AWT对处理位图

package com.main;

import javax.swing.*;
import javax.swing.event.MenuEvent;
import javax.swing.event.MenuListener;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;

public class MassageDialogDeom {

private final int AREA_WIDTH=500;
private final int AREA_HEIGHT=400;
    BufferedImage bufferedImage=null;
    private MyCanvas myCanvas=new MyCanvas();
    int preX=-1;
    int prey=-1;
private Color forceColor=Color.red;
    public void init(){
        Frame simple_mapping = new Frame("simple mapping");

        PopupMenu popupMenu = new PopupMenu();
        MenuItem red = new MenuItem("red");
        MenuItem green = new MenuItem("green");
        MenuItem blue = new MenuItem("blue");

        bufferedImage= new BufferedImage(AREA_WIDTH, AREA_HEIGHT, BufferedImage.TYPE_INT_BGR);
        //定义变量，记录鼠标上一次所处的坐标

        //通过位图获取Graphics
        Graphics graphics = bufferedImage.getGraphics();
        graphics.setColor(Color.WHITE);
        graphics.fillRect(0,0,AREA_WIDTH,AREA_HEIGHT);

        myCanvas.addMouseMotionListener(new MouseMotionAdapter() {
            @Override
            public void mouseDragged(MouseEvent e) {//鼠标按下并拖动时会被调用
                System.out.println("---"+e.getX()+"y"+e.getY());
                if(preX>0&&prey>0){
                    graphics.setColor(forceColor);
                    //画线条
                    graphics.drawLine(preX,prey,e.getX(),e.getY());
                    myCanvas.repaint();
                }
                preX=e.getX();
                prey=e.getY();
              
            }
        });
        //通过监听鼠标的移动，完成线条绘制

        //自定义一个类继承Canvas

        ActionListener actionListener=new AbstractAction() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String actionCommand = e.getActionCommand();
                switch (actionCommand){
                    case "red":
                        forceColor=Color.red;
                        break;
                    case "green":
                        forceColor=Color.green;
                        break;
                        case "blue":
                        forceColor=Color.blue;
                        break;
                }
            }
        };
        red.addActionListener(actionListener);
        green.addActionListener(actionListener);
        blue.addActionListener(actionListener);
        popupMenu.add(red);
        popupMenu.add(green);
        popupMenu.add(blue);
        //把colormenu设置给绘图区域
        myCanvas.add(popupMenu);
        myCanvas.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseReleased(MouseEvent e) {
                //当鼠标键抬起调用
                boolean popupTrigger = e.isPopupTrigger();
                if(popupTrigger){
                    popupMenu.show(myCanvas,e.getX(),e.getY());
                }
                preX=-1;
                prey=-1;
            }
        });
        myCanvas.setPreferredSize(new Dimension(AREA_WIDTH,AREA_HEIGHT));
        simple_mapping.add(myCanvas);
        simple_mapping.pack();
        simple_mapping.setVisible(true);

    }
    private class MyCanvas extends Canvas{
        @Override
        public void paint(Graphics g) {
            g.drawImage(bufferedImage,0,0,null);
        }
    }
    public static void main(String[] args) {
        new MassageDialogDeom().init();

    }
}