代码可复现(多边形角形监听器矩形图形)

怎么样？如果觉得还不错的话就请继续看下去吧！
首先我们要写一个界面，就要给界面添加一个监听器，对监听器不太熟悉的同学，可以看我的这篇文章 常见监听器用法

package drawBoard_test;import javax.swing.;import java.awt.;public class DrawUI extends JFrame { String[] strs = {"直线","签字笔","实时直线", "谢尔宾斯基地毯","递归KLine","矩形", "圆", "实心矩形", "实心圆", "等腰三角形", "三角形", "多边形", "改进多边形","立方体", "橡皮擦", "撤回", "保存", "打开"}; Color[] color = {Color.red,Color.white,Color.black,Color.blue}; //添加功能和颜色按钮 public void addButton(){ for(String str : strs){ JButton btn = new JButton(str); add(btn); } Dimension dim = new Dimension(30,30); for(Color c : color){ JButton btn = new JButton(); btn.setBackground(c); btn.setPreferredSize(dim); add(btn); } } public void initUI(){ this.setTitle("画图板"); FlowLayout flow = new FlowLayout(); this.setLayout(flow); this.setSize(1000,800); this.setLocationRelativeTo(null); this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); this.addButton(); this.setVisible(true); Graphics g = getGraphics(); } public static void main(String[] args) { DrawUI drawUI = new DrawUI(); drawUI.initUI(); }}大家可以试着运行一下，出现以下效果，第一步就算成功了第二步：为窗体和按钮添加监听器首先要创建一个监听器，我们需要用到事件监听器ActionListener，和鼠标监听器MouseListener,MouseMotionListener，所以我们选择继承这三个接口， 我们都知道，继承一个接口时需要重写接口的所有方法，但是我们又不会使用到三个接口的所有方法(鼠标进入/离开组件)，所以我们可以先写一个类A继承所有接口，然后再用监听器类去继承类A。
监听器的父类：

package drawBoard_test;import java.awt.event.;public class DrawListenerFather implements ActionListener, MouseListener, MouseMotionListener { @Override public void actionPerformed(ActionEvent e) { } @Override public void mouseClicked(MouseEvent e) { } @Override public void mousePressed(MouseEvent e) { } @Override public void mouseReleased(MouseEvent e) { } @Override public void mouseEntered(MouseEvent e) { } @Override public void mouseExited(MouseEvent e) { } @Override public void mouseDragged(MouseEvent e) { } @Override public void mouseMoved(MouseEvent e) { }}

接下来，创建我们需要的监听器DrawListener,我们如果想在画图板上绘制的话，需要将主页面的画笔g传给监听器，所以我们给监听器添加成员变量Graphic g;并添加setG()方法。

package drawBoard_test;public class DrawListener extends DrawListenerFather { private Graphics g; public void setG(Graphics g) { this.g = g; } @Override public void actionPerformed(ActionEvent e) { } @Override public void mouseClicked(MouseEvent e) { } @Override public void mousePressed(MouseEvent e) { } @Override public void mouseReleased(MouseEvent e) { } @Override public void mouseEntered(MouseEvent e) { } @Override public void mouseDragged(MouseEvent e) { } @Override public void mouseMoved(MouseEvent e) { }}我们将主窗体的画笔g传给监听器，并为主窗体以及它的所有按钮以及加上监听器。
主窗体DrawUI中的代码更新为：

package drawBoard_test;import javax.swing.;import java.awt.;public class DrawUI extends JFrame { DrawListener dl = new DrawListener(); String[] strs = {"直线","签字笔","实时直线", "谢尔宾斯基地毯","递归KLine","矩形", "圆", "实心矩形", "实心圆", "等腰三角形", "三角形", "多边形", "改进多边形","立方体", "橡皮擦", "撤回", "保存", "打开"}; Color[] color = {Color.red,Color.white,Color.black,Color.blue}; public void addButton(){ for(String str : strs){ JButton btn = new JButton(str); btn.addActionListener(dl); //添加事件监听器 add(btn); } Dimension dim = new Dimension(30,30); for(Color c : color){ JButton btn = new JButton(); btn.setBackground(c); btn.setPreferredSize(dim); btn.addActionListener(dl); //添加事件监听器 add(btn); } } public void initUI(){ this.setTitle("画图板"); FlowLayout flow = new FlowLayout(); this.setLayout(flow); this.setSize(1000,800); this.setLocationRelativeTo(null); this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); this.addButton(); this.setVisible(true); this.addMouseListener (dl); this.addMouseMotionListener (dl);//添加鼠标监听器 Graphics g = getGraphics (); dl.setG(g); //将窗体的画笔g传入监听器 } public static void main(String[] args) { DrawUI drawUI = new DrawUI(); drawUI.initUI(); }}

接下来我们就可以去实现我们的绘图功能了！

我们在监听器中创建一个字符串shapeName，当点击按钮时，将按钮上的字符赋给shapeName，再根据shapeName的值来决定鼠标监听器的具体行为

package drawBoard_test;import javax.swing.;import java.awt.;import java.awt.event.ActionEvent;import java.awt.event.MouseEvent;public class DrawListener extends DrawListenerFather { private Graphics g; String shapeName = null; //按钮上的图形名称 String btn_action ; //按钮上的字符串 Color color; //记录当前画笔的颜色 int x2,y2,x3,y3; //存放坐标 public void setG(Graphics g) { this.g = g; } @Override public void actionPerformed(ActionEvent e) { / 有的小伙伴可能会有疑问，为什么要用btn_action做一个中间量呢？试想一下，如果我们直接使用switch(shapeName)，那么我们点击颜色按钮的时候 shapeName就会被换成空值""，我们就需要重新点击图形按钮再进行绘制。
/ btn_action = e.getActionCommand(); if(btn_action.equals("")){ JButton btn = (JButton) e.getSource(); //getSource方法获取触发此次事件的组件对象，返回值为Object类型 color = btn.getBackground(); //获取按钮组件的背景颜色 g.setColor(color); return; }else { shapeName = btn_action; } } @Override public void mousePressed(MouseEvent e) { x2 = e.getX(); y2 = e.getY(); } @Override public void mouseReleased(MouseEvent e) { x3 = e.getX(); y3 = e.getY(); if(shapeName == null) return; switch(shapeName){ case "直线": g.drawLine(x2, y2, x3, y3); break; } }}

此时，画图板可以绘制出直线，我们来看一下效果

实现直线的绘制之后，其余功能的实现也是水到渠成的，我们继续往下看。

package drawBoard_test;import javax.swing.;import java.awt.;import java.awt.event.ActionEvent;import java.awt.event.MouseEvent;public class DrawListener extends DrawListenerFather { private Graphics g; String shapeName = null; String btn_action ; Color color; int x2,y2,x3,y3; public void setG(Graphics g) { this.g = g; } @Override public void actionPerformed(ActionEvent e) { btn_action = e.getActionCommand(); //btn_action if(btn_action.equals("")){ JButton btn = (JButton) e.getSource(); color = btn.getBackground(); g.setColor(color); return; }else { shapeName = btn_action; } } @Override public void mousePressed(MouseEvent e) { x2 = e.getX(); y2 = e.getY(); } @Override public void mouseReleased(MouseEvent e) { x3 = e.getX(); y3 = e.getY(); if(shapeName == null) return; switch(shapeName){ case "直线": g.drawLine(x2, y2, x3, y3); break; case "矩形": g.drawRect(Math.min(x2,x3),Math.min(y2,y3),Math.abs(x3-x2),Math.abs(y3-y2)); break; case "圆" : g.drawOval(Math.min(x2,x3),Math.min(y2,y3),Math.abs(x3-x2),Math.abs(y3-y2)); break; case "谢尔宾斯基地毯" : Sierpinski(Math.min(x2,x3),Math.min(y2,y3),Math.abs(x3-x2),Math.abs(y3-y2)); break; case "递归KLine" : KLine(x2,y2,x3,y3,y3-y2); break; case "实心矩形" : g.fillRect(Math.min(x2,x3),Math.min(y2,y3),Math.abs(x3-x2),Math.abs(y3-y2)); break; case "实心圆" : g.fillOval(Math.min(x2,x3),Math.min(y2,y3),Math.abs(x3-x2),Math.abs(y3-y2)); break; case "等腰三角形" : g.drawLine(x2,y3,x3,y3); g.drawLine(x2,y3,(x2+x3)/2,y2); g.drawLine(x3,y3,(x2+x3)/2,y2); break; case "立方体" : g.drawRect(Math.min(x2,x3),Math.min(y2,y3),Math.abs(x3-x2),Math.abs(y3-y2)); g.drawLine(x2+(int)((x3-x2)1.414/4),y2-(int)((y3-y2)1.414/4),x2,y2); g.drawLine(x2+(int)((x3-x2)1.414/4),y2-(int)((y3-y2)1.414/4),x3+(int)((x3-x2)1.414/4),y2-(int)((y3-y2)1.414/4)); g.drawLine(x3,y2,x3+(int)((x3-x2)1.414/4),y2-(int)((y3-y2)1.414/4)); g.drawLine(x3+(int)((x3-x2)1.414/4),y3-(int)((y3-y2)1.414/4),x3+(int)((x3-x2)1.414/4),y2-(int)((y3-y2)1.414/4)); g.drawLine(x3+(int)((x3-x2)1.414/4),y3-(int)((y3-y2)1.414/4),x3,y3); break; case "橡皮擦" : Color pre = g.getColor(); //记录之前的颜色 ，用完再换回去 g.setColor( new JButton().getBackground()); g.fillRect(Math.min(x2,x3),Math.min(y2,y3),Math.abs(x3-x2),Math.abs(y3-y2)); g.setColor(pre); break; } } //递归KLine public void KLine(int x1 , int y1 , int x2 , int y2, int x){ if(Math.abs(x2-x1)<= 1 || Math.abs(y2-y1) <= 1 || x < 1){ g.drawLine(x1, y1, x2, y2); specialList.add(new Point(x1,y1)); return; } Random random = new Random(0); int ran = random.nextInt(x); int mid = ((y2+y1)/2-x+ran2); x = (int)(x0.618); KLine(x1, y1, (x1+x2)/2, mid,x); KLine((x1+x2)/2, mid, x2,y2,x); } //谢尔宾斯基地毯 public void Sierpinski(int x,int y,int w,int h){ if(w>0&&h>0){ g.fillRect(x+w/3,y+h/3,w/3,h/3); Sierpinski(x,y,w/3,h/3); Sierpinski(x+w/3,y,w/3,h/3); Sierpinski(x+2w/3,y,w/3,h/3); Sierpinski(x,y+h/3,w/3,h/3); Sierpinski(x+2w/3,y+h/3,w/3,h/3); Sierpinski(x,y+2h/3,w/3,h/3); Sierpinski(x+w/3,y+2h/3,w/3,h/3); Sierpinski(x+2w/3,y+2h/3,w/3,h/3); } } }较复杂一点的图形功能：签字笔、实时直线、三角形、多边形、改进多边形的实现签字笔：鼠标拖动时一直获取坐标，并将这个坐标与上一个坐标连接实时直线：鼠标按下时获取一个坐标，然后拖动时获取实时坐标连线，并将上一条线用一条背景色的直线覆盖。
三角形：鼠标点击时获取坐标①，再次点击获取坐标②，并将①②连接，再次点击获取坐标③，并将①③，②③连接。
多边形：第一次点击获取坐标①，此后每次点击获取坐标n，并连接坐标n和前一次点击获取的坐标，最后点击右键，连接坐标①和最后一次左键点击的坐标改进多边形：鼠标点击n次，然后用这个n个点作为顶点，画出一个多边形。
由于签字笔、三角形、多边形、改进多边形的实现比较复杂，所以我们将他们作为一个独立的类来写，我们的代码也更容易拓展和维护。
此时，我们的监听器的代码更新为三角形类

package drawBoard_test;import java.awt.;import java.awt.event.MouseEvent;public class Triangle { static int x1,y1,x2,y2,x3,y3; //对应三角形的三个点 static int num; //作为已经点了几个点的控制信号 public void drawTriangle(MouseEvent e , Graphics g){ if(num == 0){ x1 = e.getX(); y1 = e.getY(); num++; }else if(num == 1){ x2 = e.getX(); y2 = e.getY(); g.drawLine(x1,y1,x2,y2); num++; }else if(num == 2){ x3 = e.getX(); y3 = e.getY(); g.drawLine(x3,y3,x2,y2); g.drawLine(x3,y3,x1,y1); num=0; } }}多边形类

package drawBoard_test;import java.awt.;import java.awt.event.MouseEvent;public class Polygon { static int x1,y1,x2,y2,x3,y3; static int num; public void drawPolygon(MouseEvent e , Graphics g){ if(num == 0){ x1 = e.getX(); y1 = e.getY(); num++; }else if(num == 1){ x2 = e.getX(); y2 = e.getY(); g.drawLine(x1,y1,x2,y2); num++; }else if (num == 2){ if(e.getButton()==3){ g.drawLine(x1,y1,x2,y2); num=0; return; } x3 = e.getX(); y3 = e.getY(); g.drawLine(x3,y3,x2,y2); num++; }else if(num == 3){ if(e.getButton()==3){ g.drawLine(x1,y1,x3,y3); num=0; return; } x2 = e.getX(); y2 = e.getY(); g.drawLine(x3,y3,x2,y2); num--; } }}改进多边形类

package drawBoard_test;import java.awt.;import java.util.ArrayList;public class PolygonPro { //挑选x坐标最大的点作为基准点，计算其余点与基准点的正切值，根据正切值从大到小依次连接，得到一个多边形。
public void drawPolygonPro(ArrayList<Point> list, Graphics g){ if(list.size() == 0||list.size() == 1||list.size() == 2) return; int right = findRight(list); System.out.println(right); Point rightPoint = new Point(list.get(right).x, list.get(right).y); list.remove(right); double[] tan = new double[list.size()]; for (int i = 0; i < list.size(); i++) { tan[i] = ((double) rightPoint.y-list.get(i).y)/(rightPoint.x-list.get(i).x); } int pre; int cur = indexOfMax(tan); g.drawLine(list.get(cur).x,list.get(cur).y, rightPoint.x, rightPoint.y); tan[cur] = Integer.MIN_VALUE; for (int i = 0; i < tan.length-1; i++) { pre = cur; cur = indexOfMax(tan); g.drawLine(list.get(pre).x,list.get(pre).y, list.get(cur).x,list.get(cur).y); tan[cur] = Integer.MIN_VALUE; } g.drawLine(list.get(cur).x,list.get(cur).y, rightPoint.x, rightPoint.y); } private int findRight(ArrayList<Point> list) { int result = 0; for (int i = 1; i < list.size(); i++) { result = list.get(i).x>list.get(result).x?i:result; } return result ; } //返回数组中的最大值的下标 private int indexOfMax(double[] tan){ int v= 0 ; for(int i = 1 ; i < tan.length; i ++){ v = tan[i]>tan[v]?i:v; } return v; }}签字笔类

package drawBoard_test;import java.awt.;import java.awt.event.MouseEvent;public class Pen { public static int x1,y1,x2,y2; public static int state = 1; public void draw(MouseEvent e , Graphics g) { switch(state){ case 1 : x1 = e.getX(); y1 = e.getY(); state = 2; break; case 2 : x2 = e.getX(); y2 = e.getY(); g.drawLine(x2,y2,x1,y1); state = 3; break; case 3 : x1 = e.getX(); y1 = e.getY(); g.drawLine(x2,y2,x1,y1); state = 2; break; } }}实时直线类

package drawBoard_test;import javax.swing.;import java.awt.;import java.awt.event.MouseEvent;public class RealLine { public static int x1,y1,x2,y2,x3,y3; public void draw(MouseEvent e , Graphics g){ Color pre = g.getColor(); g.setColor( new JButton().getBackground()); if(x2 !=0 ){ g.drawLine(x2,y2,x1,y1); } g.setColor(pre); x3 = e.getX(); y3 = e.getY(); g.drawLine(x3,y3,x1,y1); x2=x3; y2=y3; }}

监听器DrawListener中的代码可以参考以下代码

ArrayList<Point> list = new ArrayList<>();//用于存放改进多边形的所有的顶点。
@Override public void mouseClicked(MouseEvent e) { if(shapeName == null) return; switch(shapeName){ case "三角形" : new Triangle().drawTriangle(e,g); break; case "多边形": new Polygon().drawPolygon(e,g); break; case "改进多边形": if(e.getButton()==3){ new PolygonPro().drawPolygonPro(list,g); list.clear(); break; }else{ Point point = new Point(e.getX(),e.getY()); list.add(point); break; } default: break; } } @Override public void mouseDragged(MouseEvent e) { if(shapeName == null) return; switch (shapeName){ case "实时直线": new RealLine().draw(e,g); break; case "签字笔": new Pen().draw(e,g); break; } } @Override public void mousePressed(MouseEvent e) { x2 = e.getX(); y2 = e.getY(); if(shapeName == null) return; switch (shapeName){ case "实时直线": RealLine.x1 = e.getX(); RealLine.y1 = e.getY(); RealLine.x2 = 0; break; } }第四步：实现重绘

到这里，我们的画图板的雏形已经完成了，但是也存在以下几个问题：

如何解决这些问题呢？

我们可以把每个的图形看作一个类，再用List集合把它们存储起来，然后重写主页面的paint方法（paint方法会在窗体初始化、拖动、改变尺寸、移出屏幕、最小化、最大化时调用），将List中的图形 在这个方法中遍历绘制出来。

@Override public void paint(Graphics g){ super.paint(g); for(Shapes shape : dl.shapeList){ shape.drawShape(g); } }

由于ArrayList只能存放一种对象，所以我们先创建一个父类shape,让shape的子类去重写drawShape方法。
在paint方法中遍历ArrayList集合时，每个对象调用自己独特的的drawShape方法，实现重绘。

package drawBoard_test2;import java.awt.Color;import java.awt.Graphics;public class Shapes { public String shapeName; // 图形的名称（要根据图形的名称，判断重绘的方法） public Color color; //画笔颜色(每个图形都有自己的颜色，重绘的时候图形的颜色也一样要保留) public void drawShape (Graphics g){ g.setColor(color); }}BasicShape类

package drawBoard_test2;import javax.swing.;import java.awt.;public class BasicShape extends Shapes { private int x1,y1,x2,y2; public BasicShape(String shapeName, Color color,int x1, int y1, int x2, int y2) { this.shapeName = shapeName; this.color = color; this.x1 = x1; this.y1 = y1; this.x2 = x2; this.y2 = y2; } @Override public void drawShape (Graphics g){ super.drawShape(g); switch (shapeName){ case "直线": g.setColor(color); g.drawLine(x1,y1,x2,y2); break; case "矩形": g.drawRect(Math.min(x1,x2),Math.min(y1,y2),Math.abs(x2-x1),Math.abs(y2-y1)); break; case "圆" : g.drawOval(Math.min(x1,x2),Math.min(y1,y2),Math.abs(x2-x1),Math.abs(y2-y1)); break; case "谢尔宾斯基地毯" : Sierpinski(g,Math.min(x1,x2),Math.min(y1,y2),Math.abs(x2-x1),Math.abs(y2-y1)); break; case "实心矩形" : g.fillRect(Math.min(x1,x2),Math.min(y1,y2),Math.abs(x2-x1),Math.abs(y2-y1)); break; case "实心圆" : g.fillOval(Math.min(x1,x2),Math.min(y1,y2),Math.abs(x2-x1),Math.abs(y2-y1)); break; case "等腰三角形" : g.drawLine(x1,y2,x2,y2); g.drawLine(x1,y2,(x1+x2)/2,y1); g.drawLine(x2,y2,(x1+x2)/2,y1); break; case "立方体" : g.drawRect(Math.min(x1,x2),Math.min(y1,y2),Math.abs(x2-x1),Math.abs(y2-y1)); g.drawLine(x1+(int)((x2-x1)1.414/4),y1-(int)((y2-y1)1.414/4),x1,y1); g.drawLine(x1+(int)((x2-x1)1.414/4),y1-(int)((y2-y1)1.414/4),x2+(int)((x2-x1)1.414/4),y1-(int)((y2-y1)1.414/4)); g.drawLine(x2,y1,x2+(int)((x2-x1)1.414/4),y1-(int)((y2-y1)1.414/4)); g.drawLine(x2+(int)((x2-x1)1.414/4),y2-(int)((y2-y1)1.414/4),x2+(int)((x2-x1)1.414/4),y1-(int)((y2-y1)1.414/4)); g.drawLine(x2+(int)((x2-x1)1.414/4),y2-(int)((y2-y1)1.414/4),x2,y2); break; case "橡皮擦" : Color pre = g.getColor(); //记录之前的颜色 ，用完再换回去 g.setColor( new JButton().getBackground()); g.fillRect(Math.min(x1,x2),Math.min(y1,y2),Math.abs(x2-x1),Math.abs(y2-y1)); g.setColor(pre); break; default: break; } } public void Sierpinski(Graphics g,int x,int y,int w,int h){ if(w>0&&h>0){ g.fillRect(x+w/3,y+h/3,w/3,h/3); Sierpinski(g,x,y,w/3,h/3); Sierpinski(g,x+w/3,y,w/3,h/3); Sierpinski(g,x+2w/3,y,w/3,h/3); Sierpinski(g,x,y+h/3,w/3,h/3); Sierpinski(g,x+2w/3,y+h/3,w/3,h/3); Sierpinski(g,x,y+2h/3,w/3,h/3); Sierpinski(g,x+w/3,y+2h/3,w/3,h/3); Sierpinski(g,x+2w/3,y+2h/3,w/3,h/3); } }}

当绘制出一个图形时，要将该图形加入到List集合中，所以监听器中的代码参考以下代码

@Override public void mouseReleased(MouseEvent e) { x3 = e.getX(); y3 = e.getY(); if(shapeName == null) return; switch(shapeName){ case "直线": case "矩形": case "圆" : case "谢尔宾斯基地毯": case "实心矩形" : case "实心圆" : case "等腰三角形" : case "立方体" : case "橡皮擦" : BasicShape basicShape = new BasicShape(shapeName, new Color(color.getRGB()), x2, y2, x3, y3); basicShape.drawShape(g); shapeList.add(basicShape); break; } }

至此，我们就完成了简单图形的重绘。
我们还剩签字笔、实时直线、递归KLine、三角形、多边形、改进多边形等图形需要绘制。

这些图形有什么共同的属性可以提取吗？他们的共同点是坐标点都比较多，数量不能确定，我们可以设置一个List属性，把每个图形的点都存在这个集合里， 然后重绘时，调用drawShape方法把集合里的点取出来，再绘制出来。

说做就做，我们创建一个specialShape类，主要属性为一个ArrayList集合，其余属性根据绘制的需要来定。

package drawBoard_test2;import java.awt.;import java.util.ArrayList;public class SpecialShape extends Shapes { public ArrayList<Point> specialList = new ArrayList<>(); private Point first; private Point pre; private Point cur; public SpecialShape(String shapeName, Color color, ArrayList<Point> specialList) { this.shapeName = shapeName; this.color = color; for (Point p : specialList) { this.specialList.add(p); } } @Override public void drawShape(Graphics g) { super.drawShape(g); switch (shapeName) { case "三角形": case "多边形": case "改进多边形": if (specialList.isEmpty()) break; int i = 0; first = specialList.get(i++); cur = first; while (i < specialList.size()) { pre = cur; cur = specialList.get(i++); g.drawLine(pre.x, pre.y, cur.x, cur.y); } g.drawLine(first.x, first.y, cur.x, cur.y); break; case "签字笔": case "递归KLine": case "实时直线": if (specialList.isEmpty()) break; int j = 0; while (j < specialList.size()-1) { g.drawLine(specialList.get(j).x, specialList.get(j).y, specialList.get(j+1).x, specialList.get(++j).y); } break; } }}

接下来，我们需要做的就是将每个图形的点按顺序添加进specialList中，点都收集完之后，将一个新建的specialShape对象放入我们的图形集合ShapeList中，所以我们修改每个图形中的代码：

/ @param specialList 三角形的顶点存入SpecialShape的集合，存入的顺序应该为顺次连接的点的顺序 @param shapeList 重绘时使用的图形集合 / public void drawTriangle(MouseEvent e , Graphics g, ArrayList<Point> specialList, Color color, ArrayList<Shapes> shapeList){ if(num == 0){ specialList.clear(); x1 = e.getX(); y1 = e.getY(); num++; specialList.add(new Point(x1,y1)); }else if(num == 1){ x2 = e.getX(); y2 = e.getY(); g.drawLine(x1,y1,x2,y2); num++; specialList.add(new Point(x2,y2)); }else if(num == 2){ x3 = e.getX(); y3 = e.getY(); g.drawLine(x3,y3,x2,y2); g.drawLine(x3,y3,x1,y1); num=0; specialList.add(new Point(x3,y3)); SpecialShape specialShape = new SpecialShape("三角形", new Color(color.getRGB()), specialList); shapeList.add(specialShape); } }

相应的监听器中的代码，做出相应的修改，

/ 创建一个specialList集合用来存放每个图形的点，将它传入图形的绘制方法中， 当收集到所有的点时，将以集合作为成员变量创建的specialShape对象存入shape集合中。
/ArrayList<Point> specialList = new ArrayList<>();case "三角形" : new Triangle().drawTriangle(e,g,specialList,color,shapeList); break;

其他的类的方法也是如出一辙，大家在写出来之后，可以和鄙人的代码进行比对。
这里给出其余代码：

public class Polygon { static int x1,y1,x2,y2,x3,y3; static int num; / @param e @param g @param specialList 多边形的顶点存入SpecialShape的集合，存入的顺序应该为顺次连接的点的顺序 @param color @param shapeList 重绘时使用的图形集合 / public void drawPolygon(MouseEvent e , Graphics g, ArrayList<Point> specialList, Color color, ArrayList<Shapes> shapeList){ if(num == 0){ //第一个点 x1 = e.getX(); y1 = e.getY(); num++; specialList.clear(); specialList.add(new Point(x1,y1)); }else if(num == 1){ // x2 = e.getX(); y2 = e.getY(); g.drawLine(x1,y1,x2,y2); num++; specialList.add(new Point(x2,y2)); }else if (num == 2){ if(e.getButton()==3){ //右键结束时，所有的点已经确定，我们新建一个specialShape对象存入specialList集合中。
g.drawLine(x1,y1,x2,y2); num=0; SpecialShape specialShape = new SpecialShape("多边形", new Color(color.getRGB()), specialList); shapeList.add(specialShape); specialList.clear(); return; } x3 = e.getX(); y3 = e.getY(); g.drawLine(x3,y3,x2,y2); specialList.add(new Point(x3,y3)); num++; }else if(num == 3){ if(e.getButton()==3){ g.drawLine(x1,y1,x3,y3); num=0; SpecialShape specialShape = new SpecialShape("多边形", new Color(color.getRGB()), specialList); shapeList.add(specialShape); specialList.clear(); return; } x2 = e.getX(); y2 = e.getY(); g.drawLine(x3,y3,x2,y2); specialList.add(new Point(x2,y2)); num--; } }}/ 多边形对应监听器中的方法 mouseClicked方法 /case "多边形": new Polygon().drawPolygon(e,g,specialList,color,shapeList); break;改进多边形

/ 改进多边形类的draw方法 @param ArrayList<Point> list 多边形顶点的集合，顺序为鼠标绘制时 点击的顺序 @param ArrayList<Point> specialList 多边形的顶点存入SpecialShape的集合，存入的顺序应该为顺次连接的点的顺序 @param ArrayList<Shapes> shapeList 重绘时使用的图形集合 /public void drawPolygonPro(ArrayList<Point> list, Graphics g, ArrayList<Point> specialList, Color color, ArrayList<Shapes> shapeList){ if(list.size() == 0||list.size() == 1||list.size() == 2) return; int right = findRight(list); System.out.println(right); Point rightPoint = new Point(list.get(right).x, list.get(right).y); specialList.add(rightPoint); list.remove(right); double[] tan = new double[list.size()]; for (int i = 0; i < list.size(); i++) { tan[i] = ((double) rightPoint.y-list.get(i).y)/(rightPoint.x-list.get(i).x); } int pre; int cur = indexOfMax(tan); specialList.add(list.get(cur)); g.drawLine(list.get(cur).x,list.get(cur).y, rightPoint.x, rightPoint.y); tan[cur] = Integer.MIN_VALUE; for (int i = 0; i < tan.length-1; i++) { pre = cur; cur = indexOfMax(tan); specialList.add(list.get(cur)); g.drawLine(list.get(pre).x,list.get(pre).y, list.get(cur).x,list.get(cur).y); tan[cur] = Integer.MIN_VALUE; } g.drawLine(list.get(cur).x,list.get(cur).y, rightPoint.x, rightPoint.y); }/ 改进多边形对应监听器中的方法 / case "改进多边形": if(e.getButton()==3){ new PolygonPro().drawPolygonPro(list,g,specialList,color,shapeList); SpecialShape specialShape = new SpecialShape("改进多边形",color,specialList); shapeList.add(specialShape); specialList.clear(); list.clear(); break; }else{ Point point = new Point(e.getX(),e.getY()); list.add(point); break; }递归KLine曲线

case "递归KLine": KLine(x2,y2,x3,y3,Math.abs(y3-y2)); specialList.add(new Point(x3,y3)); SpecialShape specialShape = new SpecialShape(shapeName, new Color(color.getRGB()), specialList); shapeList.add(specialShape); specialList.clear(); break;/ 递归Kline实现方法 /public void KLine(int x1 , int y1 , int x2 , int y2, int x){ if(Math.abs(x2-x1)<= 1 || Math.abs(y2-y1) <= 1 || x < 1){ g.drawLine(x1, y1, x2, y2); specialList.add(new Point(x1,y1)); return; } Random random = new Random(0); int ran = random.nextInt(x); int mid = ((y2+y1)/2-x+ran2); x = (int)(x0.618); KLine(x1, y1, (x1+x2)/2, mid,x); KLine((x1+x2)/2, mid, x2,y2,x); }签字笔类

/ 签字笔类的代码修改 /public void draw(MouseEvent e , Graphics g, ArrayList<Point> specialList, Color color, ArrayList<Shapes> shapeList) { switch(state){ case 1 : x1 = e.getX(); y1 = e.getY(); specialList.add(new Point(x1,y1)); state = 2; break; case 2 : x2 = e.getX(); y2 = e.getY(); specialList.add(new Point(x2,y2)); g.drawLine(x2,y2,x1,y1); state = 3; break; case 3 : x1 = e.getX(); y1 = e.getY(); specialList.add(new Point(x1,y1)); g.drawLine(x2,y2,x1,y1); state = 2; break; } }/ mouseDragged /case "签字笔": new Pen().draw(e,g,specialList,color,shapeList); break;/ mouseReleased /case "签字笔" : SpecialShape specialShape2 = new SpecialShape(shapeName, new Color(color.getRGB()), specialList); shapeList.add(specialShape2); specialList.clear(); Pen.state=1; break;实时直线类

public class RealLine { public static int x1,y1,x2,y2,x3,y3; public void draw(MouseEvent e , Graphics g, ArrayList<Point> specialList, Color color, ArrayList<Shapes> shapeList){ Color pre = g.getColor(); g.setColor( new JButton().getBackground()); if(x2 !=0 ){ g.drawLine(x2,y2,x1,y1); } g.setColor(pre); x3 = e.getX(); y3 = e.getY(); g.drawLine(x3,y3,x1,y1); x2=x3; y2=y3; }}/ mousePressed / case "实时直线": specialList.add(new Point(x2,y2)); RealLine.x1 = e.getX(); RealLine.y1 = e.getY(); RealLine.x2 = 0; break;/ mouseReleased / case "实时直线": specialList.add(new Point(x3,y3)); SpecialShape specialShape3 = new SpecialShape(shapeName, new Color(color.getRGB()), specialList); shapeList.add(specialShape3); specialList.clear(); break;

接下来，我们发现，图形确实可以实现重绘了，但是每次调用paint方法时，绘制的速度总是很慢，尤其是重绘谢尔宾斯基地毯时，是肉眼可见的慢，这是什么原因导致的呢？

我们知道，绘制的内容要显示到屏幕上，需要把 内存数据 提交 给显卡 ，通过显卡再渲染计算 显示到屏幕。
计算机的计算速度是非常快的，但是我们每计算出几个像素点，就直接输出到屏幕上，以至于 要画的次数很多，这导致了计算机IO 与 计算不匹配。

我们如何解决这种问题？

计算快，但IO很慢，我们就让计算机先计算好，再输出到屏幕上。
我们使用 缓存（BufferedImage类），把下一帧需要显示的画面上所有的图形内容都计算好并存起来，然后再一次性绘出 。

BufferedImage 缓存图片 属性：宽、高 格式为像素存储格式 使用Graphics类作为画笔

public void paint(Graphics g){ super.paint(g); BufferedImage bufferedImage = new BufferedImage(1000,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg = bufferedImage.getGraphics(); for(Shapes shape : dl.shapeList){ shape.drawShape(buffg); } g.drawImage(bufferedImage,0,0,null); }

此时再来试试重绘的功能，是不是感觉很神奇。

public class RealLine { public static int x1,y1,x2,y2,x3,y3; public void draw(MouseEvent e , Graphics g, ArrayList<Point> specialList, Color color, ArrayList<Shapes> shapeList){ Color pre = g.getColor(); g.setColor( new JButton().getBackground()); if(x2 !=0 ){ g.drawLine(x2,y2,x1,y1); } g.setColor(pre); x3 = e.getX(); y3 = e.getY(); g.drawLine(x3,y3,x1,y1); x2=x3; y2=y3; BufferedImage bufferedImage = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffs = bufferedImage.getGraphics(); for(Shapes shape : shapeList){ shape.drawShape(buffs); } g.drawImage(bufferedImage,0,0,null); }}第五步：实现撤回,清空功能我们已经实现了重绘功能，撤回就很简单了，我们只需要把shapeList中最近添加进去的图形删掉，然后重绘就可以了。
清空就是把shapeList中所有的图形删掉，然后重绘。
代码实现：

/ actionPerformed /switch(shapeName) { case "撤回": if (!shapeList.isEmpty()) { shapeList.remove(shapeList.size() - 1); drawUI.paint(g); } break; case "清空" : shapeList.clear(); drawJPanel.paint(g); break;}/ 然后我们需要涉及到传值的问题，我们在监听器页面添加一个drawUI对象成员，然后把DrawUI类中的main函数中的drawUI对象传给监听器 /第六步：打开与保存操作两点需要注意：①为了加快打开图片的速度，我们把图片需要显示的画面都画在BufferedImage中，然后再一次性绘出。
②我们绘制的图形可以实现撤回功能，那么我们打开的图片能不能也实现撤回功能呢？当然可以，我们只需要把打开的图片也存入ShapeList集合中，所以我们创建一个ImageShape类（继承Shape类），用来存储图片。
ImageShape类

package drawBoard_test2;import java.awt.;import java.awt.image.BufferedImage;public class ImageShape extends Shapes { BufferedImage bufferedImage; @Override //重绘方法 public void drawShape(Graphics g){ g.drawImage(bufferedImage,0,0,null); } //封装 BufferedImage的set方法 public void setBufferedImage(BufferedImage bufferedImage) { this.bufferedImage = bufferedImage; }}打开

String fileName;/ 打开操作步骤：将图片转化为二维数组，遍历每个点在画图板上画出 JFileChooser 文件选择器 FileNameExtensionFilter 文件过滤器，构造方法的参数JPG & GIF Images为筛选文件的选项， "jpg", "gif"为筛选文件的类型 / //actionPerformed case "打开" : JFileChooser chooser = new JFileChooser(); FileNameExtensionFilter filter = new FileNameExtensionFilter ( "JPG & GIF Images", "jpg", "gif"); chooser.setFileFilter(filter); int returnVal = chooser.showOpenDialog(null); if(returnVal == JFileChooser.APPROVE_OPTION) { //JFileChooser.APPROVE_OPTION 批准选项 System.out.println("You chose to open this file: " + chooser.getSelectedFile().getPath()); fileName = chooser.getSelectedFile().getPath(); //获取文件的本地路径 } BufferedImage bufferedImage = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg = bufferedImage.getGraphics(); int[][] img = getImagePixel(fileName); drawImage(buffg,img); ImageShape imageShape = new ImageShape(); imageShape.setBufferedImage(bufferedImage); g.drawImage(bufferedImage,0,0,null); shapeList.add(imageShape); break;/ drawImage将图形画在画图板上 /public void drawImage(Graphics g ,int[][] img){ for (int i = 0; i < img.length; i++) { for (int j = 0; j < img[i].length; j++) { Color c = new Color(img[i][j]); g.setColor(c); g.drawOval(i , j, 1, 1); } }}/ getImagePixel 返回图片的二维数组 /public static int[][] getImagePixel(String filePath) { File file = new File(filePath); //filePath为文件路径 BufferedImage bi = null; try{ bi = ImageIO.read(file); } catch (Exception e) { e.printStackTrace(); } int w = bi.getWidth(); int h = bi.getHeight(); int[][] imIndex = new int[w][h]; for (int i = 0; i < w; i++) { for (int j = 0; j < h; j++) { int pixel = bi.getRGB(i,j); imIndex[i][j] = pixel; } } return imIndex;}}return imIndex;}保存

/ 保存为的文件名的后缀应为png /case "保存": JFileChooser chooser2 = new JFileChooser(); FileNameExtensionFilter filter2 = new FileNameExtensionFilter( "JPG & GIF Images", "jpg","gif" ); chooser2.setFileFilter(filter2); int returnVal2 = chooser2.showSaveDialog(null); if(returnVal2 == JFileChooser.APPROVE_OPTION){ System.out.println("You choose to save this file:" + chooser2.getSelectedFile().getPath()); } //把所有的图形重绘到bufferedImage上，再把bufferedImage存入图片文件中 BufferedImage bufferedImage2 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg2 = bufferedImage2.getGraphics(); for(Shape shape : shapeList ){ shape.drawShape(buffg2); } File file2 = new File(chooser2.getSelectedFile().getPath()); try { ImageIO.write(bufferedImage2,"png",file2); } catch (IOException ex) { ex.printStackTrace(); } break;第七步：美化界面，并添加图片处理功能按钮

此时我们的画布、图形按钮、颜色按钮放在一起，如果我们后面再加入图形处理按钮，界面将会变得很不整洁，所以我们使用边框布局来将窗体分区管理。

我们要将画板从整个窗体改成了一个JPanel，但是我们的重绘功能还需要重写过的paint方法，所以我们新建一个DrawJPanel类来继承JPanel类，去重写paint方法。

public class DrawUI extends JFrame { DrawListener dl = new DrawListener(); String[] strs = {"直线","签字笔","实时直线", "谢尔宾斯基地毯","递归KLine","矩形", "圆", "实心矩形", "实心圆", "等腰三角形", "三角形", "多边形", "改进多边形","立方体", "橡皮擦", "撤回", "保存", "打开"}; Color[] color = {Color.red,Color.yellow,Color.black,Color.blue}; public void addShapeButton(JComponent component){ for(String str : strs){ JButton btn = new JButton(str); btn.addActionListener(dl); component.add(btn); } } public void addColorButton(JComponent component){ Dimension dim = new Dimension(30,30); for(Color c : color){ JButton btn = new JButton(); btn.setBackground(c); btn.setPreferredSize(dim); btn.addActionListener(dl); component.add(btn); } Dimension dim2 = new Dimension(95,30); JButton btn = new JButton("选择颜色..."); btn.setPreferredSize(dim2); btn.addActionListener(dl); component.add(btn); } public void addBeautyButton(JComponent component){ String[] str = {"原图","马赛克","灰度","二值化","背景替换","油画","图片融合","磨皮"}; for(String s : str){ JButton btn = new JButton(s); btn.addActionListener(dl); component.add(btn); } } public void initUI(){ JFrame jf = new JFrame("画图板"); jf.setTitle("画图板"); jf.setLayout(new BorderLayout()); jf.setSize(1000,800); jf.setLocationRelativeTo(null); jf.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); //菜单栏 JMenuBar jMenuBar = new JMenuBar(); JMenu jMenu = new JMenu("菜单",true); String[] Menu = {"撤回","打开","保存","清空"}; for(String s : Menu){ JMenuItem jMenuItem = new JMenuItem(s); jMenu.add(jMenuItem); jMenuItem.addActionListener(dl); } jMenuBar.add(jMenu); jf.setJMenuBar(jMenuBar); JPanel shapeChooserPanel = new JPanel(); DrawJPanel drawPanel = new DrawJPanel(); JPanel ChooserPanel = new JPanel(); JPanel ColorChooserPanel = new JPanel(); ChooserPanel.setLayout(new BorderLayout()); dl.drawJPanel = drawPanel; JPanel RightPanel = new JPanel(); //大小 Dimension dim = new Dimension(150,80); shapeChooserPanel.setPreferredSize(dim); ChooserPanel.setPreferredSize(dim); Dimension dim2 = new Dimension(150,330); RightPanel.setPreferredSize(dim2); ColorChooserPanel.setPreferredSize(dim2); ChooserPanel.setPreferredSize(dim2); //背景颜色 Color color1 = new Color(-3355444); shapeChooserPanel.setBackground(color1); Color color2 = new Color(-6710887); ColorChooserPanel.setBackground(color2); ChooserPanel.setBackground(color2); RightPanel.setBackground(color1); //方位 jf.add(shapeChooserPanel,BorderLayout.NORTH); jf.add(ChooserPanel,BorderLayout.EAST); jf.add(drawPanel,BorderLayout.CENTER); ChooserPanel.add(RightPanel,BorderLayout.SOUTH); ChooserPanel.add(ColorChooserPanel,BorderLayout.NORTH); //添加按钮 addShapeButton(shapeChooserPanel); addColorButton(ColorChooserPanel); addBeautyButton(RightPanel); jf.setVisible(true); Graphics g = drawPanel.getGraphics (); drawPanel.addMouseMotionListener(dl); drawPanel.addMouseListener(dl); drawPanel.setDl(dl); dl.setG(g); } public static void main(String[] args) { new DrawUI().initUI(); }}选择颜色

/ 监听器中的actionPerformed方法 /if(btn_action.equals("选择颜色...")){ color = JColorChooser.showDialog(drawJPanel, "选择颜色", Color.red); System.out.println(color.getRGB()); g.setColor(color); return; }第八步：图像处理功能深入理解color类：rgb数字构成颜色 Color c = new Color(200,50,100);其值在0~255之间。
rgb的三个数字分别对应red,green,blueint数字构成颜色 Color c = new Color(-3355444),其值为int类型。
马赛克

/ 马赛克 把像素点放大 /case "马赛克": BufferedImage bufferedImage3 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg3 = bufferedImage3.getGraphics(); int[][] img3 = getImagePixel(fileName); drawImage_MSK(buffg3,img3); ImageShape imageShape3 = new ImageShape(); imageShape3.setBufferedImage(bufferedImage3); g.drawImage(bufferedImage3,0,0,null); shapeList.add(imageShape3); break;public void drawImage_MSK(Graphics g ,int[][] img){ int w = (drawJPanel.getWidth()- img.length)/2; int h = (drawJPanel.getHeight()- img[0].length)/2; for (int i = 0; i < img.length; i+=8) { for (int j = 0; j < img[i].length; j+=8) { Color c = new Color(img[i][j]); g.setColor(c); g.fillRect(i+w , j+h, 8, 8); } }} 灰度

/ 灰度图像 rgb三个分量都相同，一般可以取其平均值 这里使用的是灰度值的浮点法计算，读者可以参考该网址，尝试一下Gamma校正算法 https://baike.baidu.com/item/%E7%81%B0%E5%BA%A6%E5%80%BC/10259111?fr=aladdin /case "灰度": BufferedImage bufferedImage6 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg6 = bufferedImage6.getGraphics(); int[][] img6 = getImagePixel(fileName); drawImage_gray(buffg6,img6); ImageShape imageShape6 = new ImageShape(); imageShape6.setBufferedImage(bufferedImage6); g.drawImage(bufferedImage6,0,0,null); shapeList.add(imageShape6); break;public void drawImage_gray(Graphics g ,int[][] img){ int w = (drawJPanel.getWidth()- img.length)/2; int h = (drawJPanel.getHeight()- img[0].length)/2; for (int i = 0; i < img.length; i++) { for (int j = 0; j < img[i].length; j++) { int value = img[i][j]; int red = (value>>16) & 0xff; int green = (value>>8) & 0xff; int blue = value & 0xff; int gray = (int) (0.3 red + 0.59 green + 0.11 blue); Color c = new Color(gray,gray,gray); g.setColor(c); g.fillRect(i+w , j+h, 1, 1); } }}二值化

/ 二值图像 指仅有黑白两色的图像（大于某值的画白，小于某值的画黑） /case "二值化": BufferedImage bufferedImage7 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg7 = bufferedImage7.getGraphics(); int[][] img7 = getImagePixel(fileName); drawImage_binary(buffg7,img7); ImageShape imageShape7 = new ImageShape(); imageShape7.setBufferedImage(bufferedImage7); g.drawImage(bufferedImage7,0,0,null); shapeList.add(imageShape7); break;public void drawImage_binary(Graphics g ,int[][] img){ int w = (drawJPanel.getWidth()- img.length)/2; int h = (drawJPanel.getHeight()- img[0].length)/2; for (int i = 0; i < img.length; i++) { for (int j = 0; j < img[i].length; j++) { int value = img[i][j]; int red = (value>>16) & 0xff; int green = (value>>8) & 0xff; int blue = value & 0xff; int gray = (int) (0.3 red + 0.59 green + 0.11 blue); if(gray < 150){ g.setColor(Color.black); }else { g.setColor(Color.white); } g.fillRect(i+w , j+h, 1, 1); } }}背景替换

/ 背景替换图像 当图片的背景为白色时，我们将大于某一值的像素点，替换为另一张图片的像素点 /case "背景替换": BufferedImage bufferedImage8 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg8 = bufferedImage8.getGraphics(); int[][] img8 = getImagePixel(fileName); int[][] background = getImagePixel("C:\\Users\\13630\\Desktop\\背景.jpg"); drawImage_replaceBackground(buffg8,img8,background); ImageShape imageShape8 = new ImageShape(); imageShape8.setBufferedImage(bufferedImage8); g.drawImage(bufferedImage8,0,0,null); shapeList.add(imageShape8); break;public void drawImage_replaceBackground(Graphics g ,int[][] img,int[][] background){ int w = (drawJPanel.getWidth()- img.length)/2; int h = (drawJPanel.getHeight()- img[0].length)/2; for (int i = 0; i < img.length; i++) { for (int j = 0; j < img[i].length; j++) { int value = img[i][j]; int red = (value>>16) & 0xff; int green = (value>>8) & 0xff; int blue = value & 0xff; int gray = (int) (0.3 red + 0.59 green + 0.11 blue); if(gray > 240&&i< background.length&&j<background[i].length){ g.setColor(new Color(background[i][j])); }else { g.setColor(new Color(img[i][j])); } g.fillRect(i+w , j+h, 1, 1); } }}油画

/ 原理与马赛克类似，不同的是油画效果要填充随机大小的色块 /case "油画": BufferedImage bufferedImage9 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg9 = bufferedImage9.getGraphics(); int[][] img9 = getImagePixel(fileName); drawImage_OilPainting(buffg9,img9); ImageShape imageShape9 = new ImageShape(); imageShape9.setBufferedImage(bufferedImage9); g.drawImage(bufferedImage9,0,0,null); shapeList.add(imageShape9); break;public void drawImage_OilPainting(Graphics g ,int[][] img){ int w = (drawJPanel.getWidth()- img.length)/2; int h = (drawJPanel.getHeight()- img[0].length)/2; for (int i = 0; i < img.length; i+=5) { for (int j = 0; j < img[i].length; j+=5) { g.setColor(new Color(img[i][j])); Random random = new Random(); int ran = random.nextInt(20)+5; g.fillOval(i+w , j+h, ran, ran); } }}图片融合

/ 需要两张照片 融合后图片像素点的颜色 为融合前的两张照片像素点颜色以不同比例融合 /case "图片融合": BufferedImage bufferedImage10 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg10 = bufferedImage10.getGraphics(); int[][] img10 = getImagePixel(fileName); int[][] background2 = getImagePixel("C:\\Users\\13630\\Desktop\\背景.jpg"); drawImage_fusion(buffg10,img10,background2); ImageShape imageShape10 = new ImageShape(); imageShape10.setBufferedImage(bufferedImage10); g.drawImage(bufferedImage10,0,0,null); shapeList.add(imageShape10); break;public void drawImage_fusion(Graphics g ,int[][] img,int[][] background){ int w = Math.min(img.length, background.length); int h = Math.min(img[0].length, background[0].length); for (int i = 0; i < w; i++) { for (int j = 0; j < h; j++) { Color ca = new Color(img[i][j]); Color cb = new Color(background[i][j]); int red = (int) (ca.getRed()0.7+ cb.getRed()0.3); int green = (int)(ca.getGreen() 0.3+cb.getGreen()0.7); int blue = (int)(ca.getBlue()0.3+ cb.getBlue()0.7); Color c = new Color(red,green,blue); g.setColor(c); g.fillRect(i , j, 1, 1); } }}原图

case "原图": BufferedImage bufferedImage5 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg5 = bufferedImage5.getGraphics(); int[][] img5 = getImagePixel(fileName); drawImage(buffg5,img5); ImageShape imageShape5 = new ImageShape(); imageShape5.setBufferedImage(bufferedImage5); g.drawImage(bufferedImage5,0,0,null); shapeList.add(imageShape5); break; //画在画图区域的中央public void drawImage(Graphics g ,int[][] img){ int w = (drawPanel.getWidth()- img.length)/2; int h = (drawPanel.getHeight()- img[0].length)/2; for (int i = 0; i < img.length; i++) { for (int j = 0; j < img[i].length; j++) { Color c = new Color(img[i][j]); g.setColor(c); g.drawOval(w+i , h+j, 1, 1); } }}磨皮磨皮是为了把有瑕疵的地方覆盖住，所以我们用一种和周围相同颜色的粗画笔去覆盖图片上的瑕疵。
我们实时获取鼠标所在位置的颜色，然后画出与此颜色相同的颜色，实现方式与签字笔相同磨皮类

package drawBoard_test2;import java.awt.;import java.awt.event.MouseEvent;import java.util.ArrayList;public class SkinGrinding { public static int x1,y1,x2,y2; public static int state = 1; public void draw(MouseEvent e , Graphics2D g, ArrayList<Point> specialList, int[][] img, ArrayList<Shapes> shapeList,int w,int h) { switch(state){ case 1 : x1 = e.getX(); y1 = e.getY(); specialList.add(new Point(x1,y1)); state = 2; break; case 2 : x2 = e.getX(); y2 = e.getY(); g.setColor(new Color(img[x2-w][y2-h])); specialList.add(new Point(x2,y2)); g.drawLine(x2,y2,x1,y1); state = 3; break; case 3 : x1 = e.getX(); y1 = e.getY(); specialList.add(new Point(x1,y1)); g.setColor(new Color(img[x1-w][y1-h])); g.drawLine(x2,y2,x1,y1); state = 2; break; } }}

监听器中添加的代码

监听器中加一个img11[][],用来存放当然处理的照片的像素点/ actionPerformed /case "磨皮": img11 = getImagePixel(fileName); break;/ mousePressed /case "磨皮": g2D = (Graphics2D)g; g2D.setStroke (new BasicStroke (3)); specialList.add(new Point(x2,y2)); break;/ mouseReleased /case "磨皮": SpecialShape specialShape4 = new SpecialShape(shapeName, new Color(color.getRGB()), specialList); shapeList.add(specialShape4); specialList.clear(); SkinGrinding.state=1; break;/ mouseDragged /case "磨皮": int w = (drawJPanel.getWidth()- img11.length)/2; int h = (drawJPanel.getHeight()- img11[0].length)/2; new SkinGrinding().draw(e,g2D,specialList,img11,shapeList,w,h); break;第九步：”更多操作“界面的绘制先看效果图：22.cnblogs.com/blog/2555328/202204/2555328-20220414151122093-1753505041.png)

package drawBoard_test2;import javax.swing.;import java.awt.;import java.util.ArrayList;public class ButtonUI extends JFrame { public static DrawUI drawUI; public void init (){ JFrame jf = new JFrame(); jf.setTitle("更多操作"); jf.setSize(380,500); jf.setLocationRelativeTo(drawUI); jf.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); jf.setLayout(new FlowLayout()); addJSlider(jf); addButton(jf); addJSlider2(jf); jf.setVisible(true); } public void addButton (JFrame component){ String[] strings = {"放大130%","缩小50%","向左旋转","向右旋转"}; for(String s : strings){ JButton btn = new JButton(s); component.add(btn); btn.addActionListener(DrawUI.dl); } } public void addJSlider(JFrame component){ JLabel jl = new JLabel("缩放比例（%）："); JSlider jSlider = new JSlider(0,200); jSlider.setToolTipText("缩放比例"); jSlider.setMajorTickSpacing(30); jSlider.setMinorTickSpacing(10); jSlider.setPaintLabels(true); jSlider.setPaintTicks(true); jSlider.addChangeListener(DrawUI.dl); component.add(jl); component.add(jSlider); } public void addJSlider2(JFrame component){ JLabel jl1 = new JLabel("红色亮度（%）："); JSlider jSlider1 = new JSlider(0,0,200,100); jSlider1.setToolTipText("红色"); jSlider1.setMajorTickSpacing(30); jSlider1.setMinorTickSpacing(10); jSlider1.setPaintLabels(true); jSlider1.setPaintTicks(true); jSlider1.addChangeListener(DrawUI.dl); component.add(jl1); component.add(jSlider1); JLabel jl2 = new JLabel("绿色亮度（%）："); JSlider jSlider2 = new JSlider(0,0,200,100); jSlider2.setToolTipText("绿色"); jSlider2.setMajorTickSpacing(30); jSlider2.setMinorTickSpacing(10); jSlider2.setPaintLabels(true); jSlider2.setPaintTicks(true); jSlider2.addChangeListener(DrawUI.dl); component.add(jl2); component.add(jSlider2); JLabel jl3 = new JLabel("蓝色亮度（%）："); JSlider jSlider3 = new JSlider(0,0,200,100); jSlider3.setToolTipText("蓝色"); jSlider3.setMajorTickSpacing(30); jSlider3.setMinorTickSpacing(10); jSlider3.setPaintLabels(true); jSlider3.setPaintTicks(true); jSlider3.addChangeListener(DrawUI.dl); component.add(jl3); component.add(jSlider3); //确认和取消按钮； JButton btn1 = new JButton("确认"); btn1.addActionListener(DrawUI.dl); component.add(btn1); JButton btn2 = new JButton("取消"); btn2.addActionListener(DrawUI.dl); component.add(btn2); } public static void main(String[] args) { new ButtonUI().init(); }}第十步：放大、缩小功能放大缩小的方法：获取原图形像素点的二维数组，用最邻近元法计算出待求像素点，再利用BufferedImage作为缓冲，画到画布上。
最邻近元法参考这个网站：图像插值_百度百科

@Overridepublic void stateChanged(ChangeEvent e) { JSlider jSlider = (JSlider)e.getSource(); String s = jSlider.getToolTipText(); switch (s){ case "缩放比例": multiple = jSlider.getValue(); int[][] img = getImagePixel(fileName); BufferedImage bufferedImage = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg = bufferedImage.getGraphics(); drawImage_multiple(buffg,img); g.drawImage(bufferedImage,0,0,null); break; }}public void drawImage_multiple(Graphics g , int[][] img){ int w = (int)((drawJPanel.getWidth()- img.length1.0(multiple)/100)/2); int h = (int)((drawJPanel.getHeight()- img[0].length1.0multiple/100)/2); for (int i = 0; i < img.length; i++) { for (int j = 0; j < img[i].length; j++) { g.setColor(new Color(img[i][j])); for (int k = (int)(i1.0multiple/100); k < (int)((i+1)1.0multiple/100) ; k++) { for (int l = (int)(1.0jmultiple/100); l < (int)((j+1)1.0multiple/100); l++) { g.drawRect(k+w,l+h,1,1); } } } }}第十一步：图片的颜色调整要实现的功能：通过滑动条，分别用来改变红绿蓝三种颜色的数值大小，来达到调整整个图片颜色的效果实现途径：自己编写一个存储图片的动态数组类，将red,green,blue分别用一个矩阵数组存储起来，

package drawBoard_test2;import javax.swing.text.Segment;import java.awt.image.BufferedImage;/ 这是一个用来存储图片的动态数组类 /可以实现数组自动扩容 存储的图片对象类型是： BufferedImage 目前实现了： add方法 get方法 remove方法 size方法 /public class ImageArray { private BufferedImage[] imgArray = {}; / 数组默认初始化容量 / private static final int defaultLength = 10; private int size; / 数组当前的空间容量 / private int length; // 每张存入进来图片的三 通道矩阵数组 public ColorArray[] redArray = {}; public ColorArray[] greenArray = {}; public ColorArray[] blueArray = {}; public int getSize(){ return size; } //放大或缩小redArray的数值 public int[][] multiple(int multiple , ColorArray colorArray){ int w = colorArray.array.length; int h = colorArray.array[0].length; int[][] res = new int[w][h]; for (int i = 0; i < w; i++) { for (int j = 0; j < h; j++) { res[i][j] = Math.min(255,(int)(colorArray.array[i][j]1.0multiple/100)); } } return res; } / 图片动态数组的初始化构造方法 / public ImageArray(int initSize){ if(initSize < defaultLength){ length = defaultLength; imgArray = new BufferedImage[length]; redArray = new ColorArray[length]; greenArray = new ColorArray[length]; blueArray = new ColorArray[length]; size = 0; }else{ length = initSize; imgArray = new BufferedImage[length]; redArray = new ColorArray[length]; greenArray = new ColorArray[length]; blueArray = new ColorArray[length]; size = 0; } } public void add(BufferedImage img){ if(size >= length){ int oldlength = length; length = oldlength + oldlength>>1; BufferedImage[] newArray = new BufferedImage[length]; for (int i = 0; i < oldlength; i++) { newArray[i] = imgArray[i]; } imgArray = newArray; newArray = null; } imgArray[size] = img ; redArray[size] = new ColorArray(img,ColorArray.TYPE_RED); greenArray[size] = new ColorArray(img,ColorArray.TYPE_GREEN); blueArray[size] = new ColorArray(img,ColorArray.TYPE_BLUE); size++; } public void remove(int index) { imgArray[index] = null; size--; } //注意index的合法性 public BufferedImage get(int index) { return imgArray[index] ; }}

ColorArray 二维数组类，存放并处理颜色矩阵

package drawBoard_test2;import java.awt.image.BufferedImage;public class ColorArray{ static final int TYPE_RED = 0; static final int TYPE_GREEN = 1; static final int TYPE_BLUE = 2; public int[][] array = {}; ColorArray(BufferedImage img , int type){ if(type == TYPE_RED){ array = new int[img.getWidth()][img.getHeight()]; for (int i = 0; i < img.getWidth(); i++) { for (int j = 0; j < img.getHeight(); j++) { array[i][j] = (img.getRGB(i,j)>>16) & 0xff; } } }else if(type == TYPE_GREEN){ array = new int[img.getWidth()][img.getHeight()]; for (int i = 0; i < img.getWidth(); i++) { for (int j = 0; j < img.getHeight(); j++) { array[i][j] = (img.getRGB(i,j)>>8) & 0xff; } } }else if(type == TYPE_BLUE){ array = new int[img.getWidth()][img.getHeight()]; for (int i = 0; i < img.getWidth(); i++) { for (int j = 0; j < img.getHeight(); j++) { array[i][j] = img.getRGB(i,j) & 0xff; } } } }}通过滑动条调整颜色，并绘制出来

@Override public void stateChanged(ChangeEvent e) { JSlider jSlider = (JSlider)e.getSource(); String s = jSlider.getToolTipText(); switch (s){ case "缩放比例": multiple = jSlider.getValue(); int[][] img = getImagePixel(fileName); BufferedImage bufferedImage = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg = bufferedImage.getGraphics(); drawImage_multiple(buffg,img); g.drawImage(bufferedImage,0,0,null); break; case "红色": multipleRed = jSlider.getValue(); BufferedImage bufferedImage1 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg1 = bufferedImage1.getGraphics(); drawImage_multiple_color(buffg1,imageArray); g.drawImage(bufferedImage1,0,0,null); break; case "绿色": multipleGreen = jSlider.getValue(); BufferedImage bufferedImage2 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg2 = bufferedImage2.getGraphics(); drawImage_multiple_color(buffg2,imageArray ); g.drawImage(bufferedImage2,0,0,null); break; case "蓝色": multipleBlue = jSlider.getValue(); BufferedImage bufferedImage3 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); Graphics buffg3 = bufferedImage3.getGraphics(); drawImage_multiple_color(buffg3,imageArray); g.drawImage(bufferedImage3,0,0,null); break; } }//注意：在图片打开的时候将从图片提取出来的BufferedImage放入imageArray中public void drawImage_multiple_color(Graphics g , ImageArray imageArray){ int index = imageArray.getSize()-1; int w = (drawJPanel.getWidth()- imageArray.get(index).getWidth())/2; int h = (drawJPanel.getHeight()- imageArray.get(index).getHeight())/2; int[][] red ; int[][] green; int[][] blue ; red = imageArray.multiple(multipleRed,imageArray.redArray[index]); green = imageArray.multiple(multipleGreen,imageArray.greenArray[index]); blue = imageArray.multiple(multipleBlue,imageArray.blueArray[index]); for (int i = 0; i < imageArray.get(index).getWidth(); i++) { for (int j = 0; j < imageArray.get(index).getHeight() ; j++) { g.setColor(new Color(red[i][j],green[i][j],blue[i][j])); g.drawRect(i+w,j+h,1,1); } }} 第十二步：旋转拿向右旋转来举例，我们要把数组向右旋转变成一个新数组，再输出到屏幕上。

case "向左旋转": BufferedImage bufferedImage15 = new BufferedImage(800,800,BufferedImage.TYPE_INT_ARGB); int img15[][] = getImagePixel(fileName); img15 = RotateRight(img15); Graphics buffg15 = bufferedImage15.getGraphics(); drawImage(buffg15,img15); g.drawImage(bufferedImage15,0,0,null); ImageShape imageShape15 = new ImageShape(); imageShape15.setBufferedImage(bufferedImage15); shapeList.add(imageShape15); break;public int[][] RotateRight(int[][] img){ int w = img.length; int h = img[0].length; int[][] newImg = new int[h][w]; for (int i = 0; i < w; i++) { for (int j = 0; j < h; j++) { newImg[h-j-1][w-i-1] = img[i][j]; } } return newImg;}![image](https://img2022.cnblogs.com/blog/2555328/202204/2555328-20220414151025986-1397523916.png)

效果图片：

一点点心得总结

1、开始写代码之前，一定要明确自己要实现什么功能，达到什么效果。
2、如何实现这样的效果。
3、实现过程中：当前实现的效果是否符合预期，如果不符合要重新制定计划。
4、搜集资料，撰写博客，发现自己的不足，旧知新学。

作者：classic123

链接：https://www.cnblogs.com/classicltl/p/16145023.html

标签：BufferedImageint