Drawing an image and send it to another class

Short answer: use a BufferedImage to transfer the graphics.

Long answer:

import java.awt.*;

import java.awt.event.*;

import java.awt.geom.Line2D;

import java.awt.image.BufferedImage;

import java.util.*;

import java.util.List;

import javax.swing.*;

public class SendingLines implements ActionListener {

SendingLinesPanel linePanel;

JLabel label;

public void actionPerformed(ActionEvent e) {

String ac = e.getActionCommand();

if(ac.equals("ADD LINE"))

linePanel.addLine();

if(ac.equals("TRANSFER"))

transferLines();

}

private void transferLines() {

// Make image of the component.

int w = linePanel.getWidth();

int h = linePanel.getHeight();

int type = BufferedImage.TYPE_INT_RGB;

BufferedImage image = new BufferedImage(w, h, type);

Graphics2D g2 = image.createGraphics();

// Have linePanel draw itself into this image.

linePanel.paint(g2);

g2.dispose();

// Set the image in local label.

label.setIcon(new ImageIcon(image));

}

private JPanel getCenterPanel() {

linePanel = new SendingLinesPanel();

linePanel.setBorder(BorderFactory.createEtchedBorder());

label = new JLabel();

label.setHorizontalAlignment(JLabel.CENTER);

label.setBorder(BorderFactory.createEtchedBorder());

JPanel panel = new JPanel(new GridLayout(1,0));

panel.add(linePanel);

panel.add(label);

return panel;

}

private JPanel getLast() {

String[]ids = { "add line", "transfer" };

JPanel panel = new JPanel();

for(int j = 0; j < ids.length; j++) {

JButton button = new JButton(ids[j]);

button.setActionCommand(ids[j].toUpperCase());

button.addActionListener(this);

panel.add(button);

}

return panel;

}

public static void main(String[] args) {

SendingLines test = new SendingLines();

JFrame f = new JFrame();

f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

f.getContentPane().add(test.getCenterPanel());

f.getContentPane().add(test.getLast(), "Last");

f.pack();

f.setLocation(200,200);

f.setVisible(true);

}

}

class SendingLinesPanel extends JPanel {

List<Line2D.Double> lines = new ArrayList<Line2D.Double>();

Random seed = new Random();

protected void paintComponent(Graphics g) {

super.paintComponent(g);

Graphics2D g2 = (Graphics2D)g;

g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,

RenderingHints.VALUE_ANTIALIAS_ON);

for(Line2D line : lines)

g2.draw(line);

}

public Dimension getPreferredSize() {

return new Dimension(300,300);

}

public void addLine() {

int w = getWidth();

int h = getHeight();

int x1 = seed.nextInt(w);

int y1 = seed.nextInt(h);

int x2 = seed.nextInt(w);

int y2 = seed.nextInt(h);

lines.add(new Line2D.Double(x1, y1, x2, y2));

repaint();

}

}

crwooda at 2007-7-12 9:38:16 >