sicher
released this
2026-10-22 15:13:15 +02:00
| 0 commits to main since this release
Added
- Continuing styled text across regions:
WriteResult.resume_at (a
TextPosition: word index plus byte offset, where writing stopped) and
ParagraphOptions.start. Call writeStyled again with the same
StyledText and start = resume_at to continue in the next column or page with
every span and style intact. Before, the only continuation was
overflow, which for styled text holds just the rest of one span -
later spans were silently lost.
platen.Path: the path builder type returned by doc.createPath() is
now exported, so helpers can take a *platen.Path.- Complete GSUB: every lookup type - single, multiple, alternate,
ligature, context (formats 1-3), chained context (formats 1-3),
extension, reverse chained - with lookup flags (ignore base glyphs /
ligatures / marks, mark attachment classes, mark filtering sets, via
GDEF), applied in lookup-list order over the whole run as HarfBuzz does,
for any feature. Before, only single, ligature and chained context
format 3 lookups were read, each wired to a few features. New default
features, as in HarfBuzz: ccmp, locl, rlig, clig (turn off with
setFeature). ccmp gives dotless i/j under accents (Gentium, Inter:
j́, ị́, Lithuanian į́) and joins emoji ZWJ sequences, skin tones
and flags into one glyph (Noto Color Emoji).
- Default ignorables are removed: U+FE0F/U+FE0E, ZWJ, ZWNJ, zero-width
space, soft hyphen, word joiner, BOM and the other Default_Ignorable code
points no longer draw (U+FE0F was .notdef in Noto Color Emoji, a soft
hyphen passed to writeAt a visible hyphen) and add no width. During
GSUB they are skipped where HarfBuzz skips them - ZWJ always, ZWNJ only
in context - so keycaps (1️⃣), ❤️ and 🏳️🌈 join, f+ZWJ+i still
ligates and ZWNJ still blocks ligatures. Their code points stay out of
extracted text.
- Variation sequences (cmap format 14): a character followed by a
variation selector draws as the glyph the font lists for the pair - CJK
ideograph variants, text-style emoji with U+FE0E in Noto Emoji - as
HarfBuzz does; unlisted selectors are dropped as before. font-info
shows whether a font has them.
- CLI
shape <font> [+feat|-feat]...: glyph IDs for each stdin line, as
rendering shapes it.
Fixed
- Shaping differed from HarfBuzz (found by the new differential
test): Inter's <-> became <- plus >, case together with tnum
gave tabular but not case forms (features ran in a fixed order, not the
font's lookup order), and Satoshi's frac gave no numerators or
denominators.
- CFF fonts lost contextual alternates: a subset of a
.otf font kept
only the first glyph drawn for each character, so a contextual variant
of a character already drawn plainly (Inter's raised hyphen in A-B
after a-b) rendered as .notdef. Every drawn glyph is kept now, as for
TrueType.
- Translucent color-font gradients painted opaque: COLRv1 gradient
stops carry an alpha, which was dropped, so overlays meant to fade out
covered the glyph - Noto's rainbow flag 🏳️🌈 came out grey, and about
2,000 Noto Color Emoji glyphs had such gradients. Stop alpha is now
drawn through a soft mask (or /ca when it is constant).
- A color glyph without an outline painted the whole page: Bungee
Spice's space is a color glyph whose clip glyph has no contours; the
empty clip was written as W n with no path, which sets no clip, so its
gradient covered the page from that point on. Such paints are now
skipped (an empty clip shows nothing).
- Underlines and strikethroughs ran into the space a line wraps at
(write()): the line was drawn with its trailing space, and the
decoration with it. The space now hangs past the line end, as in CSS,
also when it ends one write() call and the next call's first word
wraps; spaces inside the line stay decorated.
write() lost text before a double space: line batching reset
the line at every space it skipped, so write("aa bb") drew only
"bb" (at aa's place), and a call starting with a space mid-line lost
it (" over" after "jumps" gave "jumpsover"). Spaces inside a line
are kept as typed now.- SVG hairlines were rounded: stroke widths were written with two
decimals in SVG units (the tiger's 0.172 became 0.17); now four.
- Bitmap-only fonts had an empty
FontBBox: an OTB pixel font's head
box is 0 wide, so every glyph fell outside its Type3 font's box
(poppler warned on each). Such fonts now get [0 0 0 0], which tells
viewers to make no assumptions about glyph sizes.
- Color emoji ligatures extracted as U+FFFD: the Type3 ToUnicode of
a color font mapped only single code points, so a joined emoji (ZWJ
family, flag, keycap) copied as a replacement character. It maps to the
whole sequence now.
- Text extraction of substituted glyphs: ToUnicode now follows the
shaped glyphs' clusters - a ligature maps to its characters, a glyph a
multiple substitution produced to its own character of the
decomposition - instead of re-guessing ligatures after shaping.
- Words wider than the line lost their end at a region boundary: a
word broken over lines (soft hyphens, regular hyphens, or between
characters) that reached the bottom of the region was cut off and
layout went on with the next word. Writing now stops mid-word and
resume_at carries the byte offset, so the next region continues the
word (lines are the unit, as in TeX and CSS fragmentation). Pieces are
measured in the span's own style (bold words were broken with regular
widths).
- Knuth-Plass put a too-wide word on one endless line: with
.line_breaking = .optimal, a word wider than the line made every
break infeasible and the whole paragraph came out as a single line
running past the region. Such a word now gets a line of its own and is
broken into pieces, as with greedy breaking.
measure_only drew broken words: measuring a paragraph containing
a word wider than the line drew that word's pieces on the page.- Combining marks compose to the font's precomposed glyphs: a base
followed by combining marks (e.g. i + U+0308) was drawn as separate
glyphs positioned by GPOS - or simply overprinted in fonts without mark
positioning - giving a dotted i under a diaeresis. Like HarfBuzz,
shaping now composes the sequence into the precomposed character
(U+00EF) when the font has a glyph for it; otherwise it stays
decomposed. Measurement and rendering share the decoding, and the
ToUnicode text of such a glyph is the sequence as typed.
- Unused fonts were embedded whole: a font loaded into a document but
never drawn with (only measured, or not used at all) has no glyphs to
subset, so output() wrote the complete original font file as orphan
objects - 25 MB for Noto Color Emoji. Only fonts some page draws with
are written now.
- Justified text in embedded Unicode fonts: lines set in a single
style were justified only through the PDF Tw operator, which applies
to the single-byte code 32 and never to 2-byte Identity-H codes (nor to
color-font runs), so those lines came out ragged in every
.identity font. The extra word space is now emitted after each space
glyph as a TJ adjustment (or Tm offset in the mark-positioning
path), and Tw is 0 for these runs (poppler applies it to the 2-byte
code 0x0020 anyway, e.g. a ligature subset to CID 32). New fpdf2
reference justify_embedded.
char_spacing in runs with combining marks: runs with GPOS mark
positioning place every glyph with Tm, so Tc never applied and the
text came out unspaced while measureStyled included the spacing. The
spacing is now added per glyph in that path.char_spacing leaked into later text: a run with non-zero
char_spacing set the PDF Tc operator but never reset it, and Tc
survives ET, so every later text run on the page was letter-spaced
too, while layout measured it without the spacing (overlapping spans,
text overrunning its region). The run now resets Tc before ET.- Gradient stops are copied:
addLinearGradient/addRadialGradient
kept a pointer to the caller's stops slice until output(); stops in
a stack frame that had returned were read after free (garbage colors or
a panic). The document now keeps its own copy.
Internal
- GSUB differential test:
test/shaping/harfbuzz.txt holds HarfBuzz's
glyphs for Latin, diacritic, default-ignorable and emoji texts in Inter,
Satoshi, Gentium, Bungee, Charter and Noto Emoji under several feature
sets (HarfBuzz removing default ignorables, as platen does), plus a synthetic font
with one scenario per lookup type and flag
(scripts/gen_gsub_test_font.py); scripts/gen_shaping_reference.py
regenerates it.
zig build test -Dtest-filter=NAME runs only matching tests.- The 19 references platen generates itself (color fonts, SVG,
decorations, line breaking, transforms, diacritics) are now also
compared rendered, pixel for pixel (compare_pdfs.py --compare-render,
poppler): the text-and-position comparison missed drawing changes.
Seven had drifted - three from bugs fixed here (color_v1_gradient had
the page-filling space baked in), the rest from intended changes
(svg_embedding predated per-path stroke widths: its tiger had 3x
thick whisker outlines).
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