private void UniteWithBounds(CoordinateTransform transform, Rect bounds)
{
var childViewportBounds = bounds.ScreenToViewport(transform);
if (boundsUnionMode == BoundsUnionMode.Bounds)
overallViewportBounds.Union(childViewportBounds);
else
{
overallViewportBounds.Union(childViewportBounds.GetCenter());
}
}