FontMetrics : Java Glossary

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FontMetrics
To find out how many pixels some text will take on the screen you need FontMetrics.stringWidth(String). The trick is you cannot use the FontMetrics( Font f ) constructor to get your FontMetrics object. You must use the Component.getFontMetrics(Font f) or the Graphics.getFontMetrics( Font f ) method. Unfortunately, you can’t get the FontMetrics object from the Font class alone, and then cache it along with the Font.

For measuring height, FontMetrics is quite crude. FontMetrics. getAscent, getHeight and getDescent are only approximate, and includes a lot of white space. getHeight even includes the suggested leading to the next line.

For more accuracy, you need LineMetrics with takes a sample string of text and a FontRenderingContext. Even it so, it still includes a lot of white space. I don’t know if there is a way to get totally tight bounding box around some text, without rolling your own pixel based methods. LineMetrics is awkward to use. To get a dummy Graphics for FontMetrics, you could try Component. getGraphics(). If you are inside a paintComponent method, you can cast the Graphics object to a Graphics2D. If there is no GUI (Graphic User Interface), you could create a dummy Graphics2D context like this:

Learning More

Oracle’s Javadoc on FontMetrics class : available:
Graphics.getFontMetrics() gets you the FontMetrics of the current Font of the Graphics object.
Oracle’s Javadoc on Graphics.getFontMetrics() : available:
Oracle’s Javadoc on Component.getFontMetrics(Font font) : available:
Canvas
drawing text around its visual centre
example of text centering code
Font
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