Draw base line and enclosing line for a font
/*
This program is a part of the companion code for Core Java 8th ed.
(http://horstmann.com/corejava)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JComponent;
import javax.swing.JFrame;
/**
* @version 1.33 2007-04-14
* @author Cay Horstmann
*/
public class FontTest
{
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
FontFrame frame = new FontFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
});
}
}
/**
* A frame with a text message component
*/
class FontFrame extends JFrame
{
public FontFrame()
{
setTitle("FontTest");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
// add component to frame
FontComponent component = new FontComponent();
add(component);
}
public static final int DEFAULT_WIDTH = 300;
public static final int DEFAULT_HEIGHT = 200;
}
/**
* A component that shows a centered message in a box.
*/
class FontComponent extends JComponent
{
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D) g;
String message = "Hello, World!";
Font f = new Font("Serif", Font.BOLD, 36);
g2.setFont(f);
// measure the size of the message
FontRenderContext context = g2.getFontRenderContext();
Rectangle2D bounds = f.getStringBounds(message, context);
// set (x,y) = top left corner of text
double x = (getWidth() - bounds.getWidth()) / 2;
double y = (getHeight() - bounds.getHeight()) / 2;
// add ascent to y to reach the baseline
double ascent = -bounds.getY();
double baseY = y + ascent;
// draw the message
g2.drawString(message, (int) x, (int) baseY);
g2.setPaint(Color.LIGHT_GRAY);
// draw the baseline
g2.draw(new Line2D.Double(x, baseY, x + bounds.getWidth(), baseY));
// draw the enclosing rectangle
Rectangle2D rect = new Rectangle2D.Double(x, y, bounds.getWidth(), bounds.getHeight());
g2.draw(rect);
}
}
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