public enum ShapeTypes {
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LINE, CIRCLE, RECTANGLE
}
public interface Shape {
void paint(Graphics g);
}
public class Rectangle implements Shape {
// 矩形左上角的坐标
private int x, y;
// 矩形的宽度和高度
private int width, height;
private Color rectangleColor;
public Rectangle() {
super();
}
public Rectangle(int x, int y, int width, int height, Color rectangleColor) {
super();
this.x = x;
this.y = y;
this.width = width;
this.height = height;
this.rectangleColor = rectangleColor;
}
@Override
public void paint(Graphics g) {
g.setColor(rectangleColor);
g.drawRect(x, y, width, height);
}
}
public class Line implements Shape {
// 直线的起始位置
private int x1, y1;
// 直线的终止位置
private int x2, y2;
private Color lineColor;
public Line(int x1, int y1, int x2, int y2, Color lineColor) {
super();
this.x1 = x1;
this.y1 = y1;
this.x2 = x2;
this.y2 = y2;
this.lineColor = lineColor;
}
public Line() {
super();
}
@Override
public void paint(Graphics g) {
g.setColor(lineColor);
g.drawLine(x1, y1, x2, y2);
}
}
public class Circle implements Shape {
// 圆的颜色
private Color circleColor;
// 圆心的坐标
private int x, y;
// 圆的半径
private int radius;
public Circle() {
super();
}
public Circle(int x, int y, int radius, Color circleColor) {
super();
this.circleColor = circleColor;
this.x = x;
this.y = y;
this.radius = radius;
}
@Override
public void paint(Graphics g) {
g.setColor(circleColor);
// 画弧, 当弧的宽度和高度一致且从0~360度时就是原形了
g.drawArc(x, y, radius, radius, 0, 360);
}
}
public class SketchpadPanel extends Canvas implements MouseListener, MouseMotionListener {
private static final long serialVersionUID = -5229161042153132522L;
// 鼠标点击起始坐标和当前坐标
private int beginX = 0, beginY = 0, currentX = 0, currentY = 0;
// 判断鼠标是否被按下
private boolean isMousePressing = false;
// 保存当前的图形, 在撤销和恢复时使用
private final StackShape currentShapes = new StackShape();
// 保存已经删除过的图形
private final StackShape deletedShapes = new StackShape();
private ShapeTypes type;
private Color color;
public SketchpadPanel() {
addMouseListener(this);
addMouseMotionListener(this);
}
/**
* 撤销方法
*/
public void undo() {
if (currentShapes.size() 0) {
// 从所有保存过的图形中取出最后一个, 放入到已删除的图形中去
Shape shape = currentShapes.pop();
deletedShapes.push(shape);
repaint();
}
}
/**
* 恢复撤销方法
*/
public void redo() {
if (deletedShapes.size() 0) {
// 从所有删除的图形中取出最后一个, 放入保存的图形中
Shape shape = deletedShapes.pop();
currentShapes.push(shape);
repaint();
}
}
/**
* 设置命令
*
* @param type
*/
public void setShapeType(ShapeTypes type) {
this.type = type;
}
/**
* 设置颜色
*
* @param color
*/
public void setColor(Color color) {
this.color = color;
}
public void updete(Graphics g) {
paint(g);
}
/**
* 绘制画板
*/
@Override
public void paint(Graphics g) {
// 绘制画板
Dimension size = getSize();
int width = size.width;
int height = size.height;
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
// 绘制所有图形
Shape shape = null;
EnumerationShape e = currentShapes.elements();
while (e.hasMoreElements()) {
shape = e.nextElement();
shape.paint(g);
}
// 如果当前鼠标没有释放
if (isMousePressing) {
g.setColor(color);
switch (type) {
// 绘制直线
case LINE:
g.drawLine(beginX, beginY, currentX, currentY);
break;
// 绘制矩形
case RECTANGLE:
if (currentX beginX) {
if (currentY beginY) {
// 如果当前位置在起始位置的左上方, 则以鼠标当前位置为矩形的左上角位置
g.drawRect(currentX, currentY, beginX - currentX, beginY - currentY);
} else {
// 如果当前位置在起始位置的左下方, 则以鼠标当前位置的横坐标和起始位置的纵坐标作为矩形的左上角位置
g.drawRect(currentX, beginY, beginX - currentX, currentY - beginY);
}
} else {
if (currentY beginY) {
// 如果当前位置在起始位置的右上方, 则以鼠标起始位置的很坐标和当前位置的纵坐标作为矩形的左上角位置
g.drawRect(beginX, currentY, currentX - beginX, beginY - currentY);
} else {
// 如果当前位置在起始位置的右下方, 则已起始位置作为矩形的左上叫位置
g.drawRect(beginX, beginY, currentX - beginX, currentY - beginY);
}
}
break;
// 绘制圆形
case CIRCLE:
// 半径为a*a + b*b的平方根
int radius = (int) Math
.sqrt((beginX - currentX) * (beginX - currentX) + (beginY - currentY) * (beginY - currentY));
g.drawArc(beginX - radius / 2, beginY - radius / 2, radius, radius, 0, 360);
break;
}
}
}
@Override
public void mouseClicked(MouseEvent e) {
}
@Override
public void mouseEntered(MouseEvent e) {
}
@Override
public void mouseExited(MouseEvent e) {
}
/**
* 当鼠标按下的时候获得起始坐标
*/
@Override
public void mousePressed(MouseEvent e) {
beginX = e.getX();
beginY = e.getY();
isMousePressing = true;
}
/**
* 当鼠标释放时获得当前坐标
*/
@Override
public void mouseReleased(MouseEvent e) {
currentX = e.getX();
currentY = e.getY();
isMousePressing = false;
// 当释放鼠标时, 将绘制的图形保存到shapes中
switch (type) {
// 绘制直线
case LINE:
Line line = new Line(beginX, beginY, currentX, currentY, color);
currentShapes.push(line);
break;
// 绘制圆形
case CIRCLE:
// 半径为a*a + b*b的平方根
int radius = (int) Math
.sqrt((beginX - currentX) * (beginX - currentX) + (beginY - currentY) * (beginY - currentY));
Circle circle = new Circle(beginX - radius / 2, beginY - radius / 2, radius, color);
currentShapes.push(circle);
break;
// 绘制矩形
case RECTANGLE:
Rectangle rectangle = null;
if (currentX beginX) {
if (currentY beginY) {
rectangle = new Rectangle(currentX, currentY, beginX - currentX, beginY - currentY, color);
} else {
rectangle = new Rectangle(currentX, beginY, beginX - currentX, currentY - beginY, color);
}
} else {
if (currentY beginY) {
rectangle = new Rectangle(beginX, currentY, currentX - beginX, beginY - currentY, color);
} else {
rectangle = new Rectangle(beginX, beginY, currentX - beginX, currentY - beginY, color);
}
}
currentShapes.push(rectangle);
break;
}
repaint();
}
@Override
public void mouseDragged(MouseEvent e) {
currentX = e.getX();
currentY = e.getY();
this.repaint();
}
@Override
public void mouseMoved(MouseEvent e) {
}
}
public class SketchpadFrame extends JFrame {
private static final long serialVersionUID = -7080053971741609904L;
private final JPanel commandPanel = new JPanel(); // 存放命令的面板
private final JPanel colorPanel = new JPanel(); // 存放颜色的面板
private final JPanel mainPanel = new JPanel(); // 主面板
private final JButton redButton = new JButton("红色");
private final JButton blueButton = new JButton("蓝色");
private final JButton greenButton = new JButton("绿色");
private final JButton lineButton = new JButton("直线");
private final JButton circleButton = new JButton("圆");
private final JButton rectangleButton = new JButton("矩形");
private final JButton undoButton = new JButton("撤销");
private final JButton redoButton = new JButton("恢复撤销");
private final JButton exitButton = new JButton("退出");
SketchpadPanel sketchPanel = new SketchpadPanel();
private void initFrame() {
commandPanel.setLayout(new FlowLayout());
commandPanel.add(lineButton);
commandPanel.add(circleButton);
commandPanel.add(rectangleButton);
commandPanel.add(undoButton);
commandPanel.add(redoButton);
commandPanel.add(exitButton);
colorPanel.setLayout(new FlowLayout());
colorPanel.add(redButton);
colorPanel.add(blueButton);
colorPanel.add(greenButton);
mainPanel.setLayout(new BorderLayout());
mainPanel.add(commandPanel, BorderLayout.NORTH);
mainPanel.add(colorPanel, BorderLayout.CENTER);
getContentPane().add("South", mainPanel);
getContentPane().add("Center", sketchPanel);
// 初始化设置:颜色和命令
lineButton.setForeground(Color.RED);
sketchPanel.setColor(Color.RED);
redButton.setForeground(Color.RED);
sketchPanel.setShapeType(ShapeTypes.LINE);
}
private void initListener() {
redButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
redAction(e);
}
});
blueButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
blueAction(e);
}
});
greenButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
greenAction(e);
}
});
undoButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
undoAction(e);
}
});
redoButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
redoAction(e);
}
});
exitButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
exitAction(e);
}
});
lineButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
lineAction(e);
}
});
circleButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
circleAction(e);
}
});
rectangleButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
rectangleAction(e);
}
});
}
public SketchpadFrame() {
initFrame();
initListener();
this.setSize(500, 600);
setLocationByPlatform(true);
setResizable(true);
}
/* ********************处理事件********************* */
private void undoAction(ActionEvent e) {
sketchPanel.undo();
}
private void redoAction(ActionEvent e) {
sketchPanel.redo();
}
private void exitAction(ActionEvent e) {
System.exit(0);
}
private void lineAction(ActionEvent e) {
// 选中按钮为红色, 其余为黑色
lineButton.setForeground(Color.RED);
circleButton.setForeground(Color.BLACK);
rectangleButton.setForeground(Color.BLACK);
sketchPanel.setShapeType(ShapeTypes.LINE);
}
private void circleAction(ActionEvent e) {
circleButton.setForeground(Color.RED);
lineButton.setForeground(Color.BLACK);
rectangleButton.setForeground(Color.BLACK);
sketchPanel.setShapeType(ShapeTypes.CIRCLE);
}
private void rectangleAction(ActionEvent e) {
rectangleButton.setForeground(Color.RED);
lineButton.setForeground(Color.BLACK);
circleButton.setForeground(Color.BLACK);
sketchPanel.setShapeType(ShapeTypes.RECTANGLE);
}
private void redAction(ActionEvent e) {
redButton.setForeground(Color.RED);
blueButton.setForeground(Color.BLACK);
greenButton.setForeground(Color.BLACK);
sketchPanel.setColor(Color.RED);
}
private void blueAction(ActionEvent e) {
blueButton.setForeground(Color.RED);
redButton.setForeground(Color.BLACK);
greenButton.setForeground(Color.BLACK);
sketchPanel.setColor(Color.BLUE);
}
private void greenAction(ActionEvent e) {
greenButton.setForeground(Color.RED);
redButton.setForeground(Color.BLACK);
blueButton.setForeground(Color.BLACK);
sketchPanel.setColor(Color.GREEN);
}
}
/**
*
* @author 不落的太阳(Sean Yang)
* @version 1.0
* @since JDK 1.8
*
*/
public class SketchpadMain {
/**
* 测试方法
*
* @param args命令行参数
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new SketchpadFrame();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
});
}
}
package test.xxl;
import java.awt.Button;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
public class Demo0617 extends JFrame implements MouseListener,ActionListener{
private static int x = 0 ;
private static int y = 0 ;
private static int w = 0 ;
private static int h = 0 ;
private static Color c ;
// 真为圆，假为方
private boolean flag = false ;
private static final long serialVersionUID = 1L;
public Demo0617(){
this.setSize(440, 500) ;
this.setVisible(true) ;
this.setLayout(null) ;
this.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR)) ;
this.setResizable(false);//不能改变窗体大小
this.setBackground(Color.WHITE) ;
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) ;
this.addMouseListener(this) ;
this.getContentPane().setBackground(Color.WHITE) ;
Button b1,b2,b3,b4,b5,b6,b7,b8,b9 ;
b1 = new Button("红色") ;
b1.setBounds(0, 0, 100, 30) ;
b1.setBackground(Color.RED) ;
b1.addActionListener(this) ;
this.add(b1) ;
b2 = new Button("黑色") ;
b2.setBounds(110, 0, 100, 30) ;
b2.setBackground(Color.BLACK) ;
b2.addActionListener(this) ;
this.add(b2) ;
b3 = new Button("黄色") ;
b3.setBounds(220, 0, 100, 30) ;
b3.setBackground(Color.YELLOW) ;
b3.addActionListener(this) ;
this.add(b3) ;
b4 = new Button("蓝色") ;
b4.setBackground(Color.BLUE) ;
b4.setBounds(330, 0, 100, 30) ;
b4.addActionListener(this) ;
this.add(b4) ;
b5 = new Button("橡皮擦") ;
b5.setBounds(0, 40, 100, 30) ;
b5.addActionListener(this) ;
this.add(b5) ;
b6 = new Button("撤销") ;
b6.setBounds(110, 40, 100, 30) ;
b6.addActionListener(this) ;
this.add(b6) ;
b7 = new Button("全部删除") ;
b7.setBounds(220, 40, 100, 30) ;
b7.addActionListener(this) ;
this.add(b7) ;
b8 = new Button("圆形") ;
b8.setBounds(0, 80, 100, 30) ;
b8.addActionListener(this) ;
this.add(b8) ;
b9 = new Button("矩形") ;
b9.setBounds(110, 80, 100, 30) ;
b9.addActionListener(this) ;
this.add(b9) ;
}
/**
* @param args
*/
public static void main(String[] args) {
new Demo0617() ;
}
@Override
public void paint(Graphics g) {
if(c == null)
c = g.getColor();
g.setColor(c);
if(flag){
g.fillOval(x, y, w, h);
} else {
g.fillRect(x, y, w, h) ;
}
}
public void clear(Graphics g){
g.setColor(Color.WHITE) ;
g.clearRect(0, 0, 440, 500) ;
}
/**
* 单击
*/
@Override
public void mouseClicked(MouseEvent e) {
}
/**
* 按下
*/
@Override
public void mousePressed(MouseEvent e) {
x = e.getX() ;
y = e.getY() ;
}
/**
* 松开
*/
@Override
public void mouseReleased(MouseEvent e) {
int x = e.getX() ;
int y = e.getY() ;
if(x this.x){
w = x - this.x ;
} else {
w = this.x - x ;
}
if(y this.y){
h = y - this.y ;
} else {
h = this.y - y ;
}
paint(getGraphics()) ;
}
/**
* 鼠标进入事件
*/
@Override
public void mouseEntered(MouseEvent e) {
}
/**
* 鼠标移除事件
*/
@Override
public void mouseExited(MouseEvent e) {
}
@Override
public void actionPerformed(ActionEvent e) {
switch (e.getActionCommand().hashCode()) {
case 1038352:
// 红色
c = Color.RED ;
break;
case 1293761:
// 黑色
c = Color.BLACK ;
break;
case 1293358:
// 黄色
c = Color.YELLOW ;
break;
case 1087797:
// 蓝色
c = Color.BLUE ;
break;
case 27138585:
// 橡皮擦
c = Color.WHITE ;
break ;
case 836828:
Graphics graphics = getGraphics() ;
graphics.setColor(Color.WHITE) ;
if(flag){
graphics.fillOval(x, y, w, h) ;
} else {
graphics.fillRect(x, y, w, h) ;
}
break;
case 657183940:
// 全部删除
clear(getGraphics()) ;
break;
case 715036:
// 圆形
flag = true ;
break;
case 976025:
// 矩形
flag = false ;
break;
default:
System.out.println(e.getActionCommand().hashCode());
break ;
}
}
}
使用java画圆要用到绘图类Graphics，下面是实例代码和运行效果：
package com.dikea.demo01;
import java.awt.*;
import javax.swing.*;
// java绘图原理
public class demo_01 extends JFrame {
MyPanel mp = null;
public static void main(String[] args) {
// TODO 自动生成的方法存根
demo_01 demo01 = new demo_01();
}
public demo_01(){
mp = new MyPanel();
this.add(mp);
this.setSize(400, 300);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);
}
}
// 定义一个MyPanel面板，用于绘图区域
class MyPanel extends JPanel{
//覆盖JPanel
// Graphics 是绘图的重要类，可以理解成一支画笔
public void paint(Graphics g){
// 1. 调用父类函数完成初始化任务
// 这句话不可以少
super.paint(g);
// 先画出一个圆圈
g.drawOval(100, 100, 30, 30);
}
}
代码复制进ide编程工具，运行效果如下：
兄弟帮你写了一个：
import java.awt.Button;
import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Random;
public class Print {
public static void main(String[] args) {
new Te();
}
}
class Te extends Frame implements ActionListener {
Color cc = Color.red;
int x = -20, y = -50;
Random r = new Random();
public Te() {
this.setLayout(null);
Button b = new Button("画圆");
this.add(b);
b.setBounds(30,30,50,50);
b.addActionListener(this);
this.addWindowListener(new WindowAdapter () {
@Override
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
this.setBounds(200,200,500,400);
this.setVisible(true);
}
public void actionPerformed(ActionEvent e) {
this.cc = Color.red;
this.x = r.nextInt(400);
do {
int x1 = r.nextInt(300);
this.y = x1;
} while (this.y 50);
this.repaint();
}
@Override
public void paint(Graphics g) {
Color c = g.getColor();
g.setColor(cc);
g.drawRect(x,y,50,50);
g.setColor(c);
}
}