Hacktoberfest 2026: los issues que los mantenedores marcaron para octubre, abiertos y aptos para principiantes. Explorar issues de Hacktoberfest

CI: catch tofu and wrong-glyph regressions — check that emitted fonts survive OTS and that the pdf output paints the right glyphs

Abierto
  • ¿Algo no está bien?
#765 0 comentarios 0 reacciones 0 asignados Ver en GitHub

Los mantenedores suelen responder en 1 día

Nadie ha tomado este issue todavía.

Evaluación

Dificultad
5/5
Tiempo estimado
Más de una semana
Aptitud para principiantes
35/100
Tipo de issue
Nueva funcionalidad
Claridad
Bastante claro
Estado de actividad
Tranquilo
Stack tecnológico
cpp, github-actions, python
Área
backend, ci-cd, testing

Línea de trabajo

Start with the test job in .github/workflows/build_test.yml, alongside the existing html-tidy and compare-html steps, and inspect test/scripts/ for how checks are run locally. The proposal calls for OTS validation of emitted font blobs and an allow-listed PDF text comparison; first decide which checks and oracle approach to implement. Done means deterministic CI checks fail on the described regressions and can also be run locally.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

devops enhancement

Embedded-font regressions in the pdf output have shipped repeatedly and were
always found by eye, never by CI:

  • #613 — TrueType subsets without a name table: OTS rejects the font, the
    @font-face is dropped, every PUA glyph renders as tofu.
  • #660 — three at once: a CFF Name INDEX holding a space makes OTS discard
    the table; passing OpenType Layout / device-metric tables through verbatim
    makes one malformed table reject the whole font; and a leaked PUA cmap made
    the second output of a document paint whole runs with the wrong glyphs.
  • #702 — subset producers name glyphs gidNNNNN, which no glyph list
    translates, so those runs fell through to code-as-GID and painted unrelated
    glyphs.
  • #749, #752, #753 — the same family of "the text is there, it just isn't the
    right shapes / isn't where it should be".

Two distinct failure modes, both invisible to the current pipeline:

  1. The browser refuses the font. font_is_usable
    (src/odr/internal/html/pdf_file.cpp:2773) only probes that our own encode
    path does not throw. Whether OTS — the sanitizer in every browser, far
    stricter than FreeType or fontTools — accepts the bytes we then emit is
    never checked anywhere.
  2. The font loads but paints the wrong glyphs. Nothing compares the shapes
    actually painted against what the page says the text is.

build-test does render the corpus, but the comparison is against
test/data/reference-output, which is regenerated wholesale from our own
output — a bug that is already in the reference is invisible, and #660 in fact
sat there. The pdf views also screenshot nondeterministically (a control run
flaps ~1/60 files), so a genuine small regression is easy to wave off as noise.

Proposal

Two cheap, deterministic checks. Neither needs the reference output, so neither
can be papered over by regenerating it.

1. Every emitted font must survive OTS

After odr_test writes build/test/output/**, extract every
data:font/...;base64 blob from the generated html and run ots-sanitize over
it (pip install opentype-sanitizer ships the binary; it is what I reach for
by hand every time one of these lands). Any ERROR fails the job, and the
message names the exact rejection reason.

This is seconds of runtime, no browser, no flakiness, and it catches #613 and
two thirds of #660 directly.

Worth considering as the stronger version: pull ots in as a test-only conan
dependency and assert it inside odr_test, over the corpus in
test/src/internal/font/. That turns it into a unit-level guard on
SfntFont::write / cff::wrap_to_otf rather than a post-pass over html, and
it fails on the developer's machine before the push.

2. The glyphs painted must be the glyphs meant

For the pdf corpus, take the text an oracle extracts from the source pdf
(gs -sDEVICE=txtwrite, or pdftotext) and compare it against the text of the
generated html, normalised for whitespace. That is the check that would have
caught the PUA-cmap leak in #660 and the gidNNNNN fallthrough in #702: the
page still renders, the layout is unchanged, only the shapes are wrong — and
because we re-encode to the PUA, the html's text is the thing that stays
correct while the glyphs drift, so a text-level oracle sees the divergence the
screenshot comparison shrugs at.

Start with a small allow-listed set of pdf files with a stable expected text,
rather than the whole corpus, so the check is meaningful before it is complete.

A cheaper complement, if the browser is already up: assert in-page that
document.fonts reports every declared face loaded and that no run measures
at the fallback's advance — that catches "the font was dropped" from the other
side, without an oracle.

Where it goes

test job in .github/workflows/build_test.yml, next to the existing
html-tidy / compare-html steps, and mirrored in a script under
test/scripts/ so it is runnable locally the same way.

Lenguaje dominante
C++
Estrellas
41
Forks
10
Merge medio
12 h 4 min
PR fusionados (30 d)
297

Preparar el entorno

Este proyecto no incluye contenedor de desarrollo, Dockerfile ni guía de contribución, así que la configuración corre por tu cuenta: empieza por su README y consulta nuestra guía para la primera contribución para los pasos generales.

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Más de opendocument-app/OpenDocument.core

Todos los issues de opendocument-app/OpenDocument.core

Issues similares

Más issues de C++

Recibe los nuevos issues en tu correo

Un resumen breve de issues de GitHub para principiantes.