使用Swing和Graphics2D在Java中旋转滚轮？

Question

我正在研究一个可以围绕中心旋转轮子的课程。轮子是使用graphics2d创建的，但我无法弄清楚如何让轮子围绕中心旋转。目前，车轮旋转，但不完全是关于原点。

我的最终目标是制造轮子，使其成为多色的，以及围绕它的程序，但我的主要关注点是让旋转轮工作。如果你能指出我正确的方向，我将永远感激不尽！

这是我目前的代码：

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.swing.*;


public class RotateApp {

private static final int N = 3;

public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {

        public void run() {
            JFrame frame = new JFrame();
            frame.setLayout(new GridLayout(N, N, N, N));
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.add(new RotatePanel());
            frame.pack();
            frame.setVisible(true);
            System.out.println();
        }
    });
}
}


class RotatePanel extends JPanel implements ActionListener {

private static final int SIZE = 256;
private static double DELTA_THETA = Math.PI / 90;
private final Timer timer = new Timer(25, this);
private Image image = RotatableImage.getImage(SIZE);
private double dt = DELTA_THETA;
private double theta;

public RotatePanel() {
    this.setBackground(Color.lightGray);
    this.setPreferredSize(new Dimension(
        image.getWidth(null), image.getHeight(null)));
    this.addMouseListener(new MouseAdapter() {

        @Override
        public void mousePressed(MouseEvent e) {
            image = RotatableImage.getImage(SIZE);
            dt = -dt;
        }
    });
    timer.start();
}


public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2d = (Graphics2D) g;
    g2d.translate(this.getWidth() / 2, this.getHeight() / 2);
    g2d.rotate(theta);
    g2d.translate(-image.getWidth(this) / 2, -image.getHeight(this) / 2);
    g2d.drawImage(image, 0, 0, null);
}

public void actionPerformed(ActionEvent e) {
    theta += dt;
    repaint();
}

@Override
public Dimension getPreferredSize() {
    return new Dimension(SIZE, SIZE);
}

}

class RotatableImage {

private static final Random r = new Random();

static public Image getImage(int size) {
    BufferedImage bi = new BufferedImage(
        size, size, BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2d = bi.createGraphics();
    g2d.setRenderingHint(
        RenderingHints.KEY_ANTIALIASING,
        RenderingHints.VALUE_ANTIALIAS_ON);
    g2d.setPaint(Color.getHSBColor(r.nextFloat(), 1, 1));
    g2d.setStroke(new BasicStroke(10.0f));
    g2d.draw(new Line2D.Double(0, 100, 100, 100));
    g2d.draw(new Line2D.Double(100, 100, 200, 100));

    g2d.draw(new Line2D.Double(100, 0, 100, 100));
    g2d.draw(new Line2D.Double(100, 100, 100, 200));

    g2d.draw(new Line2D.Double(25, 25, 100, 100));
    g2d.draw(new Line2D.Double(100, 100, 175, 175));

    g2d.draw(new Line2D.Double(175, 25, 100, 100));
    g2d.draw(new Line2D.Double(100, 100, 25, 175));

    g2d.draw(new Ellipse2D.Double(0, 0, 200, 200));
    g2d.dispose();
    return bi;
}
}

Answer 1

另一答案