mirroredAbout function
t mirrored in its own frame about box's centre x (D7): the
footprint does not move, a scale is kept.
Implementation
Transform2 mirroredAbout(Transform2 t, SymbolBox box) {
final cx = (box.left + box.right) / 2;
return t
.multiply(Transform2.translation(cx, 0))
.multiply(Transform2.scale(-1, 1))
.multiply(Transform2.translation(-cx, 0));
}