Graphics and Java 2D - Java: How to Program Early Objects - page 582

Line 25 of Fig. 13.29 casts the Graphics reference received by paintComponent to a
Graphics2D reference and assigns it to g2d to allow access to the Java 2D features.

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// Fig. 13.29: ShapesJPanel.java

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// Demonstrating some Java 2D shapes.

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import java.awt.Color;

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import java.awt.Graphics;

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import java.awt.BasicStroke;
import java.awt.GradientPaint;
import java.awt.TexturePaint;

import java.awt.Rectangle;

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import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;
import java.awt.geom.Arc2D;
import java.awt.geom.Line2D;
import java.awt.image.BufferedImage;

import javax.swing.JPanel;

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public class ShapesJPanel extends JPanel

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{

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// draw shapes with Java 2D API

21 @Override

22 public void paintComponent(Graphics g)

23 {

24 super.paintComponent(g);

25 Graphics2D g2d = (Graphics2D) g; // cast g to Graphics2D

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27 // draw 2D ellipse filled with a blue-yellow gradient

g2d.setPaint( new GradientPaint( 5 , 30 , Color.BLUE , 35 , 100 ,
Color.YELLOW , true ));
g2d.fill( new Ellipse2D.Double( 5 , 30 , 65 , 100 ));

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32 // draw 2D rectangle in red

g2d.setPaint( Color.RED );
g2d.setStroke( new BasicStroke( 10.0f ));
g2d.draw( new Rectangle2D.Double( 80 , 30 , 65 , 100 ));

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37 // draw 2D rounded rectangle with a buffered background

BufferedImage buffImage = new BufferedImage( 10 , 10 ,
BufferedImage.TYPE_INT_RGB );

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41 // obtain Graphics2D from buffImage and draw on it

42 Graphics2D gg = buffImage.createGraphics();

43 gg.setColor( Color.YELLOW );

44 gg.fillRect( 0 , 0 , 10 , 10 );

45 gg.setColor( Color.BLACK );

46 gg.drawRect( 1 , 1 , 6 , 6 );

47 gg.setColor( Color.BLUE );

48 gg.fillRect( 1 , 1 , 3 , 3 );

49 gg.setColor( Color.RED );

Fig. 13.29 | Demonstrating some Java 2D shapes. (Part 1 of 2.)