java画图板功能
l0919160205 人气:0一、介绍
这个画图板主要实现的功能是画矩形（矩形使用的是一个函数画图的方法，这样画出来的图形比较有特点）、椭圆、多变形（先画一条直线，鼠标每点击一个地方就会从上一个点连接到点击的点，当鼠标双击时，双击的点会和终点和起点相连）、画线、橡皮以及颜色选择器，效果图如下所示：
二、具体实现
本项目主要使用的是java.swing以及java.awt的画图工具来实现。首先显示窗口的建立，先让主类draw继承javax.swing.JFrame。draw.java的代码如下：
public class draw extends JFrame{
private Shape shape[]= new Shape[100000];//将所画的形状存储在shape数组中
public static void main(String[] args) {
draw simpleDraw = new draw();
simpleDraw.showUI();//调用showUI()函数
}
public void showUI() {
drawlistener drawListener = new drawlistener();
java.awt.FlowLayout flowLayout = new FlowLayout();
JButton jb1=new JButton("矩形");//添加一个叫“矩形”的按钮
JButton jb2=new JButton("椭圆");
JButton jb3=new JButton("多边形");
JButton jb4=new JButton("三角形");
JButton jb5=new JButton("画线");
JButton jb6=new JButton("橡皮");
java.awt.Dimension dimension = new Dimension(100, 30);
jb1.setPreferredSize(dimension);//设置按钮的位置
jb2.setPreferredSize(dimension);
jb3.setPreferredSize(dimension);
jb4.setPreferredSize(dimension);
jb5.setPreferredSize(dimension);
jb6.setPreferredSize(dimension);
this.add(jb1);//在这个窗口上添加按钮
this.add(jb2);
this.add(jb3);
this.add(jb4);
this.add(jb5);
this.add(jb6);
Color []colors= {Color.BLUE,Color.GRAY,Color.YELLOW,Color.BLACK};//提供四种颜色选择，存储在colors数组中
for(int i=0;i<4;i++) {//新建4个颜色选择的按钮
JButton jButton=new JButton();
jButton.setBackground(colors[i]);
jButton.setPreferredSize(new Dimension(30, 30));
this.add(jButton);//在这个窗口上添加次按钮
jButton.addActionListener(drawListener);//设置按钮的位置
}
this.setLayout(flowLayout);//设置窗口布局
this.setSize(800, 700);//设置窗口大小
this.setTitle("画板");//设置窗口名称
this.setLocationRelativeTo(null);//设置窗口位置
this.setDefaultCloseOperation(3);
this.setVisible(true);
this.getContentPane().setBackground(Color.white);//设置窗口背景颜色
this.addMouseMotionListener(drawListener);//窗口添加监听
jb1.addActionListener(drawListener);//按钮添加监听
jb2.addActionListener(drawListener);
jb3.addActionListener(drawListener);
jb4.addActionListener(drawListener);
jb5.addActionListener(drawListener);
jb6.addActionListener(drawListener);
//-----------------
java.awt.Graphics g = this.getGraphics();//在此窗口上获得画笔
drawListener.setGr(g);//将画笔传给监听器drawListener
drawListener.setShape(shape);//将数组传给监听器drawListener
this.addMouseListener(drawListener);//画布添加监听
}
public void paint(Graphics g) {//重绘
super.paint(g);
for(int i=0;i<shape.length;i++) {//重绘shape数组中的所有图形
Shape shape1=shape[i];
if(shape1!=null) {
shape1.drawShape(g);
}else
break;
}
}
}上述代码中showUI()函数是画图板的界面，drawlistener drawListener = new drawlistener();是调用drawlistener.java新建一个drawlistener类。
在项目进行的过程中，将窗口最小化或者改变窗口大小时，我们先前画的东西就全部消失了。这是因为当窗体在屏幕上显示的时候，首先是将窗体对象的数据从内存中取出来放到缓存中，再在屏幕上进行绘制。当窗体发生改变的时候，程序就会重新从内存中获取更新后的数据绘制。**在系统中Jframe的父类中提供有一个paint（Graphics g）的方法来负责将窗口数据在屏幕上绘制出来。**所以我重写了paint（Graphics g）方法，先将画过的图形存储在一个shape数组中，然后在paint（Graphics g）方法中将所有图形重新画出来，代码：
public void paint(Graphics g) {//重绘
super.paint(g);
for(int i=0;i<shape.length;i++) {//重绘shape数组中的所有图形
Shape shape1=shape[i];
if(shape1!=null) {
shape1.drawShape(g);
}else
break;
}
}drawlistener.java代码如下：
public class drawlistener implements MouseListener,ActionListener,MouseMotionListener{
private int x1,x2,y1,y2,x3,y3,a,b,x4,y4;
private Graphics gr;
private int flag=1;
String name;
Shape shapeLarry[];
int index;
Color c=Color.BLACK;
public void setShape(Shape shape[]) {//传入shape数组
this.shapeLarry=shape;
}
public void setGr(Graphics graphics) {//传入画笔
gr=graphics;
}
public void mouseClicked(MouseEvent e) {//重写鼠标点击函数mouseClicked(MouseEvent e)
x3=e.getX();//获取鼠标x坐标
y3=e.getY();//获取鼠标y坐标
if("多边形".equals(name)) {//如果点击多边形按钮
if(flag == 2) {//如果是第一次画
//gr.drawLine(x3, y3, x1, y1);
gr.drawLine(x3, y3, x2, y2);
Shape shape=new Shape(x3, x2, y3, y2, name);
shape.setColor(c);
shapeLarry[index++]=shape;
a=x3;
b=y3;
flag++;
}
if(flag==3) {//如果不是第一次画
gr.drawLine(x3, y3, a, b);
Shape shape=new Shape(x3, a, y3, b, name);
shape.setColor(c);
shapeLarry[index++]=shape;
a=x3;
b=y3;
}
if(e.getClickCount()==2) {//如果双击，连接起点终点
gr.drawLine(x3, y3, x1, y1);
Shape shape=new Shape(x3, x1, y3, y1, name);
shape.setColor(c);
shapeLarry[index++]=shape;
gr.drawLine(x3, y3, a, b);
flag-=2;
}
}
if("三角形".equals(name)) {//如果点击三角形按钮
if(flag==2) {//如果不是第一次画，连接两端
gr.drawLine(x3, y3, x1, y1);
Shape shape=new Shape(x1, x3, y1, y3, name);
shape.setColor(c);
shapeLarry[index++]=shape;
gr.drawLine(x3, y3, x2, y2);
Shape shape2=new Shape(x2, x3, y2, y3, name);
shape2.setColor(c);
shapeLarry[index++]=shape2;
flag--;
}
}
System.out.println("flag="+flag);
}
public void mousePressed(MouseEvent e) {//重写鼠标持续点击函数mousePressed(MouseEvent e)
if(flag == 1) {
x1=e.getX();
y1=e.getY();
}
}
public void mouseReleased(MouseEvent e){//重写鼠标释放函数mouseReleased(MouseEvent e)
if(flag==1) {
x2=e.getX();
y2=e.getY();
}
if("矩形".equals(name)) {//使用函数画图
for(int i=0;i<25500;i++) {
gr.setColor(new Color(i/100, (i+12)/100, 12));
if((i+12)/100>=225) {
for(int i2=i;i2<30000;i2++) {
gr.setColor(new Color(i/100, (i+12)/100, 12));
if((Math.abs(x2-x1)-i2/50)<=0||(Math.abs(y2-y1)-i2/50)<=0)
break;
gr.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1)-i2/50, Math.abs(y2-y1)-i2/50);
}
break;
}
gr.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1)-i/50, Math.abs(y2-y1)-i/50);
}
Shape shape= new Shape(x1, x2, y1, y2, name);
shapeLarry[index++]=shape;
//gr.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
}
if("椭圆".equals(name)) {//当鼠标释放时画椭圆
gr.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
Shape shape=new Shape(x1, x2, y1, y2, name);
shape.setColor(c);
shapeLarry[index++]=shape;
}
if("多边形".equals(name) && flag==1) {//当鼠标释放时且不是最后一次画时画直线
gr.drawLine(x1, y1, x2, y2);
Shape shape=new Shape(x1, x2, y1, y2, name);
shape.setColor(c);
shapeLarry[index++]=shape;
flag++;
}
if("三角形".equals(name) && flag==1) {
gr.drawLine(x1, y1, x2, y2);
Shape shape=new Shape(x1, x2, y1, y2, name);
shape.setColor(c);
shapeLarry[index++]=shape;
flag++;
}
if("橡皮".equals(name)) {
Graphics2D graphics2d=(Graphics2D) gr;
BasicStroke basicStroke=new BasicStroke(1f);
graphics2d.setColor(c);
graphics2d.setStroke(basicStroke);
}
System.out.println("flag="+flag);
}
public void actionPerformed(ActionEvent e) {
if("".equals(e.getActionCommand())) {
JButton jb=(JButton)e.getSource();
c=jb.getBackground();
gr.setColor(c);
}else if("多边形".equals(e.getActionCommand())==false ||"三角形".equals(e.getActionCommand())==false){
flag=1;
name=e.getActionCommand();
}else {
name=e.getActionCommand();
}
}
public void mouseDragged(MouseEvent e) {//重写鼠标拖拽函数mouseDragged(MouseEvent e)
x4=e.getX();
y4=e.getY();
if("画线".equals(name)) {//画线主要是下一个点和上一个点连线组成
gr.drawLine(x1, y1,x4, y4);
Shape sh=new Shape(x4, y4, name, x1, y1);
sh.setColor(c);
shapeLarry[index++]=sh;
x1=x4;
y1=y4;
}
if("橡皮".equals(name)) {
Graphics2D graphics2d=(Graphics2D) gr;
BasicStroke basicStroke=new BasicStroke(10f);
graphics2d.setColor(Color.WHITE);
graphics2d.setStroke(basicStroke);
gr.drawLine(x1, y1,x4, y4);
Shape she=new Shape(x4, y4, name, x1, y1);
she.setColor(Color.white);
shapeLarry[index++]=she;
x1=x4;
y1=y4;
}
if("矩形".equals(name)) {
gr.drawRect(Math.min(x1, x4), Math.min(y1, y4), Math.abs(x4-x1), Math.abs(y4-y1));
gr.setColor(Color.white);
gr.drawRect(Math.min(x1, a), Math.min(y1, b), Math.abs(a-x1), Math.abs(b-y1));
gr.setColor(Color.black);
a=x4;
b=y4;
}
}
}Shape.java代码如下：
public class Shape {
private int x1,x2,y1,y2,x3,y3,x4,y4,a,b;
String name;
Color c1;
public Shape(int x1,int x2,int y1,int y2,String name) {
this.x1=x1;
this.x2=x2;
this.y1=y1;
this.y2=y2;
this.name=name;
}
public Shape(int x4,int y4,String name,int x1,int y1) {
this.x1=x1;
this.y1=y1;
this.x4=x4;
this.y4=y4;
this.name=name;
}
public void setColor(Color c) {
this.c1=c;
}
public void drawShape(Graphics g){
g.setColor(c1);
switch (name) {
case "矩形":
for(int i=0;i<25500;i++) {
g.setColor(new Color(i/100, (i+12)/100, 12));
if((i+12)/100>=225) {
for(int i2=i;i2<30000;i2++) {
g.setColor(new Color(i/100, (i+12)/100, 12));
if((Math.abs(x2-x1)-i2/50)<=0||(Math.abs(y2-y1)-i2/50)<=0)
break;
g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1)-i2/50, Math.abs(y2-y1)-i2/50);
}
break;
}
g.drawRect(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1)-i/50, Math.abs(y2-y1)-i/50);
}
break;
case "椭圆":
Graphics2D graphics2d4=(Graphics2D) g;
BasicStroke basicStroke4=new BasicStroke(1f);
graphics2d4.setColor(c1);
graphics2d4.setStroke(basicStroke4);
g.drawOval(Math.min(x1, x2), Math.min(y1, y2), Math.abs(x2-x1), Math.abs(y2-y1));
break;
case "画线":
Graphics2D graphics2d=(Graphics2D) g;
BasicStroke basicStroke=new BasicStroke(1f);
graphics2d.setColor(c1);
graphics2d.setStroke(basicStroke);
g.drawLine(x1, y1, x4, y4);
break;
case "橡皮":
Graphics2D g2D=(Graphics2D)g;
BasicStroke basicStroke2=new BasicStroke(10f);
g2D.setColor(Color.WHITE);
g2D.setStroke(basicStroke2);
g2D.drawLine(x1, y1,x4, y4);
break;
case "三角形":
Graphics2D graphics2d1=(Graphics2D) g;
BasicStroke basicStroke1=new BasicStroke(1f);
graphics2d1.setColor(c1);
graphics2d1.setStroke(basicStroke1);
g.drawLine(x1, y1, x2, y2);
//g.drawLine(x3, y3, x1, y1);
//g.drawLine(x3, y3, x2, y2);
break;
case "多边形":
Graphics2D graphics2d2=(Graphics2D) g;
BasicStroke basicStroke3=new BasicStroke(1f);
graphics2d2.setColor(c1);
graphics2d2.setStroke(basicStroke3);
g.drawLine(x1, y1, x2, y2);
break;
default:
break;
}
}
}shape类主要是用来存储画过的图形而定义的类型，将图形存储在shape类型的数组中就不会出现所画的图形消失的情况了。
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