TermBuf::Damage
Stability: internal
Which cells have changed since the last paint, tracked as one column span per row.
A span rather than a per-cell bitmap because the paint loop walks rows
anyway, and rather than a whole-row flag because a status line that changes
three characters should not cost a full row of output. The row count lets
#any? answer without scanning, so a paint with nothing to do is free.
Constructors
Instance methods
Resizes to height rows, discarding any spans: a resize forces a full repaint, so there is nothing worth carrying over.
The changed columns of row y, or nil when the row is clean.