JFrame class
It is the object of the window on the screen, which can be maximized, minimized, and closed to solve the three basic building blocks of Swing
Organize (buttons, labels, text fields) and present them to the user-(container)
JPanel class
It is the panel container class in the java graphical user interface (GUI) toolkit swing. It is a lightweight container that can be added to the Fram form. It can be nested and combined, and contains other components (Buttons) in different sub-containers. , TextArea, etc.) The function is to combine these controls on the form.
The following is part of the code implementation:
package mini.draw.Pad;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
/**
* 画图工具类
* 1.创建一个窗体
* 2.创建面图花板
* 3.实现随笔画功能
* 4.扩充菜单栏
* 5.扩充性状态栏（按钮）
*/
public class MiniDrawPad {
private JFrame jFrame = new JFrame("迷你画图板");//带有标题和边框的顶层窗口
//定义画图区域的高度和宽度
private final int WIDTH = 1000;
private final int HEIGHT = 700;
private MyPanel mp = new MyPanel();
//定义一个BufferedImage对象,并获取image对象的Graphics-画笔
BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
//指定一个宽和高，创建一个不带透明色的对象
Graphics2D g = (Graphics2D) image.getGraphics(); //获得在图像上画图的工具-画笔
//设置画笔的颜色
private Color color = Color.black; //当前默认颜色黑色
//画笔的粗细
private float stroke = 1.0f;
//上一次鼠标拖动事件的鼠标坐标
private int prex = -1;
private int prey = -1;
int R, G, B; //用来存放当前的色彩值
String style1; //用来存放当前字体
JLabel statusBar;//当前鼠标状态
//创建画板类
public class MyPanel extends JPanel {
//设置画板
public MyPanel() {
setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
setBounds(0, 0, WIDTH, HEIGHT);
setBackground(Color.WHITE);
}
public void paint(Graphics g) {
g.drawImage(image, 0, 0, null);
//img-要绘制的指定图像，如果为null，该方法不执行任何操作
}
}
//选择颜色
public void chooseColor() {
color = JColorChooser.showDialog(jFrame, "选择颜色", color);
R = color.getRed();
G = color.getGreen();
B = color.getBlue();
color = new Color(R, G, B);
}
//获取画笔
//创建菜单条
public void createBar() {
JMenuBar bar = new JMenuBar();//定义菜单条
JMenu fileMenu = new JMenu("file");//
fileMenu.setMnemonic('F');//表示助记符的键代码
JMenuItem newItem = new JMenuItem("New");//菜单项
newItem.setMnemonic('N');
JMenuItem saveItem = new JMenuItem("Save");//菜单项
saveItem.setMnemonic('S');
JMenuItem openItem = new JMenuItem("Open");//菜单项
openItem.setMnemonic('O');
//退出菜单项
JMenuItem exitItem = new JMenuItem("Exit");//菜单项
exitItem.setMnemonic('E');
exitItem.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
fileMenu.add(newItem);
fileMenu.add(saveItem);
fileMenu.add(openItem);
fileMenu.addSeparator();
fileMenu.add(exitItem);
//颜色菜单
JMenu colorMenu = new JMenu("Color");
JMenuItem colorItem = new JMenuItem("Choose Color");
colorItem.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
//如果被触发，则调用选择颜色函数段
chooseColor();
}
});
colorMenu.add(colorItem);
//设置线条粗细菜单
JMenu strokeMenu = new JMenu("Stroke");
JMenuItem strokeItem = new JMenuItem("Set Stroke");
strokeItem.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
//如果被触发，则调用设置线条粗细的函数段
setStroke();
}
});
strokeMenu.add(strokeItem);
//设置提示菜单
JMenu helpMenu = new JMenu("Help");
JMenuItem aboutItem = new JMenuItem("About this Draw pad!");
aboutItem.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(null, "this is a mini draw pad Copy(c)2020",
"画图板程序说明", JOptionPane.INFORMATION_MESSAGE);
}
});
helpMenu.add(aboutItem);
bar.add(fileMenu);
bar.add(colorMenu);
bar.add(strokeMenu);
bar.add(helpMenu);
jFrame.setJMenuBar(bar);
}
//设置线条粗细
public void setStroke() {
String input = JOptionPane.showInputDialog("请输入一个float数值( >0 )");
stroke = Float.parseFloat(input);
}
//创建按钮
public void createButton() {
JToolBar buttonPanel = new JToolBar(JToolBar.HORIZONTAL);
String[] buttonNames = {"随笔", "直线", "空心圆", "空心矩形", "橡皮擦", "文字按钮"};
for (int i = 0; i < buttonNames.length; i++) {
JButton button = new JButton(buttonNames[i]);
buttonPanel.add(button);
}
//设置字体风格的选择
String[] styleNames = {"宋体", "隶书", "楷体", "仿宋", "华文行楷", "方正舒体", "仿宋_GB2312", "Serif"};
JComboBox styles = new JComboBox<>(styleNames);
styles.setMaximumRowCount(6); //设置JComboBox显示的最大行数
styles.addItemListener(new ItemListener() {
@Override
public void itemStateChanged(ItemEvent e) {
style1 = styleNames[styles.getSelectedIndex()];
}
});
styles.setMinimumSize(new Dimension(50, 20));
styles.setMaximumSize(new Dimension(120, 20));
JCheckBox bold = new JCheckBox("BOLD"); //复选框
JCheckBox italic = new JCheckBox("ITALIC"); //
buttonPanel.add(bold);
buttonPanel.add(italic);
buttonPanel.add(styles);
statusBar = new JLabel("当前的鼠标状态");
statusBar.setText("welcome minidraw pad!!!");
Container c = jFrame.getContentPane();//初始化一个容器
c.add(buttonPanel, BorderLayout.NORTH);
c.add(statusBar, BorderLayout.SOUTH);
}
public void init() {
/**
对于鼠标的移动和拖放，用鼠标运动监听器MouseMotionListener
*/
mp.addMouseMotionListener(new MouseMotionAdapter() {
@Override
public void mouseDragged(MouseEvent e) {
if (prex > 0 && prey > 0) {
g.setColor(color);
g.setStroke(new BasicStroke(stroke, BasicStroke.CAP_ROUND, BasicStroke.JOIN_BEVEL));
g.drawLine(prex, prey, e.getX(), e.getY());
//x1,x2是确定直线的起始点，分别是横纵坐标，同理x2,y2确定直线的终点
}
prex = e.getX();
prey = e.getY();
statusBar.setText("Mouse Press @[" + e.getX() + "," + e.getY() + "]");
mp.repaint(); //重绘mp对象
}
});
jFrame.setBounds(0, 0, WIDTH, HEIGHT);
jFrame.addWindowListener(new WindowAdapter() {
@Override
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
g.fillRect(0, 0, WIDTH, HEIGHT);
jFrame.add(mp);
createBar();
createButton();
jFrame.setVisible(true);
}
public static void main(String[] args) {
MiniDrawPad miniDrawPad = new MiniDrawPad();
miniDrawPad.init();
}
}
Due to time constraints, I couldn't finish it, only half of it. . . I will continue to finish when I have time.