今天想实现在图片上画框，并得到各个顶点，就想用JAVA来实现载入图片，并在图片上画线，画框，选择删除操作。
做下来发现有几个问题要注意：
（1），如何用JPANEL做画板，并且载入大图片时，能够有滚动条。
（2），绘图如何保存前一步的操作，以及怎么把矩形打散成线。对图片形的进一步操作
以下是代码，在ECLIPSE中实现
DrawFrame.java
package org.lee.rag;import java.awt.BasicStroke;import java.awt.BorderLayout;import java.awt.Color;import java.awt.Dimension;import java.awt.EventQueue;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.Rectangle;import java.awt.Stroke;import java.awt.image.BufferedImage;import javax.imageio.ImageIO;import javax.swing.BorderFactory;import javax.swing.BoxLayout;import javax.swing.ButtonGroup;import javax.swing.JFileChooser;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.border.EmptyBorder;import javax.swing.filechooser.FileNameExtensionFilter;import javax.swing.JButton;import javax.swing.JScrollPane;import java.awt.event.ActionListener;import java.awt.event.ActionEvent;import java.awt.event.KeyEvent;import java.awt.event.KeyListener;import java.awt.event.MouseAdapter;import java.awt.event.MouseEvent;import java.awt.event.MouseListener;import java.awt.event.MouseMotionListener;import java.io.IOException;import java.util.ArrayList;import java.util.Iterator;import java.util.List;import javax.swing.JRadioButton;public class DrawFrame extends JFrame {private JPanel contentPane;private ImagePanel imagePanel;private BufferedImage image=null;private Graphics g=null;private int preX=-1;private int preY=-1;private int currentX=-1;private int currentY=-1;private boolean hlineFlag=false;private boolean vlineFlag=false;private boolean rectFlag=false;private boolean modifyFlag=false;private ButtonPanel bp=new ButtonPanel("形状",new String[]{"横线","竖线","矩形","修改"});private List<LinkedPoint> lpList=new ArrayList<LinkedPoint>();private List<Line> lineList=new ArrayList<Line>();private Line currentLine=null;/** * Launch the application. */public static void main(String[] args) {EventQueue.invokeLater(new Runnable() {public void run() {try {DrawFrame frame = new DrawFrame();frame.setVisible(true);} catch (Exception e) {e.printStackTrace();}}});}/** * Create the frame. */public DrawFrame() {setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);setBounds(100, 100, 710, 569);contentPane = new JPanel();contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));contentPane.setLayout(new BorderLayout(0, 0));setContentPane(contentPane);JPanel panel = new JPanel();contentPane.add(panel, BorderLayout.NORTH);JButton openbtn = new JButton("open");openbtn.addActionListener(new ActionListener() {public void actionPerformed(ActionEvent e) {JFileChooser chooser = new JFileChooser(); FileNameExtensionFilter filter = new FileNameExtensionFilter( "JPG & GIF Images", "jpg", "gif"); chooser.setFileFilter(filter); int returnVal = chooser.showOpenDialog(rootPane); if(returnVal == JFileChooser.APPROVE_OPTION) { try {BufferedImage bImage=ImageIO.read(chooser.getSelectedFile());int width=bImage.getWidth();int height=bImage.getHeight();image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);imagePanel.setPreferredSize(new Dimension(width,height));g=image.getGraphics();g.drawImage(bImage,0,0,null);imagePanel.repaint();imagePanel.updateUI(); } catch (IOException e1) {e1.printStackTrace();} }}});panel.add(openbtn);JButton delBtn = new JButton("del");delBtn.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {// TODO Auto-generated method stubif(currentLine!=null){lineList.remove(currentLine);currentLine=null;}imagePanel.repaint();}});panel.add(delBtn);panel.add(bp);imagePanel=new ImagePanel();imagePanel.addMouseListener(new MouseListener(){@Overridepublic void mouseClicked(MouseEvent e) {// TODO Auto-generated method stubint x=e.getX();int y=e.getY();int srcY,srcX,destY,destX;for(int i=0;i<lineList.size();i++){Line line=lineList.get(i);if(x==line.getSrcX()){if(line.getSrcY()>line.getDestY()){srcY=line.getSrcY();destY=line.getDestY();}else{srcY=line.getDestY();destY=line.getSrcY();}if(y>=destY && y<=srcY){currentLine=line;}}if(y==line.getSrcY()){if(line.getSrcX()>line.getDestX()){srcX=line.getSrcX();destX=line.getDestX();}else{srcX=line.getDestX();destX=line.getSrcX();}if(x>=destX && x<=srcX){currentLine=line;}}}imagePanel.repaint();}@Overridepublic void mousePressed(MouseEvent e) {// TODO Auto-generated method stubcurrentLine=null;if(bp.getSelection().equals("横线")){hlineFlag=true;}if(bp.getSelection().equals("竖线")){vlineFlag=true;}if(bp.getSelection().equals("矩形")){rectFlag=true;}if(bp.getSelection().equals("修改")){modifyFlag=true;}preX=e.getX();preY=e.getY();}@Overridepublic void mouseReleased(MouseEvent e) {// TODO Auto-generated method stubif(hlineFlag || vlineFlag){lineList.add(new Line(preX,preY,currentX,currentY));LinkedPoint lp=new LinkedPoint(preX,preY);lp.add(new LinkedPoint(currentX,currentY));}if(rectFlag){lineList.add(new Line(preX,preY,currentX,preY));lineList.add(new Line(currentX,preY,currentX,currentY));lineList.add(new Line(preX,currentY,currentX,currentY));lineList.add(new Line(preX,currentY,preX,preY));LinkedPoint lp=new LinkedPoint(preX,preY);lp.add(new LinkedPoint(preX,currentY));lp.add(new LinkedPoint(currentX,preY));lp.add(new LinkedPoint(currentX,currentY));lpList.add(lp);}preX=-1;preY=-1;currentX=-1;currentY=-1;hlineFlag=false;vlineFlag=false;rectFlag=false;modifyFlag=false;}@Overridepublic void mouseEntered(MouseEvent e) {// TODO Auto-generated method stub}@Overridepublic void mouseExited(MouseEvent e) {// TODO Auto-generated method stub}});imagePanel.addMouseMotionListener(new MouseMotionListener(){@Overridepublic void mouseDragged(MouseEvent e) {// TODO Auto-generated method stubif(preX>0 && preY>0){if(hlineFlag){currentX=e.getX();currentY=preY;}if(vlineFlag){currentX=preX;currentY=e.getY();}if(rectFlag){currentX=e.getX();currentY=e.getY();}imagePanel.repaint();}}@Overridepublic void mouseMoved(MouseEvent e) {// TODO Auto-generated method stub}});imagePanel.setSize(new Dimension(800,1000));contentPane.add(new JScrollPane(imagePanel), BorderLayout.CENTER);}class ImagePanel extends JPanel{@Overridepublic void paintComponent(Graphics g){Graphics2D g2d=(Graphics2D) g.create();g2d.clearRect(0,0,this.getWidth(), this.getHeight());g2d.drawImage(image,0,0,null);g2d.setStroke(new BasicStroke(4.0f,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND));g2d.setColor(Color.red);int width=currentX-preX;int height=currentY-preY;if(rectFlag){g2d.drawRect(preX, preY, width, height);}if(hlineFlag){g2d.drawLine(preX, preY, currentX, currentY);}if(vlineFlag){g2d.drawLine(preX, preY, currentX, currentY);}for(int i=0;i<lineList.size();i++){Line line=lineList.get(i);g2d.drawLine(line.getSrcX(), line.getSrcY(), line.getDestX(), line.getDestY());}//画点if(currentLine!=null){g2d.setColor(Color.black);g2d.setStroke(new BasicStroke(1.0f,BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND));g2d.drawOval(currentLine.getSrcX()-2, currentLine.getSrcY()-2, 4, 4);g2d.drawOval(currentLine.getDestX()-2, currentLine.getDestY()-2, 4, 4);}g2d.dispose();}}class ButtonPanel extends JPanel{private ButtonGroup group;public ButtonPanel(String title,String[] option){setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(), title));setLayout(new BoxLayout(this,BoxLayout.X_AXIS));group=new ButtonGroup();for(int i=0;i<option.length;i++){JRadioButton b=new JRadioButton(option[i]);add(b);group.add(b);b.setActionCommand(option[i]);b.setSelected(i==0);}}public String getSelection(){return group.getSelection().getActionCommand();}}}
Line.java
package org.lee.rag;public class Line {private int srcX;private int srcY;private int destX;private int destY;public Line(){}public Line(int srcX, int srcY, int destX, int destY){this.srcX=srcX;this.srcY=srcY;this.destX=destX;this.destY=destY;}public int getSrcX() {return srcX;}public void setSrcX(int srcX) {this.srcX = srcX;}public int getSrcY() {return srcY;}public void setSrcY(int srcY) {this.srcY = srcY;}public int getDestX() {return destX;}public void setDestX(int destX) {this.destX = destX;}public int getDestY() {return destY;}public void setDestY(int destY) {this.destY = destY;}}
LinkedPoint.java
package org.lee.rag;public class LinkedPoint {private int x;private int y;private LinkedPoint currentPoint=null;//后一个节点private LinkedPoint nextPoint=null;public LinkedPoint(){init();}public LinkedPoint(int x,int y){this.x=x;this.y=y;init();}private void init(){currentPoint=this;}public boolean hasNext(){return (nextPoint==null) ? false : true;}public void add(LinkedPoint point){if(currentPoint.hasNext()){currentPoint=currentPoint.getNextPoint();}currentPoint.setNextPoint(point);}public int getX() {return x;}public void setX(int x) {this.x = x;}public int getY() {return y;}public void setY(int y) {this.y = y;}public LinkedPoint getNextPoint() {return nextPoint;}public void setNextPoint(LinkedPoint nextPoint) {this.nextPoint = nextPoint;}}
放弃那些不愿放弃的，容忍那些不可容忍的。
