FontMetrics : Java Glossary

For measuring height, FontMetrics is quite crude. FontMetrics. getAscent, getHeight and getDescent are only approximate, and includes a of 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, you could create a dummy Graphics2D context like this:

...
BufferedImage bufferedImage =
new BufferedImage ( 2 /* dummy */,
                    2 /* dummy */,
                    BufferedImage.TYPE_4BYTE_ABGR_PRE );
Graphics2D g2d = ( Graphics2D)( bufferedImage.createGraphics() );
FontRenderContext fr = g2d.getFontRenderContext();
LineMetrics lm = font.getLineMetrics( sampleText, fr );
float ascent = lm.getAscent();
float descent = lm.getDescent();
float height = lm.getHeight();

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