在 Java 中使用鼠标旋转一行

Question

给出以下代码：

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

public class DragRotation extends JPanel {
Rectangle2D.Double rect = new Rectangle2D.Double(100,75,200,160);
AffineTransform at = new AffineTransform();

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(rect);
    g2.setPaint(Color.red);
    g2.draw(at.createTransformedShape(rect));
}

public static void main(String[] args) {
    DragRotation test = new DragRotation();
    test.addMouseListener(test.rotator);
    test.addMouseMotionListener(test.rotator);
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.getContentPane().add(test);
    f.setSize(400,400);
    f.setLocation(200,200);
    f.setVisible(true);
}

private MouseInputAdapter rotator  = new MouseInputAdapter() {
    Point2D.Double center = new Point2D.Double();
    double thetaStart = 0;
    double thetaEnd = 0;
    boolean rotating = false;

    public void mousePressed(MouseEvent e) {
        Point p = e.getPoint();
        Shape shape = at.createTransformedShape(rect);
        if(shape.contains(p)) {
            Rectangle r = shape.getBounds();
            center.x = r.getCenterX();
            center.y = r.getCenterY();
            double dy = p.y - center.y;
            double dx = p.x - center.x;
            thetaStart = Math.atan2(dy, dx) - thetaEnd;
            System.out.printf("press thetaStart = %.1f%n",
                               Math.toDegrees(thetaStart));
            rotating = true;
        }
    }

    public void mouseReleased(MouseEvent e) {
        rotating = false;
        double dy = e.getY() - center.y;
        double dx = e.getX() - center.x;
        thetaEnd = Math.atan2(dy, dx) - thetaStart;
        System.out.printf("release thetaEnd = %.1f%n",
                           Math.toDegrees(thetaEnd));
    }

    public void mouseDragged(MouseEvent e) {
        if(rotating) {
            double dy = e.getY() - center.y;
            double dx = e.getX() - center.x;
            double theta = Math.atan2(dy, dx);
            at.setToRotation(theta - thetaStart, center.x, center.y);
            repaint();
        }
    }
};
}

如果我换行： Rectangle2D.Double rect = new Rectangle2D.Double(100,75,200,160); 到 Line2D.Double rect = new Line2D.Double(100,75,200,160);为了创建一条二维线。 之后我应该如何修改代码，以便它能够获得鼠标在线条上的坐标并使整个代码适用于线条的旋转。

谢谢！

Answer 1

为了确定旋转，您使用shape.contains(p) 它适用于矩形，但不适用于直线，因为我认为很难指向直线内。

你需要为一行的旋转标志指定一些区域，类似于下一个：

if(rect.x1 < p.x && rect.x2 > p.x 
        && rect.y1 < p.y && rect.y2 > p.y){
}

而不是

if(shape.contains(p)) {
}

在您的 mousePressed() 方法中。