static double areaRoot(Rect r) {
  ret r == null ? 0 : sqrt(area(r));
}

static double areaRoot(DoubleRect r) {
  ret r == null ? 0 : sqrt(area(r));
}

ifclass WidthAndHeight
static double areaRoot(WidthAndHeight img) {
  ret img == null ? 0 : sqrt(area(img));
}
endif

static double areaRoot(BufferedImage img) {
  ret img == null ? 0 : sqrt(area(img));
}

Began life as a copy of #1032160