⽤java画布画玫瑰花RoseCanvas类package yan03;import java.awt.Canvas;import java.awt.Color;import java.awt.Graphics;public class RoseCanvas extends Canvas //四叶玫瑰线画布组件{private Color color; //颜⾊public RoseCanvas(Color color){this.setColor(color);}public void setColor(Color color){this.color = color;}public void paint(Graphics g) //在Canvas上作图{int x0 = this.getWidth()/2; //(x0,y0)是组件正中点坐标int y0 = this.getHeight()/2;g.setColor(this.color); //设置画线颜⾊g.drawLine(x0,0,x0,y0*2); //画X轴g.drawLine(0,y0,x0*2,y0); //画Y轴for (int j=40; j<200; j+=20) //画若⼲圈四叶玫瑰线for (int i=0; i<1023; i++) //画⼀圈四叶玫瑰线的若⼲点{double angle = i*Math.PI/512;double radius = j*Math.sin(2*angle); //四叶玫瑰线int x =(int)Math.round(radius * Math.cos(angle)*2);int y =(int)Math.round(radius * Math.sin(angle));g.fillOval(x0+x,y0+y,2,2); //画直径为1的圆就是⼀个点}}}RoseJFrame类package yan03;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class RoseJFrame extends JFrame implements ActionListener{private RoseCanvas canvas; //⾃定义画布组件public RoseJFrame(){super("四叶玫瑰线"); //框架边布局Dimension dim=this.getToolkit().getScreenSize(); //获得屏幕分辨率this.setBounds(dim.width/4,dim.height/4,dim.width/2,dim.height/2); //窗⼝居中this.setDefaultCloseOperation(EXIT_ON_CLOSE);JPanel jpanel = new JPanel(); //⾯板流布局，居中this.getContentPane().add(jpanel,"North");JButton button_color = new JButton("选择颜⾊");jpanel.add(button_color);button_color.addActionListener(this);this.canvas = new RoseCanvas(Color.red); //创建⾃定义画布组件this.getContentPane().add(this.canvas,"Center");this.setVisible(true);}public void actionPerformed(ActionEvent ev) //按钮动作事件处理⽅法{Color c=JColorChooser.showDialog(this,"选择颜⾊",Color.blue); //弹出JColorChooser颜⾊选择对话框，返回选中颜⾊this.canvas.setColor(c);this.canvas.repaint(); //调⽤canvas的paint(Graphics)⽅法，重画public static void main(String arg[]){new RoseJFrame();}}RoseNJFrame类package yan03;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class RoseNJFrame extends JFrame implements ActionListener,ComponentListener{private JRadioButton radiobutton[]; //单选按钮private JCheckBox checkbox; //复选框private RoseNCanvas canvas; //⾃定义画布组件public RoseNJFrame(){super("多叶玫瑰线"); //框架边布局Dimension dim=getToolkit().getScreenSize(); //获得屏幕分辨率this.setBounds(dim.width/4,dim.height/4,dim.width/2,dim.height/2); //窗⼝居中this.setDefaultCloseOperation(EXIT_ON_CLOSE);this.addComponentListener(this); //注册组件事件监听器JToolBar toolbar=new JToolBar(); //创建⼯具栏，默认⽔平⽅向this.getContentPane().add(toolbar,"North"); //⼯具栏添加到框架内容窗格北部String rosestr[]={"⼀叶","四叶","三叶","⼋叶","五叶","⼗⼆叶","七叶","⼗六叶","九叶"};ButtonGroup bgroup = new ButtonGroup(); //按钮组radiobutton = new JRadioButton[rosestr.length]; //单选按钮数组for (int i=0; i<radiobutton.length; i++){radiobutton[i]=new JRadioButton(rosestr[i]); //单选按钮radiobutton[i].addActionListener(this);bgroup.add(radiobutton[i]); //单选按钮添加到按钮组toolbar.add(radiobutton[i]); //单选按钮添加到⼯具栏}radiobutton[0].setSelected(true); //设置单选按钮的选中状态checkbox = new JCheckBox("Y轴",false); //复选框toolbar.add(checkbox);checkbox.addActionListener(this); //复选框注册动作事件监听器JButton button_color = new JButton("选择颜⾊");toolbar.add(button_color);button_color.addActionListener(this);canvas = new RoseNCanvas(1,Color.red); //创建⾃定义画布组件this.getContentPane().add(canvas,"Center");this.setVisible(true);}public void actionPerformed(ActionEvent e) //按钮动作事件处理⽅法{if (e.getSource() instanceof JRadioButton) //选择⼀个颜⾊复选框for (int i=0; i<radiobutton.length; i++)if (e.getSource()==radiobutton[i]){canvas.setLeaf(i+1);break;}if (e.getSource()==checkbox){canvas.setAxis(checkbox.isSelected());if (e.getActionCommand().equals("Y轴"))checkbox.setText("X轴");elsecheckbox.setText("Y轴");}if (e.getActionCommand().equals("选择颜⾊")){Color c=JColorChooser.showDialog(this,"选择颜⾊",Color.blue); //弹出JColorChooser颜⾊选择对话框，返回选中颜⾊ canvas.setColor(c);}canvas.repaint(); //重画}public void componentResized(ComponentEvent e) //改变组件⼤⼩时canvas.repaint(); //重画}public void componentMoved(ComponentEvent e) {}public void componentHidden(ComponentEvent e) {}public void componentShown(ComponentEvent e) {}public static void main(String arg[]){new RoseNJFrame();}}class RoseNCanvas extends Canvas //画布组件{private int leaf; //多叶玫瑰线的叶数private boolean axis; //轴，默认Y轴private Color color; //颜⾊public RoseNCanvas(int leaf, Color color){this.axis = false;this.setLeaf(leaf);this.setColor(color);}void setLeaf(int leaf){this.leaf = leaf;}void setAxis(boolean axis){this.axis = axis;}void setColor(Color color){this.color = color;}public void paint(Graphics g) //在Canvas上作图{int x0 = this.getWidth()/2; //(x0,y0)是组件正中点坐标int y0 = this.getHeight()/2;g.setColor(this.color); //设置画线颜⾊g.drawLine(x0,0,x0,y0*2); //画X轴g.drawLine(0,y0,x0*2,y0); //画Y轴for (int j=40; j<200; j+=20) //画若⼲圈多叶玫瑰线for (int i=0; i<1023; i++) //画⼀圈多叶玫瑰线的若⼲点 {double angle = i*Math.PI/512, radius;if (!axis)radius = j*Math.sin(this.leaf*angle); //多叶玫瑰线沿X轴elseradius = j*Math.cos(this.leaf*angle); //多叶玫瑰线沿Y轴int x =(int)Math.round(radius * Math.cos(angle));int y =(int)Math.round(radius * Math.sin(angle));g.fillOval(x0+x,y0+y,2,2); //画直径为1的圆就是⼀个点 }}}。
