java， 在 JScrollPane 中添加 JlayeredPane 仅显示空白背景

Question

我已经为此寻找解决方案，但它们不起作用。也许是因为我的设置不同。我正在尝试制作一个电梯模拟器，我有这个图： 图 我有这个代码：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
@SuppressWarnings("serial")
public class Test extends JFrame {
public Test() {
Container contentPane = getContentPane();
GridBagConstraints constraints = new GridBagConstraints();
JButton floor = new JButton();
JLabel cab = new JLabel();
JPanel floorPanel = new JPanel();
JPanel cabPanel = new JPanel();
JLayeredPane layeredPane = new JLayeredPane();
JScrollPane scroll = new JScrollPane();
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
contentPane.setBackground(Color.BLUE);
contentPane.setLayout(new GridBagLayout());
constraints.insets = new Insets(20, 92, 20, 92);
floorPanel.setLayout(new FlowLayout(FlowLayout.LEFT, 0, 0));
floorPanel.setPreferredSize(new Dimension(165, 165));
floor.setPreferredSize(new Dimension(165, 165));
floor.setBackground(Color.WHITE);
floor.setText("1");
cab.setPreferredSize(new Dimension(165, 165));
cab.setText("Cab");
cab.setBackground(Color.BLACK);
cab.setLocation(0, 0);
cabPanel.setLayout(null);
cabPanel.setPreferredSize(new Dimension(165, 165));
cabPanel.setOpaque(false);
cabPanel.add(cab);
layeredPane.setLayout(new BorderLayout());
layeredPane.setPreferredSize(new Dimension(165, 165));
layeredPane.add(floorPanel, 0);
layeredPane.add(cabPanel, 1);
scroll.setMinimumSize(new Dimension(183, 660));
scroll.setMaximumSize(new Dimension(183, 660));
scroll.setViewportView(layeredPane);
contentPane.add(scroll, constraints);
pack();
setVisible(true);
}
}

它不会显示添加到 JLayeredPane 的两个 JPael，只显示空白背景。我在JLayeredPane的第二层的JPanel上尝试了setOpaque(false(，但它仍然不起作用。

如果您碰巧已经在某处找到了解决方案，请发送链接。 对不起，语法错误

Answer 1

同样，对于 JLayeredPane，您需要设置添加到 JLayeredPane 的任何组件的位置和位置，因为它的行为就像它具有空布局，但带有图层。

例如，签出并运行以下代码：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;
import javax.swing.border.Border;
@SuppressWarnings("serial")
public class LayeredExample extends JPanel {
public LayeredExample() {
int gridRows = 20;
int gridCols = 10;
JPanel panelA = new JPanel(new GridLayout(gridRows, gridCols));
for (int i = 0; i < gridRows; i++) {
for (int j = 0; j < gridCols; j++) {
String labelText = String.format("[%d, %d]", j + 1, i + 1);
JLabel label = new JLabel(labelText);
Border outsideBorder = BorderFactory.createLineBorder(Color.BLUE);
Border insideBorder = BorderFactory.createEmptyBorder(3, 3, 3, 3);
label.setBorder(BorderFactory.createCompoundBorder(outsideBorder, insideBorder));
panelA.add(label);
}
}
panelA.setBorder(BorderFactory.createTitledBorder("Panel A"));
panelA.setSize(panelA.getPreferredSize());
panelA.setLocation(0, 0);
JLabel dragMeLabel = new JLabel("Drag Me!");
dragMeLabel.setFont(dragMeLabel.getFont().deriveFont(Font.BOLD, 54f));
JPanel panelB = new JPanel(new GridBagLayout());
panelB.add(dragMeLabel);
panelB.setBorder(BorderFactory.createTitledBorder("Panel B"));
panelB.setPreferredSize(new Dimension(800, 500));
panelB.setSize(panelB.getPreferredSize());
panelB.setLocation(200, 200);
MouseAdapter myMouse = new MouseAdapter() {
private Point p0;
private Point loc0;
@Override
public void mousePressed(MouseEvent e) {
p0 = e.getLocationOnScreen();
loc0 = ((JComponent) e.getSource()).getLocation();
}
private void moveComponent(MouseEvent e) {
if (p0 == null || loc0 == null) {
return;
}
Point p1 = e.getLocationOnScreen();
JComponent comp = (JComponent)e.getSource();
Container cont = comp.getParent();
int x = loc0.x + p1.x - p0.x;
int y = loc0.y + p1.y - p0.y;
Point loc1 = new Point(x, y);
comp.setLocation(loc1);
cont.repaint();
}
@Override
public void mouseDragged(MouseEvent e) {
moveComponent(e);
}
@Override
public void mouseReleased(MouseEvent e) {
moveComponent(e);
p0 = null;
loc0 = null;
}
};
panelB.addMouseListener(myMouse);
panelB.addMouseMotionListener(myMouse);
JLayeredPane layeredPane = new JLayeredPane();
layeredPane.add(panelA, JLayeredPane.DEFAULT_LAYER);
layeredPane.add(panelB, JLayeredPane.PALETTE_LAYER);
layeredPane.setPreferredSize(new Dimension(1600, 1200));
JScrollPane scrollPane = new JScrollPane(layeredPane);
scrollPane.getViewport().setPreferredSize(new Dimension(800, 650));
setLayout(new BorderLayout());
add(scrollPane);
}
private static void createAndShowGui() {
JFrame frame = new JFrame("LayeredExample");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new LayeredExample());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}