java 图形化小工具Abstract Window Toolit 画笔 处理位图

具体编程来处理位图

知识点：

实现逻辑：

• 画板上的图片 new BufferedImage(canvasWidth,canvasHeight,BufferedImage.TYPE_INT_BGR);
• 画板Canvas的paint方法用画笔Graphics g  使用方法drawImage更新图片。
• 使用图片image的getGraphics();方法得到的图片画笔进行在图片上作画。    转化为Graphics2D 画笔
• 鼠标移动的最近两点之间画直线，鼠标移动之间很短，展示效果为曲线。

图片画笔(保留图片本身已画图基础上新增作画)：

• 图片颜色填充为白色 imageGraphics.fillRect(0, 0, canvasWidth, canvasHeight);
• 画笔粗细imageGraphics.setStroke(new BasicStroke(5f));
• 画笔颜色imageGraphics.setColor(fontColor);
• 画笔画直线mageGraphics.drawLine(drawX, drawY, e.getX(), e.getY());

菜单组件：

• 右键菜单 popupMenu.show(canvas,e.getX(), e.getY());

鼠标事件应用：

MouseListener鼠标事件

• • mouseReleased 松开鼠标
  • e.isPopupTrigger()右键松开

ActionListener 鼠标左键点击触发

WindowListener监听器windowClosing() 关闭窗口事件触发

demo：

import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;

/**
 * @ClassName DrawCanvasTest
 * @projectName: object1
 * @author: Zhangmingda
 * @description： XXX
 * date: 2021/5/8.
 */
public class DrawCanvasTest {
    /**
     * 窗口
     */
    private Frame frame = new Frame("手绘程序");
    /**
     * 定义画板
     */
    private final int canvasWidth = 600;
    private final int canvasHeight = 400;
    private Canvas canvas = new DrawCanvas();
    /**
     * 定义图片
     */
    private BufferedImage image = new BufferedImage(canvasWidth,canvasHeight,BufferedImage.TYPE_INT_BGR);
    /**
     * 获取图片对应的画笔，画笔的初始位置,初始颜色
     */
    private Graphics2D imageGraphics = (Graphics2D) image.getGraphics();
    private int drawX = -1;
    private int drawY = -1;
    private Color fontColor = new Color(255);
    /**
     * 画笔右键菜单
     */
    PopupMenu popupMenu = new PopupMenu();
    MenuItem redItem = new MenuItem("红色");
    MenuItem greenItem = new MenuItem("绿色");
    MenuItem blueItem = new MenuItem("蓝色");

    /**
     * 定义画板子类，定义画图图片
     */
    private class DrawCanvas extends Canvas {
        @Override
        public void paint(Graphics g) {
            g.drawImage(image,0, 0, null);
        }
    }

    private void start(){
        /**
         * 画板大小设置
         */
        canvas.setSize(canvasWidth, canvasHeight);
        frame.add(canvas);
        /**
         * 设置画笔粗细
         */
        imageGraphics.setStroke(new BasicStroke(5f));
        /**
         * 画笔右键菜单组合。添加到窗口
         */
        popupMenu.add(redItem);
        popupMenu.add(greenItem);
        popupMenu.add(blueItem);
        frame.add(popupMenu);
        /**
         * 画板中图片背景画成白色
         */
        imageGraphics.fillRect(0, 0, canvasWidth, canvasHeight);
        /**
         * 按下鼠标拖动时画图
         */
        canvas.addMouseMotionListener(new MouseAdapter() {
            //按下鼠标拖动
            @Override
            public void mouseDragged(MouseEvent e) {
                /**
                 * 如果位置不在初始位置，开始画图
                 */
                if (drawX != -1 && drawY != -1){
                    imageGraphics.setColor(fontColor);
                    imageGraphics.drawLine(drawX, drawY, e.getX(), e.getY());
                    canvas.repaint();
                }//移动画笔位置到当前鼠标位置
                drawX = e.getX();
                drawY = e.getY();
            }
        });
        /**
         * 松开鼠标画笔归位-1；-1；
         */
        canvas.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseReleased(MouseEvent e) {
                drawX = -1;
                drawY = -1;
                //如果是右键松开弹出选择颜色的弹框
                if (e.isPopupTrigger()){
                    popupMenu.show(canvas,e.getX(), e.getY());
                }
            }
        });

        /**
         * 右键菜单绑定监听器，改变画笔颜色
         */
        ActionListener fontColorListener = actionEvent -> {
            switch (actionEvent.getActionCommand()){
                case "红色":
                    fontColor = new Color(255,0,0);
                    break;
                case "绿色":
                    fontColor = new Color(0,250,0);
                    break;
                case "蓝色":
                    fontColor = new Color(0,0,255);
                    break;
            }
        };
        redItem.addActionListener(fontColorListener);
        greenItem.addActionListener(fontColorListener);
        blueItem.addActionListener(fontColorListener);

        /**
         * 窗口关闭
         */
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                System.out.println("窗口关闭");
                System.exit(0);
            }
        });
        /**
         * 窗口位置大小
         */
        frame.setLocation(400,300);
        frame.pack();
        frame.setVisible(true);
    }
    public static void main(String[] args) {
        new DrawCanvasTest().start();
    }
}