float fontSize = 96;
contentStream.setFont(font, fontSize);
String text = "OVERLAY";
//float sw = font.getStringWidth(text);
//Too bad, base 14 fonts don't return character metrics.
PDRectangle crop = page.findCropBox();
float cx = crop.getWidth() / 2f;
float cy = crop.getHeight() / 2f;
AffineTransform transform = new AffineTransform();
transform.translate(cx, cy);
transform.rotate(Math.toRadians(45));