我想在背景图像上绘制可拖动的 JComponent

Posted 2023-05-08

【中文标题】我想在背景图像上绘制可拖动的 JComponent

【英文标题】：I want to draw draggable JComponent on background image

【发布时间】：2014-07-28 00:50:59

【问题描述】：

有一个是动物园，另一个是动物的代码（老虎和鹰现在是相同的代码，所以我只写Tiger.java）。 。 Draggable JComponent 是在框架上工作的，而不是在图像上工作的。首先，我单击图像然后绘制我的动物，其次，在我绘制了许多动物之后，我可以将我的动物拖放到图像上的任何位置。请教我怎么画。

---

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;

class BgPanel extends JPanel

    Image bg = new ImageIcon("c:\\back.jpg").getImage();
    public void paintComponent(Graphics g)
    
        g.drawImage(bg,0,0,getWidth(),getHeight(),this);
    


public class Zoo extends JFrame implements ActionListener

    Container c;
    JFrame frame = new JFrame();
    JComboBox comBox = new JComboBox();
    drawCanvas can = new drawCanvas();
    saving_drawing saving=new saving_drawing();
    Tiger tiger;
    Eagle eagle;
    Point point;

    ArrayList<saving_drawing> arr_saving = new ArrayList();

    Zoo()
    
        JPanel bgPanel = new BgPanel();
        bgPanel.setLayout(new BorderLayout());
        comBox.addItem("Tiger");
        comBox.addItem("Eagle");
        comBox.addActionListener(this);

        frame.setContentPane(bgPanel);

        bgPanel.add(comBox, BorderLayout.SOUTH);
        bgPanel.add(can, BorderLayout.CENTER);


        frame.setSize(500,500);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("Zoo");
        frame.setVisible(true);
    
    public void actionPerformed(ActionEvent e) 
    
        if("Tiger".equals(comBox.getSelectedItem()))
        
              saving.drawChoice=1;
        
        else if("Eagle".equals(comBox.getSelectedItem()))
        
              saving.drawChoice=2;
        

    
    class drawCanvas extends JComponent
    
        public drawCanvas()
        
            this.addMouseListener(new MouseListener()
            
                public void mouseClicked(MouseEvent e) 
                
                    count++;
                    if(count!=0)
                    
                    saving.point=e.getPoint();

                    arr_saving.add(new saving_drawing(saving.drawChoice,saving.point));
                    repaint();
                    System.out.println("click");
                    
                
                public void mouseEntered(MouseEvent e) 
                public void mouseExited(MouseEvent e) 
                public void mousePressed(MouseEvent e)
                public void mouseReleased(MouseEvent e)
            );
        
        public void paintComponent(Graphics g)
        
            Graphics2D g2 = (Graphics2D)g;

            for(int i=0;i<count;i++)
            
                saving.drawChoice=arr_saving.get(i).drawChoice;
                saving.point=arr_saving.get(i).point;

                if(saving.drawChoice==1)
                
                    tiger=new Tiger(saving.point);
                    //frame.add(tiger);
                    //frame.setVisible(true);
                    //tiger.draw(g2);
                    //can.add(tiger);
                    tiger.paintComponent(g2);
                    //I'don't know what to do for drawing my tiger
                
                if(saving.drawChoice==2)
                
                    eagle=new Eagle(saving.point);
                    eagle.draw(g2);
                

            

        
    
    class saving_drawing
    
        int drawChoice;

        Point point;
        saving_drawing()
        saving_drawing(int dc, Point p)
        
            this.drawChoice = dc;
            this.point=p;
        
    
    public static void main(String [] args)
    
        Zoo test = new Zoo();
    

---

import java.awt.*;

import javax.swing.*;

import java.awt.event.*;
public class Tiger extends JComponent implements MouseListener

     private boolean draggable = true;

        protected Cursor draggingCursor = Cursor
               .getPredefinedCursor(Cursor.HAND_CURSOR);
        protected boolean overbearing = false;

    save_drawing save = new save_drawing();

    Tiger(Point point)
    

        save.point=point;


        addMouseListener(this);
        addDragListeners();
        setOpaque(true);

    
    private void addDragListeners()

    


        final Tiger handle = this;

        addMouseMotionListener(new MouseAdapter()

        
           public void mouseMoved(MouseEvent e)

           

               save.point = e.getPoint();

           setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));

           
           public void mouseDragged(MouseEvent e)

           

               int anchorX = save.point.x;

               int anchorY = save.point.y;
               Point parentOnScreen = getParent().getLocationOnScreen();

               Point mouseOnScreen = e.getLocationOnScreen();

               Point position = new Point(mouseOnScreen.x - parentOnScreen.x

                       - anchorX, mouseOnScreen.y - parentOnScreen.y - anchorY);

               setLocation(position);

               if (overbearing)

               

                   getParent().setComponentZOrder(handle, 0);
                   System.out.println("check");
                   repaint();

               

           

        );

    

    public void paintComponent(Graphics g)
    
        Graphics2D g2 = (Graphics2D)g;
        super.paintComponent(g);

        if (isOpaque())

        
           g.setColor(Color.black);
           g.fillRect(save.point.x, save.point.y, 50, 50);
        

    
    class save_drawing
    
        Point point;


    
    public void mouseClicked(MouseEvent e) 
    

        save.point=e.getPoint();

        repaint();
    
    public void mouseEntered(MouseEvent arg0)
    public void mouseExited(MouseEvent arg0) 
    
    @Override
    public void mousePressed(MouseEvent arg0) 
    
    @Override
    public void mouseReleased(MouseEvent arg0) 
    
     private void removeDragListeners()

        
            for (MouseMotionListener listener : this.getMouseMotionListeners())
            
               removeMouseMotionListener(listener);
            
            setCursor(Cursor.getDefaultCursor());
        

【参考方案1】：

要在面板周围拖动组件，您可以使用Component Mover。