StackOverflow2013

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copied!<p>A very simple example of a swing component to draw lines. It keeps internally a list with the lines that have been added with the method addLine. Each time a new line is added, repaint is invoked to inform the graphical subsytem that a new paint is required.</p> <p>The class also includes some example of usage.</p> <pre><code>import java.awt.BorderLayout; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.LinkedList; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JPanel; public class LinesComponent extends JComponent{ private static class Line{ final int x1; final int y1; final int x2; final int y2; final Color color; public Line(int x1, int y1, int x2, int y2, Color color) { this.x1 = x1; this.y1 = y1; this.x2 = x2; this.y2 = y2; this.color = color; } } private final LinkedList<Line> lines = new LinkedList<Line>(); public void addLine(int x1, int x2, int x3, int x4) { addLine(x1, x2, x3, x4, Color.black); } public void addLine(int x1, int x2, int x3, int x4, Color color) { lines.add(new Line(x1,x2,x3,x4, color)); repaint(); } public void clearLines() { lines.clear(); repaint(); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); for (Line line : lines) { g.setColor(line.color); g.drawLine(line.x1, line.y1, line.x2, line.y2); } } public static void main(String[] args) { JFrame testFrame = new JFrame(); testFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); final LinesComponent comp = new LinesComponent(); comp.setPreferredSize(new Dimension(320, 200)); testFrame.getContentPane().add(comp, BorderLayout.CENTER); JPanel buttonsPanel = new JPanel(); JButton newLineButton = new JButton("New Line"); JButton clearButton = new JButton("Clear"); buttonsPanel.add(newLineButton); buttonsPanel.add(clearButton); testFrame.getContentPane().add(buttonsPanel, BorderLayout.SOUTH); newLineButton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { int x1 = (int) (Math.random()*320); int x2 = (int) (Math.random()*320); int y1 = (int) (Math.random()*200); int y2 = (int) (Math.random()*200); Color randomColor = new Color((float)Math.random(), (float)Math.random(), (float)Math.random()); comp.addLine(x1, y1, x2, y2, randomColor); } }); clearButton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { comp.clearLines(); } }); testFrame.pack(); testFrame.setVisible(true); } } </code></pre>

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