static double calcFitScale(BufferedImage image, Component c) {
  ret calcFitScale(image, c.getWidth(), c.getHeight());
}

static double calcFitScale(BufferedImage image, int w, int h default w) {
  int iw = image.getWidth(), ih = image.getHeight();
  ret max(doubleRatio(h, ih), doubleRatio(w, iw));
}

Began life as a copy of #1019468