我正在做一项家庭作业，我应该制作一个程序，允许您绘制自定义形状和线条，并将它们在屏幕上移动。
最初我使用的是 public voidpaint(g)绘制，但当我调用重新绘制时，形状在闪烁。
因此我切换到paintComponent(g)。然而，当我尝试绘制形状时，什么也没有显示。我相信这是因为它没有画在上面JPanel.
该框架有 3 个面板，排成 3 行BorderLayout.
[Button JPanel]
[Draw Box JPanel]
[Coordinate Jpanel]
我想在其上绘图的面板自然是“绘图盒”面板。
这是我目前拥有的代码：
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
public class Main extends JPanel implements ActionListener, MouseListener, MouseMotionListener {
private String colors[] = { "Black", "Red", "Orange", "Yellow", "Green", "Blue" };
private String shapes[] = { "Ellipse", "Line", "Rectangle" };
private JMenuBar toolBar; // flow layout? OR box layout x-Axis
private JPanel drawBox;
private JPanel coordBox;
private JLabel coords;
private JButton undo = new JButton("Undo");
private JButton clear = new JButton("Clear");
private JComboBox color = new JComboBox(colors);
private JComboBox shape = new JComboBox(shapes);
private JCheckBox fill = new JCheckBox("Filled");
public Main() {
JFrame frame = new JFrame("Paint");
frame.setSize(400, 600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setLayout(new BorderLayout());
/*
* SETUP TOOLBAR
*/
toolBar = new JMenuBar();
toolBar.setLayout(new GridLayout(1, 5));
toolBar.add(undo);
toolBar.add(clear);
toolBar.add(color);
toolBar.add(shape);
toolBar.add(fill);
/*
* ADD ACTION LISTENERS TO BUTTONS
*/
undo.addActionListener(this);
clear.addActionListener(this);
color.addActionListener(this);
shape.addActionListener(this);
fill.addActionListener(this);
/*
* SETUP DRAW BOX
*/
drawBox = new JPanel();
drawBox.setOpaque(true);
drawBox.setPreferredSize(new Dimension(600, 400));
drawBox.addMouseListener(this);
drawBox.addMouseMotionListener(this);
/*
* SETUP COORDINATES
*/
coords = new JLabel();
coordBox = new JPanel();
coordBox.setBackground(new Color(211, 211, 211));
coordBox.setPreferredSize(new Dimension(drawBox.getWidth(), 25));
coords.setText("Coords: [0,0]");
coords.addMouseMotionListener(this);
coordBox.add(coords);
/*
* ADD TO FRAME
*/
frame.add(toolBar, BorderLayout.NORTH);
frame.add(drawBox, BorderLayout.CENTER);
frame.add(coordBox, BorderLayout.SOUTH);
frame.pack();
}
public static void main(String[] args) {
Main m = new Main();
}
public void paintComponent(Graphics g) {
// super.paintComponent(g);
g.setColor(Color.BLACK);
g.fillRect(300, 300, 100, 100);
}
@Override
public void actionPerformed(ActionEvent e) {
if (e.getSource() == undo) {
System.out.println("Undo Last");
}
if (e.getSource() == clear) {
System.out.println("clearing screen");
}
// COLOR DROP DOWN BOX
if (e.getSource() == color) {
JComboBox cb = (JComboBox) e.getSource();
String selected = (String) cb.getSelectedItem();
switch (selected) {
case "Red":
System.out.println("switching to color red");
//ellipse.setColor(Color.RED);
break;
case "Orange":
System.out.println("switch to coor orange");
//ellipse.setColor(Color.ORANGE);
break;
case "Yellow":
System.out.println("switching to color yellow");
break;
case "Green":
System.out.println("Switching to green");
//ellipse.setColor(Color.GREEN);
break;
case "Blue":
System.out.println("Switching to blue");
break;
default:
System.out.println("NOthing selected");
break;
}
}
// SHAPE DROP DOWN BOX
if (e.getSource() == shape) {
JComboBox cb = (JComboBox) e.getSource();
String selected = (String) cb.getSelectedItem();
switch (selected) {
case "Ellipse":
System.out.println("switching to ellipse");
break;
case "Line":
System.out.println("switch to line");
break;
case "Rectangle":
System.out.println("switching to rectangle");
break;
default:
System.out.println("NOthing selected");
break;
}
}
if (e.getSource() == fill) {
JCheckBox cb = (JCheckBox) e.getSource();
if (cb.isSelected()) {
System.out.println("Fill shape");
//ellipse.setFilled(true);
} else {
System.out.println("Empty shape");
//ellipse.setFilled(false);
}
}
}
@Override
public void mouseClicked(MouseEvent arg0) {
// System.out.println("Mouse clicked");
}
@Override
public void mouseEntered(MouseEvent e) {
System.out.println("Mouse entered");
}
@Override
public void mouseExited(MouseEvent arg0) {
coords.setText("Coords: N/A");
}
@Override
public void mousePressed(MouseEvent arg0) {
System.out.println("Mouse pressed");
}
@Override
public void mouseReleased(MouseEvent arg0) {
System.out.println("Mouse Released");
}
@Override
public void mouseDragged(MouseEvent e) {
coords.setText("Coords: [" + e.getX() + "," + e.getY() + "]");
}
@Override
public void mouseMoved(MouseEvent e) {
coords.setText("Coords: [" + e.getX() + "," + e.getY() + "]");
// repaint();
// revalidate();
}
}
