FontMetrics returns wrong height

Question

I want to get the exact height of my string in pixels on my panel. So I wrote a program that draws the string, and then draws a rectangle around it.

Using FontMetrics I used the getStringBounds method to get me the enclosing rectangle.

However it looks wrong :

I was expecting the rectangle to perfectly enclose my text, but there is space at the top (And a tiny bit of space on the left and right). Why is it giving me this result?

Here is my code :

public class Test extends JPanel {

    @Override
    protected void paintComponent(Graphics g) {

        Font font = new Font("Arial", Font.PLAIN, 60);
        g.setFont(font);

        FontMetrics fm = this.getFontMetrics(font);

        String str = "100dhgt";
        Rectangle2D rect = fm.getStringBounds(str, g);

        int x = 5;
        int y = 100; 

        g.drawRect(x, y - (int)rect.getHeight(), (int)rect.getWidth(), (int)rect.getHeight());
        g.drawString(str, x, y);
    }

    public static void main(String[] args) {
        JFrame f = new JFrame();

        Test test = new Test();
        f.add(test);
        f.setVisible(true);
        f.setSize(400, 400);
    }

}

score 5 · Accepted Answer · answered Apr 07 '16 at 13:27

Regarding your rectangle, you have to consider the font's descend (how far is it below the line)

g.drawString(str, x, y - fm.getDescent());

Also note that the font height usually considers some kind of line spacing. In this case fm.getDescent() + fm.getAscent() = 68 whereas fm.getHeight() = 70

score 2 · Answer 2 · answered Apr 07 '16 at 13:26

2

The space at the top can be explained by your not taking account of the descent (which takes me back to one of my favorite methods from java 1.0: getMaxDecent)

Otherwise, the box looks pretty good. The only other advice I can offer is that fm.getStringBounds works better with some fonts than it does with others

answered Apr 07 '16 at 13:26

ControlAltDel

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Also consider `TextLayout`, examined [here](http://stackoverflow.com/a/16014525/230513). – trashgod Apr 07 '16 at 13:43
so the bounds are a bit like writing text on lined paper? Ie. like in school where you had to write the g and y under the line. – Oliver Watkins Apr 07 '16 at 13:50

FontMetrics returns wrong height

2 Answers2