围绕点旋转三角形java

The red line is simple a guide to show that the tip of the triangle is point towards the mouse...

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.geom.AffineTransform;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class DrawTriangle extends JFrame {

    /**
     * The x points.
     */
    private int[] xPoints = new int[]{0, 25, 50};

    /**
     * The y points.
     */
    private int[] yPoints = new int[]{50, 0, 50};

    double angle = 0f;

    /**
     * Instantiates a new draw triangle.
     */
    public DrawTriangle() {
        super("Dimitry Rakhlei");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setContentPane(new DrawTrianglePanel());
        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    /**
     * The Class DrawTrianglePanel.
     */
    private class DrawTrianglePanel extends JPanel implements MouseListener,
                    MouseMotionListener {

        private Point clickPoint;

        /**
         * Instantiates a new draw triangle panel.
         */
        public DrawTrianglePanel() {
            addMouseListener(this);
            addMouseMotionListener(this);
            clickPoint = new Point(100, 100);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        protected Dimension getTriangleSize() {

            int maxX = 0;
            int maxY = 0;
            for (int index = 0; index < xPoints.length; index++) {
                maxX = Math.max(maxX, xPoints[index]);
            }
            for (int index = 0; index < yPoints.length; index++) {
                maxY = Math.max(maxY, yPoints[index]);
            }
            return new Dimension(maxX, maxY);
        }

        /**
         * Drawing the triangle.
         *
         * @param g the g
         * @see javax.swing.JComponent#paintComponent(java.awt.Graphics)
         */
        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);

            Graphics2D g2d = (Graphics2D) g.create();
            AffineTransform at = new AffineTransform();
            Dimension size = getTriangleSize();
            int x = clickPoint.x - (size.width / 2);
            int y = clickPoint.y - (size.height / 2);
            at.translate(x, y);
            at.rotate(Math.toRadians(angle), clickPoint.x - x, clickPoint.y - y);
            g2d.setTransform(at);
            g2d.drawPolygon(xPoints, yPoints, 3);
            // Guide
            g2d.setColor(Color.RED);
            g2d.drawLine(size.width / 2, 0, size.width / 2, size.height / 2);
            g2d.dispose();

        }

        /**
         * (non-Javadoc).
         *
         * @param e the e
         * @see java.awt.event.MouseListener#mousePressed (java.awt.event.MouseEvent)
         */
        @Override
        public void mousePressed(MouseEvent e) {
            System.out.println("Mouse pressed called");
            //          clickPoint = e.getPoint();
            repaint();

        }

        /**
         * (non-Javadoc).
         *
         * @param e the e
         * @see java.awt.event.MouseListener#mouseReleased (java.awt.event.MouseEvent)
         */
        @Override
        public void mouseReleased(MouseEvent e) {
            System.out.println("Mouse released called");
        }

        /**
         * (non-Javadoc).
         *
         * @param e the e
         * @see java.awt.event.MouseMotionListener#mouseDragged (java.awt.event.MouseEvent)
         */
        public void mouseDragged(MouseEvent e) {
            System.out.println("Mouse dragged called");

            angle = -Math.toDegrees(Math.atan2(e.getPoint().x - clickPoint.x, e.getPoint().y - clickPoint.y)) + 180;

            repaint();
        }

        /**
         * (non-Javadoc).
         *
         * @param e the e
         * @see java.awt.event.MouseListener#mouseEntered (java.awt.event.MouseEvent)
         */
        public void mouseEntered(MouseEvent e) {
            System.out.println("Mouse Entered.");
        }

        /**
         * (non-Javadoc).
         *
         * @param e the e
         * @see java.awt.event.MouseListener#mouseExited (java.awt.event.MouseEvent)
         */
        public void mouseExited(MouseEvent e) {
            System.out.println("Mouse exited.");
        }

        /**
         * (non-Javadoc).
         *
         * @param e the e
         * @see java.awt.event.MouseListener#mouseClicked (java.awt.event.MouseEvent)
         */
        public void mouseClicked(MouseEvent e) {
        }

        /**
         * (non-Javadoc).
         *
         * @param e the e
         * @see java.awt.event.MouseMotionListener#mouseMoved (java.awt.event.MouseEvent)
         */
        public void mouseMoved(MouseEvent e) {
        }

    }

    /**
     * The main method.
     *
     * @param args the arguments
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                new DrawTriangle();
            }
        });
    }

}

现在，在你跳到我头上抱怨解决方案太复杂"之前，请理解我是个白痴，说真的，我 2 岁的孩子对基础数学的掌握比我还好，这就是我能想出的最简单的解决方案不会融化我的大脑并使用双阵列多边形 API.就个人而言，我会使用 Shape API，但这不是你开始使用的......