Function inflate_region 

pub fn inflate_region(
    tx: &mut Transaction<'_>,
    options: &InflateOptions,
    region: &[VertexId],
) -> Result<InflateReport>

inflate over the candidates in region, with its cost following them instead of the mesh: the same vertices move to the same positions, bit for bit, as long as region is ascending and holds every vertex under the brush that is used by a triangle. Candidates outside the brush, or dead, are ignored.

Errors

As for inflate, and OpsError::InvalidInput without an incidence index (Mesh::ensure_incidence before the transaction, and no topology edit in it). Nothing is written in any of these cases.