import java.awt.geom.*;

static void paintFitBackground(Component c, Graphics _g, BufferedImage image) {
  Graphics2D g = cast _g;
  RenderingHints hints = g.getRenderingHints();
  antiAliasOn(g);
  int w = c.getWidth(), h = c.getHeight();
  g.setColor(c.getBackground());
  g.fillRect(0, 0, w, h);
  if (image != null) {
    int iw = image.getWidth(), ih = image.getHeight();
    double imgScale = max(doubleRatio(h, ih), doubleRatio(w, iw));
    AffineTransform before = g.getTransform();
    double y1 = h-ih*imgScale;
    g.scale(imgScale, imgScale);
    g.translate(iround((w-iw*imgScale)/2), iround((h-ih*imgScale)/2));
    g.drawImage(image, 0, 0, c);
    g.setTransform(before);
  }
  g.setRenderingHints(hints);
}

Began life as a copy of #1015864