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.
The default --num-processes is the number of CPUs multiplied by 5,
which seems to give this VM a hard-time. Even the number of CPUs is too
much, so lets use half of that (I’m adding one just in case the division
gives zero).
- 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
Previous priority implementation would move a node further back within it's layer, but at max priority was unable to move any further up than that. This updates the implementation to have 3 priority levels:
1. Distance is reduced by half of table size.
2. Distance is reduced by full table size (move to beginning of the layer).
3. Distance is set to 0. Vertex will be packed as soon as possible.
Also makes the iterative resolutions aware of max priority, so it won't keep trying to raise priority beyond the maximum.
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.
Behdad Esfahbod
Garret Rieger
Khaled Hosny
Qunxin Liu
David Corbett