Fixes https://oss-fuzz.com/testcase-detail/5549945449480192
In prune_langsys: move LangSys visited check up before any work is done for a LangSys. In this particular case the compare() method is responsible for the majority of the time spent and wasn't being guarded with a visisted check.
- When pos_glyphs is empty, use current full glyphs set as input for
subsequent recursive closure process
- Also increase max_lookup_visit_count to 35000 cause a real font file hit
previous limit 20000 and some lookups are dropped unexpectedly
Ligature subtables use virtual links to enforce an ordering constraint between the subtables and the coverage table. Unfortunately this has the sideeffect of prevent the subtables from being shared by another Ligature with a different coverage table since object equality compares all links real and virtual. This change makes virtual links stored separately from real links and updates the equality check to only check real links. If an object is de-duped any virtual links it has are merged into the object that replaces it.
The current CMAP4 implementation uses whatever the current codepoint ranges are and then encodes them as indivudal glyph ids or as a delta if possible. However, it's often possible to save bytes by splitting up existing ranges and encoding parts of them using deltas where the cost of splitting the range is less than encoding each glyph individual.
We implicitly require it for building ragel subproject. This new version
requirement should satisfied in both Fedora 33 and Debian bullseye, and
not be too cutting edge for us.
Though the spec said FeatureRecords are sorted alphabetically by feature
tag, there're font files with unsorted FeatureList. And harfbuzz is not
able to subset these files correctly because we use binary search in
finding featureRecords when collecting lookups. Also
find_duplicate_features needs to be updated to handle this.
In Windows 7 on Chrome if the coverage table comes before any of the LigatureSet or Ligature subtables the font won't load. This changes the packing order to always place the Coverage table last. Virtual links are used to ensure the repacker maintains the desired ordering.
Coincidentally fontTools also does the same thing (a3f988fbf6/Lib/fontTools/ttLib/tables/otTables.py (L1137)) to reduce overflows during packing.
ArrayOf.serialize_append allocates space for the new item, but ArrayOf.pop() does not recover the allocated space. So in the case where the revert path was entered the extra space added by serialize_append gets left in the serialization buffer. This moves the snapshot to before ArrayOf.serialize_append is called so that revert cleans up the buffer extend.
Behdad Esfahbod
Khaled Hosny
Simon Cozens
luz paz
Garret Rieger
Qunxin Liu
Matthias Clasen
David Corbett