Text drawn in rendering mode 3 (3 Tr), which is how a scanned page carries
its recognized OCR text, was left out on open (since #2988, with a warning),
so a scanned PDF opened and saved again lost its searchable text.
Import: an invisible glyph now comes in as type with neither fill nor
stroke. It skips the glyph-outline checks that guard how visible type looks,
and it joins only other invisible text on a line (Look::takes no longer
lets it into a stroke-only run). INVISIBLE_TEXT_NOTE now only reports text
that can't be type (text opened as outlines, Type 3 fonts), and
tests_reader_compat::invisible_text_is_reported_when_left_out expects the
invisible line as unpainted type when text opens as type.
Export and print: characters with no fill and no stroke are written as real
text inside a form marked Mark::Invisible; forms::finish sets that form's
text rendering mode to 3, so it draws nothing but stays selectable and
searchable (PDF/X-1a and PDF/A-2b too). The writer has no invisible mode of
its own, so this reuses the marked-form mechanism used for layers and
overprint.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The visible line's text comes in as type and the invisible line's doesn't; as type or outlines,
all the art kept lies on the visible line's baseline, none on the invisible one's.
Text in rendering mode 3 (invisible: a scanned page's searchable OCR layer) was dropped with no
warning, so a scanned PDF opened and saved again lost its searchable text without a hint. The
import now reports INVISIBLE_TEXT_NOTE when it leaves such text out, for type and outlines alike.
Keeping the text needs a kind of type that is kept but not drawn, and the PDF writer (krilla, in
craft-libs) to write it with `3 Tr`; its text API has fill, stroke and fill-and-stroke only.
