Function overlay_within 

pub fn overlay_within(
    subject: &OverlayInput,
    clip: &OverlayInput,
    operation: OverlayOperation,
    fill: FillRule,
    options: OverlayOptions,
    execution: &ExecutionOptions,
) -> Result<ReportedOverlay, OverlayRefusal>

overlay_with under the caller’s execution options (#338): the tolerance is ExecutionOptions::tolerance, and with ExecutionOptions::with_memory_budget the subdivision is refused with OverlayRefusal::BudgetExceeded before it would hold more than the budget. Without a budget it is overlay_with exactly, its refusals wrapped in OverlayRefusal::Invalid. An admitted call gives the same result as overlay_with, bit for bit. No other option is read: a cancellation token is not polled.

The charges and their bounds are in the docs of the budget module; a budget covers the subdivision, not the operands or the output.