This is needed to ensure virtual link ordering constraints are respected when repack is being called from fontTools. For subset usage, repack won't be called if the graph doesn't already overflow so this change doesn't cause any extra work.
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.
isolate_subgraph can change the root indices in some cases. So operations after the isolation need to use the roots from the output of isolate_subgraph.
- Presize the output sorted graph and write it once in the correct order to avoid needing to reverse.
- Swap the old/new graph vectors instead of copying.
- Use a boolean vector for tracking visited instead of a set.
Assign each connected component that is underneath one or more 32 bit offsets into a unique space. This ensures that 32 bit subgraphs which are connected are packed into the same space.
Prior to this fix id remapping at the end of the isolation operation was fed the old subgraph instead of the new one. Which results in object indices being remapped for the nodes outside of the new subgraph. Adds a test which detects this problem.
- Detect cases where there are multiple links from a parent to a child. Don't duplicate that child if those are the only remaining links to the child.
- Correctly handle isolating a subgraph where the root idx has multiple incoming links.
Each subgraph pointed to by a 32 bit offset should be packed into it's own space. This adds a space property to vertices which affects the distance calculation. This effectively places the distances for all of the nodes of a 32 bit subgraph into a distinct range. Thus all of the nodes of the subgraph will be packed together.
If a node is duplicated during isolation then any children it has will have incoming links from outside the subgraph (from the duplicated node and the original node), so they must be duplicated too.
Garret Rieger
Behdad Esfahbod
Qunxin Liu
luz paz