Java 喷漆组件未在JPanel上喷漆
我正在做一个家庭作业,我应该做一个程序,让你画自定义的形状和线条,并在屏幕上移动它们 最初,我使用public voidJava 喷漆组件未在JPanel上喷漆,java,swing,jpanel,awt,paintcomponent,Java,Swing,Jpanel,Awt,Paintcomponent,我正在做一个家庭作业,我应该做一个程序,让你画自定义的形状和线条,并在屏幕上移动它们 最初,我使用public voidpaint(g)进行绘制,但当我调用repaint时,图形会闪烁 因此,我切换到paintComponent(g)。然而,当我试图画一个形状时,什么也看不出来。我相信这是因为它不是在JPanel之上绘制的 框架在3行BorderLayout中有3个面板 [Button JPanel] [Draw Box JPanel] [Coordinate Jpanel] 我想画的面板自然
paint(g)
进行绘制,但当我调用repaint时,图形会闪烁
因此,我切换到paintComponent(g)
。然而,当我试图画一个形状时,什么也看不出来。我相信这是因为它不是在JPanel
之上绘制的
框架在3行BorderLayout
中有3个面板
[Button JPanel]
[Draw Box JPanel]
[Coordinate Jpanel]
我想画的面板自然是画框面板
以下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();
}
}
您的Main类扩展了JPanel,有一个paintComponent方法,但是您从未将Main的实例添加到GUI中,而是将普通的JPanel、drawBox添加到GUI中,因此当然不会调用paintComponent
解决方案:将Main或
这个添加到GUI中,而不是一个普通的JPanel。您的主类扩展了JPanel,有一个paintComponent方法——但是您从不将Main的实例添加到GUI中,而是将普通的JPanel、drawBox添加到GUI中,因此当然永远不会调用paintComponent
解决方案:将Main或此
添加到GUI,而不是普通的JPanel
我想画的面板是draw Box JPanel
您没有覆盖“drawBox”面板的paintComponent(…)
方法,因此不会进行绘制
另外,每当您总是需要在paintComponent(…)方法的开始处调用super.paintComponent(…)时
查看定制绘画的两种常用方法的工作示例
我想画的面板是draw Box JPanel
您没有覆盖“drawBox”面板的paintComponent(…)
方法,因此不会进行绘制
另外,每当您总是需要在paintComponent(…)方法的开始处调用super.paintComponent(…)时
查看定制绘画的两种常用方法的工作示例。谢谢,这似乎很有效。我把drawBox JPanel都扔掉了,取而代之的是在相框上加上了“这个”。谢谢你,这似乎很管用。我把drawBox JPanel都扔掉了,取而代之的是在相框上加上了“this”。
drawBox = new JPanel();