我想在两个 JPanel 之间画线，但线没有出现在 layeredPane 上。
这就是我所做的，请通过它，可编译。请尝试并更正此代码。我曾尝试以这种方式在内部框架上绘制线条，但它不适用于 JPanel。
package build;
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.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
public class LinkLayerPane1 {
public static void main(String[] args) {
new LinkLayerPane1();
}
public LinkLayerPane1() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
JLayeredPane layer = new JLayeredPane();
JPanel red = new JPanel();
red.setBackground(Color.RED);
JPanel blue = new JPanel();
blue.setBackground(Color.BLUE);
red.setBounds(50, 50, 50, 50);
blue.setBounds(125, 125, 50, 50);
layer.add(red);
layer.add(blue);
Point Red= new Point();
Red.x=red.getX()+(red.getWidth()/2);
Red.y=red.getY()-(red.getHeight()/2);
Point Blue= new Point();
Blue.x=blue.getX()+(blue.getWidth()/2);
Blue.y=blue.getY()-(blue.getHeight()/2);
handleDrag(red,Blue);
handleDrag(blue,Red);
layer.add(new LinkPane(red, blue), new Integer(JLayeredPane.DEFAULT_LAYER + 1));
layer.setPreferredSize(new Dimension(250, 250));
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(layer);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class LinkPane extends JPanel {
private Point startPoint;
private Point endPoint;
public LinkPane(JPanel panel1, JPanel panel2) {
setOpaque(false);
Point p1 = panel1.getLocation();
Point p2 = panel2.getLocation();
startPoint = new Point();
endPoint = new Point();
Point from = new Point();
Point to = new Point();
if (p1.x < p2.x) {
from.x = p1.x + (panel1.getWidth() / 2);
to.x = p2.x + (panel2.getWidth() / 2);
} else {
from.x = p2.x + (panel2.getWidth() / 2);
to.x = p1.x + (panel1.getWidth() / 2);
startPoint.x = p2.x;
}
if (p1.y < p2.y) {
from.y = p1.y + (panel1.getHeight()/ 2);
to.y = p2.y + (panel2.getHeight()/ 2);
} else {
from.y = p2.y + (panel2.getHeight()/ 2);
to.y = p1.y + (panel1.getHeight()/ 2);
}
int width = Math.max(1, to.x - from.x);
int height = Math.max(1, to.y - from.y);
setLocation(from);
setSize(width, height);
System.out.println(getBounds());
if (p1.x < p2.x) {
startPoint.x = 0;
endPoint.x = getWidth();
} else {
startPoint.x = getWidth();
endPoint.x = 0;
}
if (p1.y < p2.y) {
startPoint.y = 0;
endPoint.y = getHeight();
} else {
startPoint.y = getHeight();
endPoint.y = 0;
}
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setStroke(new BasicStroke(3, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
g2d.drawLine(startPoint.x, startPoint.y, endPoint.x, endPoint.y);
g2d.dispose();
}
}
//Dragging
public static void handleDrag(final JPanel Tpanel,final Point to)
{
final JPanel p = Tpanel;
Tpanel.addMouseMotionListener(new MouseMotionAdapter() {
@Override
public void mouseDragged(MouseEvent me) {
me.translatePoint(me.getComponent().getLocation().x, me.getComponent().getLocation().y);
//Handling Panel Dragging
p.setLocation(me.getX(), me.getY());
//Finding new point
Point p1 = Tpanel.getLocation();
Point p2=to;
Point startPoint = new Point();
Point endPoint = new Point();
Point from = new Point();
if (p1.x < p2.x) {
from.x = p1.x + (Tpanel.getWidth() / 2);
to.x = p2.x + (Tpanel.getWidth() / 2);
} else {
from.x = p2.x + (Tpanel.getWidth() / 2);
to.x = p1.x + (Tpanel.getWidth() / 2);
startPoint.x = p2.x;
}
if (p1.y < p2.y) {
from.y = p1.y + (Tpanel.getHeight()/ 2);
to.y = p2.y + (Tpanel.getHeight()/ 2);
} else {
from.y = p2.y + (Tpanel.getHeight()/ 2);
to.y = p1.y + (Tpanel.getHeight()/ 2);
}
int width = Math.max(1, to.x - from.x);
int height = Math.max(1, to.y - from.y);
if (p1.x < p2.x) {
startPoint.x = 0;
endPoint.x = Tpanel.getWidth();
} else {
startPoint.x = Tpanel.getWidth();
endPoint.x = 0;
}
if (p1.y < p2.y) {
startPoint.y = 0;
endPoint.y = Tpanel.getHeight();
} else {
startPoint.y = Tpanel.getHeight();
endPoint.y = 0;
}
}
});
}
}
