Java - FontMetrics without Graphics

问题:

How to get FontMetrics without use Graphics ? I want to get FontMetrics in constructor, now I do this way:

BufferedImage bi = new BufferedImage(5, 5, BufferedImage.TYPE_INT_RGB);
FontMetrics fm = bi.getGraphics().getFontMetrics(font);
int width = fm.stringWidth(pattern);
int height = fm.getHeight();

回答1:

Hmm... It is quite logical that you need graphics to get FontMetrics. Font height, width etc. can differ on various displays.

If you have some Component, you can use it for getting FontMetrics:

component.getFontMetrics(font);

回答2:

No you do not necessarily need to get/use the graphics object:

Font font = new Font("Helvetica",Font.PLAIN,12);
Canvas c = new Canvas();
FontMetrics fm = c.getFontMetrics(font);

If you now call c.getGraphics() it will return null. This (canvas) will also work in headless mode.