拖放多个/不同的组件

Question

This the code of my program. can you give some tips to make the other rectangles can move like the 1st one

Note: The 1st Rectangle is the only one can be drag and drop

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.MouseInputAdapter;

public class GraphicDragAndDrop extends JPanel {

        Rectangle and = new Rectangle(5,5,75,75);
        Rectangle or = new Rectangle(5,105,75,75);
        Rectangle xnor = new Rectangle(5,205,75,75);
        Rectangle nand = new Rectangle(5,305,75,75);
        Rectangle xor = new Rectangle(5,405,75,75);
        Rectangle inverter = new Rectangle(5,505,75,75);

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(Color.blue);
        g2.draw(and);

         Graphics2D g3 = (Graphics2D)g;
        g3.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g3.setPaint(Color.red);
        g3.draw(or);

        Graphics2D g4 = (Graphics2D)g;
        g4.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g4.setPaint(Color.blue);
        g4.draw(xnor);

        Graphics2D g5 = (Graphics2D)g;
        g5.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g5.setPaint(Color.red);
        g5.draw(nand);

        Graphics2D g6 = (Graphics2D)g;
        g6.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g6.setPaint(Color.blue);
        g6.draw(xor);


        Graphics2D g7 = (Graphics2D)g;
        g7.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g7.setPaint(Color.red);
        g7.draw(inverter);
    }

    public void setRect(int x, int y) {

       and.setLocation(x, y);
             repaint();

    }

    public static void main(String[] args) {
        GraphicDragAndDrop test = new GraphicDragAndDrop();
        new GraphicDragController(test);
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(test);
        f.setSize(400,400);
        f.setLocation(100,100);
        f.setVisible(true);
    }
}

class GraphicDragController extends MouseInputAdapter {
    GraphicDragAndDrop component;
    Point offset = new Point();
    boolean dragging = false;

    public GraphicDragController(GraphicDragAndDrop gdad) {
        component = gdad;
        component.addMouseListener(this);
        component.addMouseMotionListener(this);
    }

    public void mousePressed(MouseEvent e) {
        Point p = e.getPoint();
        Rectangle r = component.and;
        Rectangle a = component.or;
        if(r.contains(p)) {
            offset.x = p.x - r.x;
            offset.y = p.y - r.y;
            dragging = true;
    }
    }
    public void mouseReleased(MouseEvent e) {
        dragging = false;
    }

    public void mouseDragged(MouseEvent e) {
        if(dragging) {
            int x = e.getX() - offset.x;
            int y = e.getY() - offset.y;
            component.setRect(x, y);
        }


    }
}

All kinds of help will be appreciated Thanks :)

Answer 1

The first Rectangle is the only one that can be dragged because you have hard coded logic in your class that always refers to the first Rectangle.

You need to change the whole design of your class:

1. Don't hard code the rectangles. You will need an ArrayList to keep track of all the Rectangles and the color of each Rectangle

2. In you MouseListener code you will then need to iterate through this List to find out which Rectangle you clicked on by using the contains(...) method of the Rectangle and the mouse point from the MouseEvent.

3. Once you find the Rectangle that was clicked you will then need to change your code to do the dragging on this Rectangle, not the hard coded "and" variable that you are using now.

4. The paintComponent() logic will need to be changed to iterate through the ArrayList to paint each Rectangle. You should get this part of your code restructured first before you attempt to fix the dragging problem. You may want to check out Playing With Shapes for some ideas of how to paint Shape objects from an ArrayList.

There are probably other problems but hopefully that will get you started in the right direction.