java - 如何让鼠标移动在 JPanel 内的多个不同 ImageIcons 上正常工作？

Question

我目前正在尝试使用 Swing 编写我的第一个非常简单的图像处理程序。应该可以浏览图像并将其添加为 ImageIcons，并在屏幕上移动这些图像。添加照片时应将其分层，单击图像应将其删除。

程序可以运行，但我遇到以下功能问题。

这是我的代码:

import javax.swing.*;
import java.awt.*;
import javax.swing.filechooser.FileNameExtensionFilter;
import java.awt.event.*;
import java.io.File;
import java.util.ArrayList;
import java.util.Collection;

class Image {
    private int x = 80;
    private int y = 80;
    private String filepath;
    private ImageIcon image;

    public Image(int x, int y, String filepath){
        this.x = x;
        this.y = y;
        this.filepath = filepath;
        image = new ImageIcon(filepath);
    }

    public Image(String filepath){
        this.filepath = filepath;
        image = new ImageIcon(filepath);
    }

    public void draw(Graphics g){
        g.drawImage(image.getImage(), x, y, null);

    }

    public void undraw (Graphics g, Color c ){
        g.setColor(c);
        g.fillRect(x,y,image.getIconWidth(), image.getIconHeight());

    }

    public boolean containsXY (int x, int y){

        if ( this.x <= x && this.y <= y){
            return true;
        }

        return false;
    }

    public void move (Graphics g, int x, int y) {
        undraw(g, Color.WHITE);
        this.x = x;
        this.y = y;

        draw(g);
    }

}


class PaintSurface extends JPanel implements MouseListener, MouseMotionListener {

    private int x, y;
    private JButton browse;
    private Collection <Image> images = new ArrayList<Image>();
    private final JFileChooser fc = new JFileChooser();
    private Image selected;

    public PaintSurface(JButton b){
        browse = b;
        addMouseListener(this);
        addMouseMotionListener(this);
        browse.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {

                FileNameExtensionFilter filter = new FileNameExtensionFilter("JPG & GIF", "jpg", "gif");
                fc.setFileFilter(filter);
                fc.showOpenDialog(browse);
                buttonPressed(fc);

            }
        });
    }

    public void paintComponent (Graphics g){
        super.paintComponent(g);

        for (Image i: images){
            i.draw(g);

        }

    }

    public void addImage(Image i){
        images.add(i);

        Graphics g = getGraphics();
        i.draw(g);

    }


    public void buttonPressed(JFileChooser fc){
        File selectedFile = fc.getSelectedFile();

        Image i = new Image(x, y, selectedFile.getAbsolutePath());

        addImage(i);
        repaint();
    }

    public Image findImage(int x, int y){
        for (Image i: images){
            if (i.containsXY(this.x, this.y)){
                return i;

            }

        }
        return null;
    }

    public boolean removeImage (Image i){

        Graphics g = getGraphics();
        i.undraw(g, Color.WHITE);

        return images.remove(i);
    }

    public void moveImage (Image i, int x, int y) { //

        i.move(getGraphics(), x, y);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        x = e.getX();
        y = e.getY();

        Image i = findImage(x, y);

        if (i != null) {
            removeImage(i);
        }
    }

    @Override
    public void mousePressed(MouseEvent e) {
        int x = e.getX();
        int y = e.getY();

        selected = findImage(x,y);
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        int x = e.getX();
        int y = e.getY();

        if (selected != null) {
            moveImage(selected,x,y);
        }
    }

    @Override
    public void mouseReleased(MouseEvent e) {
    }

    @Override
    public void mouseEntered(MouseEvent e) {

    }

    @Override
    public void mouseExited(MouseEvent e) {

    }

    @Override
    public void mouseMoved(MouseEvent e) {

    }
}


class GUI extends JFrame {

    public GUI(){
        super("ImageApp");

        JLabel instruction = new JLabel("Clicking anywhere on the screen will set the location for the next added image.");
        JButton browse = new JButton("Add image");
        JPanel panel1 = new JPanel();
        JPanel panel2 = new PaintSurface(browse);
        panel1.setLayout(null);
        panel2.setBackground(Color.WHITE);
        instruction.setAlignmentX(CENTER_ALIGNMENT);

        getContentPane().setBackground(Color.WHITE);
        getContentPane().add("North", instruction );
        getContentPane().add("South", browse);


        add(panel1);
        add(panel2);
        setBounds(300,0,800,800);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);
        setVisible(true);

    }

}

public class PhotoApp extends GUI {

    public static void main (String[] args){
        GUI PhotoApplication = new GUI();

    }
}

这些是问题:

• 当我添加多个图像时，鼠标功能突然停止工作，并且我无法移动任何图像。他们不知何故被“卡住”了。
• 当我添加了多张图片时，我只能控制(移动)最新添加的一张。
• 当单击删除图像时，即使我没有在图像内部单击而是在图像附近单击，该图像也会被删除。如果我在远离图像的地方单击，它不会被删除(所以它是有效的)。仅当单击图像内部时才应将其删除!
• 点击添加图像时，如果按“取消”，则会出现一堆错误
• 这些图片应该是相互层叠的，但是当我现在移动图像时，它会“删除”旧图像。

有人可以帮忙吗？我会非常感激，因为我已经被这个问题困扰了很长时间。

Answer 1

我已经针对您的一些问题概述了有问题的代码。

When I have added several images, I can only control (move) the latest added one.

您只返回一个:public Image findImage(int x, int y) 。并且:

When clicking to remove an image, it is removed even though I don't click inside the image but close to the image. It isn't removed if I click far away from the image (so it's sort of working). It is only supposed to be removed if clicking inside the image!

您的containsXY()这里似乎很困惑:if ( this.x <= x && this.y <= y) 。提示:x = 0 且 y = 0 的 1 像素方形图像不包含 x = 50、y = 50。这导致了我解决的第一个问题的一部分。

When clicking to add an image, if I press "Cancel" I get a bunch of errors

如果您不选择一个文件，它将不会返回文件: File selectedFile = fc.getSelectedFile();

The pictures are supposed to be layered on top of each other, but when I move an image around now it "erases" the older images.

您是undraw与白色搭配: g.fillRect(x,y,image.getIconWidth(), image.getIconHeight());