resolveExtraSize method

@override Size resolveExtraSize(Size size, double t, { bool isRoot = true, })

The amount of space (per axis) freed by this transform for a backdrop of size at progress t. Returns Size.zero when nothing is freed.

Implementation

@override
Size resolveExtraSize(Size size, double t, {bool isRoot = true}) {
  final scale = scaleAt(t);
  final sizeAfterScale = Size(size.width * scale, size.height * scale);
  if (isRoot) {
    // The root layer divides by the scale factor so the freed space maps back
    // into the un-scaled coordinate space of the drawer that fills it. Clamp
    // to zero: at low t the division can produce a small negative value, but
    // the backdrop never frees negative space.
    return Size(
      max(0.0, size.width - sizeAfterScale.width / minScale),
      max(0.0, size.height - sizeAfterScale.height / minScale),
    );
  }
  return Size(
    max(0.0, size.width - sizeAfterScale.width),
    max(0.0, size.height - sizeAfterScale.height),
  );
}