Java Swing PaintComponent 旋转 jlabel

Question

我正在重写 Jpanel 的绘图组件，以便绘制和旋转一些图像，但是它会产生旋转其他东西(例如添加到 JPanel 的 JLabels 等)的不良副作用。我尝试在绘制图像后旋转回来，但 JLabels似乎有点抖动。

请注意，我围绕图像内的不同点(而不是图像的中心)旋转每个图像，因此在图像缓冲区内旋转图像不合适？

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

    g2.rotate(Math.toRadians(+(angle)), 137, 188);
    g2.drawImage(image1, 125, 131, this);
    g2.rotate(Math.toRadians(-(angle)), 137, 188);   

    g2.rotate(Math.toRadians(+(angle2)), 137, 188);
    g2.drawImage(image2, 125, 131, this);
    g2.rotate(Math.toRadians(-(angle2)), 137, 188);   

}

Answer 1

您可以做一些事情

1. 创建 Graphics 上下文的副本，使用诸如 Graphics2D g2d = (Graphics2D)g.create(); 之类的内容。完成绘制后，在副本上调用 Graphics#dispose 以释放它可能已分配的所有资源。这基本上允许您更改副本的属性，而不影响原始副本，但仍然绘制到相同的缓冲区。
2. 从 Graphics2D 获取原始 AffineTransform 的副本，然后您可以应用自己的 AffineTransform 并在完成后重置它，请参阅Graphics2D#get/setTransform

例如...

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import java.awt.geom.Path2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class TestRotate01 {

    public static void main(String[] args) {
        new TestRotate01();
    }

    public TestRotate01() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private CrossShape prop;

        private double angle;

        public TestPane() {
            prop = new CrossShape(50, 50);
            Timer timer = new Timer(40, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    angle += 5;
                    repaint();
                }
            });
            timer.start();
        }

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

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            AffineTransform current = g2d.getTransform();

            int x = 25;
            int y = (getHeight() - prop.getBounds().height) / 2;

            AffineTransform at = new AffineTransform();
            at.translate(x, y);
            at.rotate(Math.toRadians(angle), prop.getBounds().width / 2, prop.getBounds().height / 2);
            g2d.setTransform(at);
            g2d.setColor(Color.RED);
            g2d.draw(prop);

            // Reset...
            // Equally, you could dispose of the g2d and create a new copy
            g2d.setTransform(current);

            x = getWidth() - 25 - prop.getBounds().width;
            y = (getHeight() - prop.getBounds().height) / 2;

            at = new AffineTransform();
            at.translate(x, y);
            at.rotate(Math.toRadians(-angle), prop.getBounds().width / 2, prop.getBounds().height / 2);
            g2d.setTransform(at);
            g2d.setColor(Color.BLUE);
            g2d.draw(prop);

            g2d.dispose();
        }

    }

    public class CrossShape extends Path2D.Double {

        public CrossShape(int width, int height) {

            moveTo(0, 0);
            lineTo(width, height);
            moveTo(width, 0);
            lineTo(0, height);

        }

    }

}