Text flow within a bounded region, and across several of them.

flow_text/7 fills one box and reports what did not fit. flow_across_boxes/4 threads a single body of text through a list of boxes in order, which is how multi-column layouts work: each column is a box, and text continues into the next when one fills.

columns = [{50, 700, 240, 600}, {310, 700, 240, 600}]

{pdf, result} = Box.flow_across_boxes(pdf, rich_text, columns, line_height: 14)

if result.overflow? do
  # result.spill_text is what did not fit in any box
end

Boxes are {x, y, width, height} in PDF user space, with y at the box's top edge — text flows downward from there.

Tagging

In a tagged document the flowed text is marked up as a /P. Two options control that:

• :tag — :auto (the default) tags only when the document is already being tagged, true always, false never
• :tag_as — the structure element, :p by default. Pass :artifact for decoration.

:artifact matters more than it looks. A watermark, a running strapline or a repeated sidebar label is text a reader should skip, and marking it /P means it is announced on every page — worse than not tagging at all. Structure that is well-formed but wrong is the failure a conformance checker cannot see for you.

# Announced as content.
Box.flow_text(pdf, x, y, w, h, body)

# Skipped, correctly.
Box.flow_text(pdf, x, y, w, h, watermark, tag_as: :artifact)