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基于java实现画图板功能

顺亿
顺亿
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本文实例为大家分享了java实现画图板功能的具体代码，供大家参考，具体内容如下

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;idrawlistener.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。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

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