zoom property
The factor the sheet is painted at, where 1.0 is 100%.
Zooming changes only how much of the sheet is visible: content keeps its natural dimensions, so a taller logical viewport at 50% reveals more rows rather than stretching them, and rowHeightBuilder / columnWidthBuilder are never asked for scaled sizes. A builder that wants to react to zoom can read zoomController instead.
Ignored when zoomController is supplied.
Implementation
final double zoom;