2 Creating Tagged PDF with direct Text Output and Textflows
Minimal Tagged PDF sample. The following sample code creates a very simplistic
Tagged PDF document. Its structure tree contains only a single P element. The code uses
the autospace feature to automatically generate space characters between fragments of
text:
if (p.begin_document("hello-tagged.pdf", "tagged=true") == -1)
throw new Exception("Error: " + p.get_errmsg());
/* automatically create spaces between chunks of text */
p.set_parameter("autospace", "true");
/* open the first structure element as a child of the document structure root (=0) */
id = p.begin_item("P", "Title={Simple Paragraph}");
p.begin_page_ext(0, 0, "width=a4.width height=a4.height");
font = p.load_font("Helvetica-Bold", "unicode", "");
p.setfont(font, 24);
p.show_xy("Hello, Tagged PDF!", 50, 700);
p.continue_text("This PDF has a very simple");
p.continue_text("document structure.");
p.end_page_ext("");
p.end_item(id);
p.end_document("");
Generating Tagged PDF with Textflow. The Textflow feature (see Section 8.2, »Multi-
Line Textflows«, page 207) offers powerful features for text formatting. Since individual
text fragments are no longer under client control, but will be formatted automatically
by PDFlib, special care must be taken when generating Tagged PDF with textflows:
> Textflows can not contain individual structure elements, but the complete contents
of a single Textflow fitbox can be contained in a structure element.
270 Chapter 10: PDF Versions and Standards (Edition for COM, .NET, and REALbasic)