int const N = min (position.x + other->size().width, size().width) - position.x;
for (int ty = position.y, oy = 0; ty < size().height && oy < other->size().height; ++ty, ++oy) {
int const N = min (position.x + other->size().width, size().width) - position.x;
for (int ty = position.y, oy = 0; ty < size().height && oy < other->size().height; ++ty, ++oy) {