fitGridLaidOutRowCount function
Number of rows currently laid out.
Assert on this to prove virtualization is working: it should track the viewport, not the dataset. A grid of 100,000 rows in a 600px viewport should report tens, not tens of thousands.
Implementation
int fitGridLaidOutRowCount({int index = 0}) {
final section = fitGridSection(index: index);
return (section.firstVisibleRow + section.visibleRowCount).clamp(
0,
section.rowCount,
) -
section.firstVisibleRow;
}