Re: FontMetrics help needed

From:

Knute Johnson <nospam@rabbitbrush.frazmtn.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 17 Aug 2006 19:55:08 -0700

Message-ID:

<tZ9Fg.40191$k54.33931@newsfe11.phx>

David Cogen wrote:

Hi, this seems like a "chicken and egg" problem, but I am sure there is
a way to do this:

In order to compute the height of a JPanel I want to instantiate I need
to know the height of a line of text, which I could do using
JPanel.getGraphics().getFontMetrics().getHeight().

But that doesn't work until I call JPanel.setVisible() (null pointer
exception).

But before I can make it visible I need to know its size!

Any suggestions?

Very easy if you can use 1.5 or later.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class test3 extends JPanel {
     String str = "Now is the time for all good men to come to the aid";
     int height;

     public test3(Font font) {
         setFont(font);
         FontMetrics fm = getFontMetrics(font);
         height = fm.getHeight();
         int width = fm.stringWidth(str);
         setPreferredSize(new Dimension(width,height));
     }

     public void paintComponent(Graphics g) {
         g.drawString(str,0,height);
     }

     public static void main(String[] args) {
         Runnable r = new Runnable() {
             public void run() {
                 test3 t3 = new test3(new Font("Arial",Font.BOLD,24));
                 JFrame f = new JFrame();
                 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                 f.add(t3,BorderLayout.CENTER);
                 f.pack();
                 f.setVisible(true);
             }
         };
         EventQueue.invokeLater(r);
     }
}

--

Knute Johnson
email s/nospam/knute/