paintOffset method
Computes the portion of the region from from
to to
that is visible.
This method is identical to RenderSliver.calculatePaintOffset.
Implementation
double paintOffset(double from, double to) {
assert(from <= to);
final minOffset = scrollOffset;
final maxOffset = scrollOffset + remainingPaintExtent;
from = from.clamp(minOffset, maxOffset);
to = to.clamp(minOffset, maxOffset);
return (to - from).clamp(0.0, remainingPaintExtent);
}