Java小程序之高级画板重绘篇I

Java小程序之高级画板重绘篇I

前言：我们完成的高级画板在最小化后，然后最大化，画板上绘制的图形全都会消失不见了。原因已在前面的博客中解释，这里不再累赘；今天就让我们一起来解决这个小bug吧！

画板重绘思路：
1、定义直线，椭圆，矩形，圆角矩形等类；
2、在绘制图形的时候生成相应的对象；
3、利用容器将对象进行保存；
4、利用重绘方法，将容器中的对象拿出来，进行重绘；

难点：容器中装了各种各样的对象，如何判断取出来的是什么对象？
                利用instanceof关键字解决
            重绘时如何把颜色和粗细进行重绘？
               
在保存对象的时候，把画笔的颜色和、粗细一并保存到对象中

附：工具中的图片以上传到我的资源；需要的可以自行下载；

源代码：

Line类：

package com.huaxin.zhou;

import java.awt.Color;
import java.awt.Stroke;

public class Line {

public int x1, y1, x2, y2;
public Color color;

public Stroke s;

public Line(int x1, int y1, int x2, int y2,Color color,Stroke s){
//保存直线的坐标
this.x1=x1;
this.y1=y1;

this.x2=x2;
this.y2=y2;

this.color=color;//保存直线的颜色
this.s=s;//保存直线的粗细
}

}

Rect类：

package com.huaxin.zhou;

import java.awt.Color;
import java.awt.Stroke;

public class Rect {

public int x1, y1, x2, y2;
public Color color;
public Stroke s;

public Rect(int x1, int y1, int x2, int y2,Color color, Stroke s){

this.x1=x1;
this.y1=y1;

this.x2=x2;
this.y2=y2;
this.color=color;
this.s=s;
}
}

RonundRect类：

package com.huaxin.zhou;

import java.awt.Color;
import java.awt.Stroke;

public class RoundRect {

public int x1, y1, x2, y2,i,j;
public Color color;
public Stroke s;

public RoundRect(int x1, int y1, int x2, int y2,int i,int j,Color color, Stroke s){

this.x1=x1;
this.y1=y1;

this.x2=x2;
this.y2=y2;

this.i=i;
this.j=j;

this.color=color;
this.s=s;
}

}

Oval类：

package com.huaxin.zhou;

import java.awt.Color;
import java.awt.Stroke;

public class Oval {

public int x1, y1, x2, y2;

public Color color;
public Stroke s;

public Oval(int x1, int y1, int x2, int y2,Color color,Stroke s){

this.x1=x1;
this.y1=y1;

this.x2=x2;
this.y2=y2;
this.color=color;
this.s=s;
}
}

Point类：

package com.huaxin.zhou;

import java.awt.Color;
import java.awt.Stroke;

public class Point {

public int x1, y1;
public Color color;

public Stroke s;

public Point(int x1, int y1,Color color,Stroke s){

this.x1=x1;
this.y1=y1;
this.color=color;
this.s=s;
}
}

DrawListener类：

package com.huaxin.zhou;

import java.awt.AWTException;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Stroke;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import java.util.Random;

import javax.swing.ButtonGroup;
import javax.swing.ButtonModel;

public class DrawListener implements MouseListener,MouseMotionListener{

public Graphics2D g;
public int x1,x2,y1,y2,old_x,old_y,x4,y4;
public ButtonGroup bg;
public String command;
public ArrayList list;

public Random r = new Random();

public boolean flag=true;

//持有对方引用
public Mypaint db;
public Color color;

//重载DrawListener方法

public DrawListener(Graphics g,ButtonGroup bg,Mypaint db1,ArrayList list){
this.g=(Graphics2D )g;
this.bg=bg;
db=db1;
this.list=list;
}

//鼠标按下时间
public void mousePressed(MouseEvent e) {
x1=e.getX();
y1=e.getY();

//确认是哪个按钮按下
ButtonModel bm= bg.getSelection();
command=bm.getActionCommand();

Stroke s1=new BasicStroke(1);

g.setStroke(s1);

if("pic7".equals(command)){

Stroke s=new BasicStroke(10);
g.setStroke(s);
}

}

public void mouseReleased(MouseEvent e) {

int x=e.getXOnScreen();
int y=e.getYOnScreen();

x2=e.getX();
y2=e.getY();

//如果是直线按钮按下，画直线
if("pic10".equals(command)){
g.drawLine(x1, y1, x2, y2);
Line line = new Line(x1, y1, x2, y2,g.getColor(),g.getStroke());//保存绘制的直线
list.add(line);
//如果是矩形按钮按下，画矩形
}else if("pic12".equals(command)){
//矩形的画法的纠正
g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
Rect rect = new Rect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1),g.getColor(),g.getStroke());
list.add(rect);
}else if("pic14".equals(command)){
//椭圆画法的纠正
g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
Oval oval = new Oval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1),g.getColor(),g.getStroke());
list.add(oval);
}

//画曲线
else if("pic13".equals(command)){
if(flag){
g.drawLine(x1, y1, x2, y2);
Line line = new Line(x1, y1, x2, y2,g.getColor(),g.getStroke());
list.add(line);
flag=false;
//记录第一次按下的x和y的坐标
x4=x1;
y4=y1;
}
else {
g.drawLine(old_x,old_y, x2, y2);
Line line = new Line(old_x,old_y, x2, y2,g.getColor(),g.getStroke());
list.add(line);
}

old_x=x2;
old_y=y2;
}

//取色功能
else if("pic4".equals(command)){
try {
Robot robot = new Robot();
Rectangle rect = new Rectangle(x,y,1,1);

BufferedImage bi=robot.createScreenCapture(rect);
int c=bi.getRGB(0, 0);
Color bicolor=new Color(c);
db.color=bicolor;

} catch (AWTException e1) {
e1.printStackTrace();
}
}
//圆角矩形功能
else if("pic15".equals(command)){
g.drawRoundRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1),10, 10);
RoundRect roundrect = new RoundRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1),10, 10,g.getColor(),g.getStroke());
list.add(roundrect);
}

}

public void mouseClicked(MouseEvent e) {
int count=e.getClickCount();
if("pic13".equals(command) && count==2){
g.drawLine(x4, y4, x2, y2);
Line line = new Line(x4, y4, x2, y2,g.getColor(),g.getStroke());
list.add(line);
flag=true;
}
}

public void mouseEntered(MouseEvent e) {
// 拿到画笔颜色
color=db.color;

//设置画笔颜色
g.setColor(color);

}

public void mouseExited(MouseEvent e) {

}

public void mouseDragged(MouseEvent e) {
//拿到当前的坐标
x2=e.getX();
y2=e.getY();

//铅笔画线
if("pic6".equals(command)){
g.drawLine(x1, y1, x2, y2);

Line line = new Line(x1, y1, x2, y2,g.getColor(),g.getStroke());
list.add(line);

x1=x2;
y1=y2;
}

//画粗线线
else if("pic7".equals(command)){
g.drawLine(x1, y1, x2, y2);

Line line = new Line(x1, y1, x2, y2,g.getColor(),g.getStroke());
list.add(line);
x1=x2;
y1=y2;
}
//橡皮擦功能实现
else  if("pic2".equals(command)){
g.setColor(Color.white);
Stroke bs = new BasicStroke(15);
g.setStroke(bs);
g.drawLine(x1, y1, x2, y2);
Line line =new Line(x1, y1, x2, y2,g.getColor(),g.getStroke());
list.add(line);
x1=x2;
y1=y2;

}

//喷桶功能
else if("pic8".equals(command)){

for(int i=0;i<30;i++){
int xp=r.nextInt(21)-10;
int yp=r.nextInt(21)-10;
g.drawLine(x2+xp, y2+yp, x2+xp, y2+yp);
Point point = new Point(x2+xp,y2+yp,g.getColor(),g.getStroke());
list.add(point);
}

}

}

public void mouseMoved(MouseEvent arg0) {

}

}

ButtonListener类：

package com.huaxin.zhou;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;

//按钮监听器类
public class ButtonListener implements ActionListener{

//持有对方引用，可以拿到对方的所有属性
public Mypaint db;

//常在方法
public ButtonListener(Mypaint db1){
db=db1;
}

//按钮监听事件的具体实现

public void actionPerformed(ActionEvent e) {

JButton bt =(JButton)e.getSource();
Color c=bt.getBackground();
db.color=c;
db.btt.setBackground(c);
}

}

MyPaint类：

package com.huaxin.zhou;

import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Stroke;
import java.util.ArrayList;

import javax.swing.ButtonGroup;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.BevelBorder;

public class Mypaint extends JFrame{

public ArrayList list = new ArrayList();

public Color color=Color.BLACK;

public JButton btt;

public void initFrame(){
//设置窗体属性
this.setSize(600,500);
this.setDefaultCloseOperation(3);
this.setTitle("我的画板");
this.setLocationRelativeTo(null);
//给窗体添加主面板
JPanel panel = new JPanel();
//设置窗体布局
panel.setLayout(new BorderLayout());
//添加主面板
this.add(panel);

//给窗体添加菜单
JMenuBar bar= new JMenuBar();
panel.add(bar,BorderLayout.NORTH);
String []str={"文件","视图","帮助","查看"};
String []str1={"打开文件","查看文件","帮助","查看"};
for(int i=0;i<4;i++){
JMenu menu = new JMenu(str[i]);
for(int j=0;j<4;j++){
JMenuItem item = new JMenuItem(str1[j]);
menu.add(item);
}
bar.add(menu);
}

//添加中间面板
JPanel panelcenter = new JPanel();
panelcenter.setLayout(new FlowLayout(FlowLayout.LEFT,10,10));
panel.setBackground(Color.gray);

panel.add(panelcenter);

//添加中间面板的子面板
JPanel panelcenterchild = new JPanel(){
//画板重绘
public void paint(Graphics g1) {
super.paint(g1);
Graphics2D g=(Graphics2D)g1;
for (int i = 0; i <list.size(); i++) {
//如果容器中使直线对象，则重新绘制直线
if(list.get(i) instanceof Line){
Line line = (Line)list.get(i);
g.setColor(line.color);
Stroke s =(BasicStroke)(line.s);
g.setStroke(s);
g.drawLine(line.x1, line.y1, line.x2, line.y2);
}
//重新绘制矩形
else if(list.get(i) instanceof Rect){
Rect rect = (Rect)list.get(i);
g.setColor(rect.color);
Stroke s =(BasicStroke)(rect.s);
g.setStroke(s);
g.drawRect(rect.x1, rect.y1,rect.x2, rect.y2);
}//重绘椭圆
else if(list.get(i) instanceof Oval){
Oval oval = (Oval)list.get(i);
g.setColor(oval.color);
Stroke s =(BasicStroke)(oval.s);
g.setStroke(s);
g.drawOval(oval.x1, oval.y1, oval.x2, oval.y2);
}
//喷桶重绘
else if(list.get(i) instanceof Point){
Point point = (Point)list.get(i);
g.setColor(point.color);
Stroke s =(BasicStroke)(point.s);
g.setStroke(s);
g.drawLine(point.x1, point.y1,point.x1,point.y1);
}
//圆角矩形重绘
else if(list.get(i) instanceof RoundRect){
RoundRect rr = (RoundRect)list.get(i);
g.setColor(rr.color);
Stroke s =(BasicStroke)(rr.s);
g.setStroke(s);
g.drawRoundRect(rr.x1,rr.y1,rr.x2,rr.y2,rr.i,rr.j);
}
}
}

};
panelcenterchild.setBackground(Color.WHITE);
panelcenterchild.setPreferredSize(new Dimension(500,330));
panelcenter.add(panelcenterchild);

//添加左边面板
JPanel panelleft = new JPanel();
panelleft.setLayout(new FlowLayout(FlowLayout.LEFT,0,0));
panelleft.setBackground(new Color(235,233,238));
panelleft.setPreferredSize(new Dimension(50, 0));

//给左边面板添加按钮
ButtonGroup bg = new ButtonGroup();
for(int i=0;i<16;i++){
//给每个按钮添加四种不同的图片
ImageIcon img1 = new ImageIcon("images/draw"+i+".jpg");
ImageIcon img2 = new ImageIcon("images/draw"+i+"-1"+".jpg");
ImageIcon img3 = new ImageIcon("images/draw"+i+"-2"+".jpg");
ImageIcon img4 = new ImageIcon("images/draw"+i+"-3"+".jpg");
JRadioButton jrb = new JRadioButton();
jrb.setActionCommand("pic"+i);

//设置默认选中项
if(i==10){
jrb.setSelected(true);
}

bg.add(jrb);

jrb.setIcon(img1);//设置默认图谱按
jrb.setRolloverIcon(img2);//设置鼠标停留在按钮上的图片
jrb.setPressedIcon(img3);//设置鼠标按下按钮的图谱按
jrb.setSelectedIcon(img4);//设置鼠标选中按钮的图片
jrb.setBorder(null);//设置按钮的边框为空，按钮凹下去效果
panelleft.add(jrb);
}

//下边面板
JPanel paneldown = new JPanel();
paneldown.setBackground(Color.gray);
paneldown.setLayout(null);
paneldown.setPreferredSize(new Dimension(0, 80));

//下边面板的子面板
JPanel paneldownchild = new JPanel();
paneldownchild.setLayout(null);
paneldownchild.setBounds(15, 10, 300, 60);
paneldownchild.setBackground(Color.green);

//子面板中的左面板
JPanel downleft = new JPanel();
downleft.setLayout(null);
downleft.setBackground(Color.white);
downleft.setBounds(0, 0, 60, 60);

//子面板中的右面板
JPanel downright = new JPanel();
downright.setBackground(Color.magenta);
downright.setLayout(new FlowLayout(FlowLayout.LEFT,0,0));
downright.setBounds(60, 0, 240, 60);

//子面板添加到相应的父面板中
panel.add(panelleft,BorderLayout.WEST);
panel.add(paneldown, BorderLayout.SOUTH);

paneldown.add(paneldownchild);
paneldownchild.add(downleft);
paneldownchild.add(downright);

//面板中添加两个颜色按钮
btt = new JButton();
btt.setBackground(Color.black);
btt.setBounds(10, 10, 30, 30);

JButton bt1 = new JButton();
bt1.setBackground(Color.white);
bt1.setBounds(25, 25, 30, 30);
downleft.add(btt);
downleft.add(bt1);

//设置按钮特效
BevelBorder  bb = new BevelBorder(0,Color.gray,Color.white);
BevelBorder  bb1 = new BevelBorder(1,Color.gray,Color.white);

downleft.setBorder(bb);
btt.setBorder(bb1);
bt1.setBorder(bb1);

//给添加右面板颜色按钮
ButtonListener bl= new ButtonListener(this);//按钮监听器

Color colors[] ={Color.BLUE,Color.red,Color.black,Color.ORANGE,Color.gray,
Color.CYAN,Color.GREEN,Color.YELLOW,Color.PINK,Color.magenta,new Color(234,45,78),new Color(67,123,9)};

for(int i=0;i<12;i++){
JButton bt3 = new JButton();
bt3.setBackground(colors[i]);
bt3.setBorder(bb);
bt3.setPreferredSize(new Dimension(40,30));
//给每个按钮添加按钮监听器
bt3.addActionListener(bl);
downright.add(bt3);
}

this.setVisible(true);

//拿到白色画板的画笔
Graphics g=panelcenterchild.getGraphics();

DrawListener dl = new DrawListener(g,bg,this,list);

//白色画板添加
panelcenterchild.addMouseListener(dl);
panelcenterchild.addMouseMotionListener(dl);

}

}

测试类：

package com.huaxin.zhou;

public class Test {

//主函数，用来测试
public static void main(String[] args) {
Mypaint paint = new Mypaint();
paint.initFrame();
}

}

好了，现在将我们的高级画板最小化后再最大化，刚才绘制的图形都会还会在哟！

总结：
1、重点在DrawListener类中和MyPaint中，DrawListener中，每绘制一个图形，要new相应的一个对象，并将该对象添加到容器中进行保存；MyPaint中，需要在peanelcenterchild中重写paint方法，利用for循环，挨次将容器中的对象取出来，判断取出来的对象类型，根据对象类型进行图形的重绘
2、容器中返回的类型是Object类型，利用instanceof关键字可以判断该对象是否可以转换成某一对象；如果该对象可以转换成直线类型，那么就将取出来的对象进行直线的重绘；以此类推；