Question

GUI画图板（绘图板）设计，用Java编写程序代码！！谢谢！！

实验内容：
画板程序至少要实现如下功能：
1、使用ComboBox列出可以绘制的图形（至少包括点、线、矩形、圆形、圆弧），用户可以使用组合框选择要绘制的图形；

提供一组按钮（13个）可以让用户直接选择要使用的颜色，设置按钮打开JColorChooser帮助用户实现颜色的自定义平；

提供按钮或其他组件让用户设置当前图形是否填充。

2、实现使用鼠标点击对画板中的图形选中的功能；

提供橡皮擦按钮擦除处于选定状态的图形；

处于选定状态的图形还可以在鼠标左键按下（在选中图形区域内）的状态下被拖动。

3、图形的创建通过用户在绘图区内拖动和点击鼠标来实现。

实验提示：绘制请在JPanel的子类中进行；界面设计请不要使用IDE工具来进行，最好使用布局管理器设计一个可适用于不同分辨率显示的窗口。
实验扩展：
1、尝试为窗口设计菜单栏和工具栏，上下文菜单也可尝试实现；
2、图形创建过程的动态显示（也就是在鼠标拖动过程中动态显示将要创建的图形边框）；
3、尝试保存和读取图像（自己设计文件结构或者使用标准图像文件格式）；
4、减少绘图过程窗口的闪烁。

Answer 1

只有矩形有圆形能移动，其它实现起来麻烦点，办法有的只是代码太多。
画圆弧改成了画曲线，圆弧稍麻烦，当然方法是很简单的，你可以自己思考一下。
双击13个颜色中的任意一个都会弹出颜色选择器。
有保存与打开功能。扩展名请用 .jdr
基本满足条件，细节可能不是很好，另，代码比较乱，怕不好看懂咯，呼呼。

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.ArrayList;
import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter;

public class JDraw {
public static void main(String[] args) {
JFrame f=new JFrame();
f.setDefaultCloseOperation(3);
f.setSize(880,600);
f.setLocationRelativeTo(null);
f.getContentPane().add(M.c);
f.getContentPane().add(M.m,"South");
f.setVisible(true);
}
}

class CVS extends Component implements ComponentListener,MouseListener,MouseMotionListener{
public void componentHidden(ComponentEvent e) {}
public void componentMoved(ComponentEvent e) {}
public void componentResized(ComponentEvent e) {resized();}
public void componentShown(ComponentEvent e) {}
private void resized() {
int w=this.getWidth();
int h=this.getHeight();
tbuff=new BufferedImage(w,h,3);
makeBuff(w,h);
}
private void makeBuff(int w,int h) {
Graphics g = tbuff.getGraphics();
g.drawImage(buff,0,0,null);
g.dispose();
buff=new BufferedImage(w,h,3);
g=buff.getGraphics();
g.drawImage(tbuff,0,0,null);
g.dispose();
}

BufferedImage buff,tbuff;
CVS(){
this.addComponentListener(this);
this.addMouseListener(this);
this.addMouseMotionListener(this);
buff=new BufferedImage(1,1,3);
}

public void paint(Graphics gr){
Graphics2D g = buff.createGraphics();
g.setBackground(new Color(0xff000000,true));
g.clearRect(0,0,getWidth(),getHeight());
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
M.sa.drawAll(g);
if(M.ts!=null)
M.ts.draw(g);
g.dispose();
gr.drawImage(buff,0,0,this);
gr.dispose();
}
public void mouseClicked(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public void mousePressed(MouseEvent e) {
M.mp(e.getPoint());
}
public void mouseReleased(MouseEvent e) {
M.mr(e.getPoint());
}
public void mouseDragged(MouseEvent e) {
M.md(e.getPoint());
}
public void mouseMoved(MouseEvent e) {}
}
class Menu extends JComponent implements MouseListener,ActionListener{
JComboBox sbox,method;
CLabel[] cl;
JCheckBox fillC,drawB;
JRadioButton fc,bc;
ButtonGroup bg;
JButton clear,up,down,save,load;
Menu(){
this.setLayout(new FlowLayout());
method=new JComboBox(new Object[]{"draw","move","erase",});
add(method);
sbox=new JComboBox(new Object[]{"Pt","Ln","Rect","Cir","Arc",});
add(sbox);
cl=new CLabel[13];
for(int i=0; i<cl.length; i++){
cl[i]=new CLabel();
cl[i].addMouseListener(this);
add(cl[i]);
}
fc=new JRadioButton("fc",true);
bc=new JRadioButton("bc");
bg=new ButtonGroup();
bg.add(fc);bg.add(bc);
add(fc);add(bc);
fc.setOpaque(true);
bc.setOpaque(true);
fc.setBackground(Color.white);
bc.setBackground(Color.blue);
fillC=new JCheckBox("Fill",true);
drawB=new JCheckBox("Draw",true);
fillC.addActionListener(this);
drawB.addActionListener(this);
add(fillC);add(drawB);
clear=new JButton("clear");
clear.addActionListener(this);
add(clear);
up=new JButton("zUp");
up.addActionListener(this);
add(up);
down=new JButton("zDown");
down.addActionListener(this);
add(down);
save=new JButton("Save");
save.addActionListener(this);
add(save);
load=new JButton("Load");
load.addActionListener(this);
add(load);
}
public void mouseClicked(MouseEvent e) {
JLabel l=(JLabel)e.getSource();
if(e.getClickCount()==2){
Color sc=JColorChooser.showDialog(null, "Color chooser", l.getBackground());
l.setBackground(sc);
mousePressed(e);
}
}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public void mousePressed(MouseEvent e) {
Color c=((JLabel)e.getSource()).getBackground();
if(fc.isSelected())
fc.setBackground(c);
else if(bc.isSelected())
bc.setBackground(c);
M.cp();
}
public void mouseReleased(MouseEvent e) {}
public void actionPerformed(ActionEvent e) {
if(e.getSource()==clear)M.clear();
else if(e.getSource()==up)M.up();
else if(e.getSource()==down)M.down();
else if(e.getSource()==save)M.save();
else if(e.getSource()==load)M.load();
else if(e.getSource()==fillC||e.getSource()==drawB)M.cp();
}
}
class CLabel extends JLabel{
static Color[] cs={Color.red,Color.orange,Color.yellow,Color.green,Color.cyan,
Color.blue,Color.magenta,Color.magenta.brighter(),
Color.white,Color.black,Color.gray,Color.LIGHT_GRAY,Color.DARK_GRAY,};
static int i;
CLabel(){
this.setOpaque(true);
this.setBackground(cs[i++]);
this.setBorder(BorderFactory.createLineBorder(Color.black));
this.setPreferredSize(new Dimension(10,20));
}
}
class M{
static JFileChooser jfc=new JFileChooser();
static Menu m=new Menu();
static CVS c=new CVS();
static SA sa=new SA();
static S ts=null,selected=null;
static Color fc,bc;
static void clear(){
sa.ss.clear();
c.repaint();
}
public static void cp() {
System.out.println(selected);
if(selected!=null){
selected.fillColor=m.fc.getBackground();
selected.borderColor=m.bc.getBackground();
selected.fc=m.fillC.isSelected();
selected.db=m.drawB.isSelected();
c.repaint();
}
}
public static void up() {
if(selected!=null){
sa.upZ(selected);
c.repaint();
}
}
public static void down(){
if(selected!=null){
sa.downZ(selected);
c.repaint();
}
}
static{
jfc.setFileFilter(new FileNameExtensionFilter("JDraw file (*.jdraw,*.jdr)","jdr","jdraw"));
}
static void save(){
int x=jfc.showSaveDialog(c);
if(x==JFileChooser.APPROVE_OPTION){
File f = jfc.getSelectedFile();
try{
ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream(f));
oos.writeObject(sa);
oos.flush();
oos.close();
}catch(Exception e){}
}
}
static void load(){
int x=jfc.showOpenDialog(c);
if(x==JFileChooser.APPROVE_OPTION){
File f = jfc.getSelectedFile();
try{
ObjectInputStream oos=new ObjectInputStream(new FileInputStream(f));
Object r=oos.readObject();
if(r!=null){
sa=(SA)r;
c.repaint();
}
oos.close();
}catch(Exception e){e.printStackTrace();}
}
}
static int mx,my,tx,ty,ox,oy;
static int pc=0,pmax;
static int sm;
static boolean ne=true;
static int mid;
static void mp(Point p){
mid=m.method.getSelectedIndex();
if(mid==0){
if(ne){
mx=p.x;my=p.y;
pc=0;
sm=m.sbox.getSelectedIndex();
pmax=sm==4?2:1;
ne=false;
}
++pc;
}
else if(mid==1){
checkSel(p);
mx=p.x;my=p.y;
}
else if(mid==2){
checkSel(p);
if(selected!=null){
sa.ss.remove(selected);
c.repaint();
}
}
}
private static void checkSel(Point p) {
selected=null;
for(int i=sa.ss.size();i>0; i--)
if(sa.ss.get(i-1).shape.contains(p)){
selected=sa.ss.get(i-1);break;
}
sa.select(selected);
c.repaint();
}
static void mt(){
Shape s=null;
int cx,cy,cw,ch;
switch(sm){
case 0:
case 2:
cx=Math.min(mx,tx);
cy=Math.min(my,ty);
cw=Math.abs(mx-tx);
ch=Math.abs(my-ty);
if(sm==0)
s=new Ellipse2D.Double(cx,cy,cw,ch);
else
s=new Rectangle(cx,cy,cw,ch);
break;
case 1:
s=new Line2D.Float(mx,my,tx,ty);
break;
case 3:
cw=Math.abs(mx-tx);
ch=Math.abs(my-ty);
int cd=(int)Math.sqrt(Math.pow(mx-tx,2)+Math.pow(my-ty,2))*2;
cx=mx-cd/2;
cy=my-cd/2;
s=new Ellipse2D.Double(cx,cy,cd,cd);
break;
case 4:
Path2D p=new Path2D.Double();
p.moveTo(mx,my);
if(pc==1){
p.lineTo(tx, ty);
}
else{
p.quadTo(ox,oy,tx,ty);
}
s=p;
break;
}
ts=new S(s,m.fc.getBackground(),m.bc.getBackground(),m.fillC.isSelected(),m.drawB.isSelected(),null);
c.repaint();
}
static void md(Point p){
if(mid==0){
if(!sa.ss.isEmpty()){
sa.ss.get(sa.ss.size()-1).sel=false;
}
if(pc>1){
ox=p.x;oy=p.y;
}
else{
tx=p.x;ty=p.y;
}
mt();
}
else if(mid==1){
if(selected!=null){
moveTo(selected,p);
c.repaint();
}
}
else if(mid==2){
checkSel(p);
if(selected!=null){
sa.ss.remove(selected);
c.repaint();
}
}
}
static void moveTo(S s, Point p) {
if(s.shape instanceof Rectangle){
Rectangle r=(Rectangle)s.shape;
r.setLocation(r.x+p.x-mx,r.y+p.y-my);
mx=p.x;my=p.y;
}
else if(s.shape instanceof Ellipse2D){
Ellipse2D e=(Ellipse2D)s.shape;
e.setFrame(e.getX()+p.x-mx,e.getY()+p.y-my,e.getWidth(),e.getHeight());
mx=p.x;my=p.y;
}
}
static void mr(Point p) {
if(pc==pmax){
pc=0;
ne=true;
sa.add(ts);
selected=ts;
ts=null;
}
}
}

class S implements Serializable{
boolean fc,db,sel=true;
Shape shape;
Color fillColor,borderColor;
Stroke stroke;
static Stroke bstroke=new MyBasicStroke();
static Stroke selectStroke=new BasicStroke(1,BasicStroke.CAP_BUTT,BasicStroke.JOIN_MITER,1,new float[]{5,2},1);
S(Shape s,Color c,Color b,boolean f,boolean d,Stroke k){
this.shape=s;this.fillColor=c;this.borderColor=b;this.fc=f;this.db=d;this.stroke=k==null?bstroke:k;
}
void draw(Graphics2D g){
if(fc){
g.setColor(fillColor);
g.fill(shape);
}
if(db){
g.setColor(borderColor);
g.setStroke(stroke);
g.draw(shape);
}
if(sel){
g.setColor(Color.green);
g.setStroke(selectStroke);
g.draw(shape.getBounds());
}
}
}
class MyBasicStroke extends BasicStroke implements Serializable{}
class SA implements Serializable{
ArrayList<S> ss=new ArrayList<S>();
void add(S s){
if(s!=null){
for(S sx:ss)
sx.sel=false;
ss.add(s);
}
}
S remove(int i){
return ss.remove(i);
}
void remove(S s){
ss.remove(s);
}
void upZ(S s){
indexZ(s,1);
}
void downZ(S s){
indexZ(s,-1);
}
void indexZ(S s, int i) {
int si=ss.indexOf(s);
if(si+i<0||si+i>ss.size()-1)return;
swap(s,ss.get(si+i));
}
void swap(S a,S b){
int ai=ss.indexOf(a);
int bi=ss.indexOf(b);
ss.set(ai,b);
ss.set(bi,a);
}
void select(S s){
for(S x:ss)
x.sel=false;
if(s!=null)
s.sel=true;
}
void drawAll(Graphics2D g){
for(S s:ss)
s.draw(g);
}
}

Answer 2

这个做过，好简单的。