我想在 JPanel 中画一条线。 这是我的 GUI，我希望 JPanel 中有一条白色的线。
我找到了很多例子，但问题是如何使用它。
在许多示例中，他们总是在从 JPanel 扩展的 JFrame 中绘制。
我想将面板添加到框架中，并添加一些按钮以在多个方向上绘制线条，并使用中心的 X 按钮来清理 JPanel。
这是接口的代码：
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.Color;
import javax.swing.JScrollPane;
import javax.swing.JLabel;
import javax.swing.ImageIcon;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
public class circuit extends JFrame {
private JPanel contentPane;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
circuit frame = new circuit();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public circuit() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 559, 332);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setBounds(10, 21, 359, 255);
contentPane.add(scrollPane);
JPanel panel = new JPanel();
scrollPane.setViewportView(panel);
panel.setBackground(Color.WHITE);
JLabel label = new JLabel("New label");
label.addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent arg0) {
/////////////
}
});
label.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\up.png"));
label.setBounds(447, 66, 46, 48);
contentPane.add(label);
JLabel label_1 = new JLabel("New label");
label_1.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\down.png"));
label_1.setBounds(447, 159, 46, 48);
contentPane.add(label_1);
JLabel label_2 = new JLabel("New label");
label_2.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\right.png"));
label_2.setBounds(495, 112, 46, 48);
contentPane.add(label_2);
JLabel label_3 = new JLabel("New label");
label_3.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\left.png"));
label_3.setBounds(398, 112, 46, 48);
contentPane.add(label_3);
JLabel label_4 = new JLabel("New label");
label_4.setIcon(new ImageIcon("C:\\Users\\achermen\\Desktop\\1303860240_list-remove.png"));
label_4.setBounds(447, 112, 46, 48);
contentPane.add(label_4);
}
}
这是画线的代码
public void paint(Graphics graphics)
{
graphics.drawLine(10, 20, 300, 310);
}
那么如何使用这条线......
提前致谢。
此致，
Ali
使用以下方法绘制线条可能会更容易：
这相关的example可能会提供一些额外的指导。
Action与键绑定的接口。import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
/**
* @see https://stackoverflow.com/questions/6991648
* @see https://stackoverflow.com/questions/6887296
* @see https://stackoverflow.com/questions/5797965
*/
public class LinePanel extends JPanel {
private MouseHandler mouseHandler = new MouseHandler();
private Point p1 = new Point(100, 100);
private Point p2 = new Point(540, 380);
private boolean drawing;
public LinePanel() {
this.setPreferredSize(new Dimension(640, 480));
this.addMouseListener(mouseHandler);
this.addMouseMotionListener(mouseHandler);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.blue);
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setStroke(new BasicStroke(8,
BasicStroke.CAP_ROUND, BasicStroke.JOIN_BEVEL));
g.drawLine(p1.x, p1.y, p2.x, p2.y);
}
private class MouseHandler extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
drawing = true;
p1 = e.getPoint();
p2 = p1;
repaint();
}
@Override
public void mouseReleased(MouseEvent e) {
drawing = false;
p2 = e.getPoint();
repaint();
}
@Override
public void mouseDragged(MouseEvent e) {
if (drawing) {
p2 = e.getPoint();
repaint();
}
}
}
private class ControlPanel extends JPanel {
private static final int DELTA = 10;
public ControlPanel() {
this.add(new MoveButton("\u2190", KeyEvent.VK_LEFT, -DELTA, 0));
this.add(new MoveButton("\u2191", KeyEvent.VK_UP, 0, -DELTA));
this.add(new MoveButton("\u2192", KeyEvent.VK_RIGHT, DELTA, 0));
this.add(new MoveButton("\u2193", KeyEvent.VK_DOWN, 0, DELTA));
}
private class MoveButton extends JButton {
KeyStroke k;
int dx, dy;
public MoveButton(String name, int code,
final int dx, final int dy) {
super(name);
this.k = KeyStroke.getKeyStroke(code, 0);
this.dx = dx;
this.dy = dy;
this.setAction(new AbstractAction(this.getText()) {
@Override
public void actionPerformed(ActionEvent e) {
LinePanel.this.p1.translate(dx, dy);
LinePanel.this.p2.translate(dx, dy);
LinePanel.this.repaint();
}
});
ControlPanel.this.getInputMap(WHEN_IN_FOCUSED_WINDOW)
.put(k, k.toString());
ControlPanel.this.getActionMap()
.put(k.toString(), new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
MoveButton.this.doClick();
}
});
}
}
}
private void display() {
JFrame f = new JFrame("LinePanel");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.add(new ControlPanel(), BorderLayout.SOUTH);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new LinePanel().display();
}
});
}
}