java在JFrame中生成方波

Question

我有一个低效的方波代码。我有两个按钮，一张桌子和一个类似坐标系的东西，正方形出现在这个坐标系中。我希望波浪能够实时滚动/移动，直到它到达坐标系的末端，而不是仅仅通过选择两个按钮来显示。另外，如果有人有更好的方法画方波，请告诉我

public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g;
    g2d.drawLine(20, 300, 20, 450);
    g2d.drawLine(20, 350, 400, 350);
    g2d.drawLine(20, 400, 400, 400);
    g2d.drawLine(20, 450, 400, 450);

    if (this.jButtonSTART.isSelected() & this.jButtonAND.isSelected()) {
            this.draw(g2d);
        }
}

public void draw(Graphics2D g2d) {
    boolean up = true;
    while (x <= 380) {
        g2d.setColor(Color.blue);
        if (x > 0 && x % 95 == 0) {
            up = !up;
            g2d.drawLine(20 + x, up ? 315 : 350 + y, 20 + x, up ? 350 : 315 + y);
        } else {
            if (up) {
                g2d.drawLine(20 + x, 315 + y, 21 + x, y + 315);
            } else {
                g2d.drawLine(20 + x, 350 + y, 21 + x, y + 350);
            }
        }
        x++;
    }
    x = 0;
}

Answer 1

绘制方波并移动它的简单方法：

1. 创建一个比GUI长的BuffereImage。它的长度应该与方波的周期相匹配，并且至少是显示它的GUI组件的两倍
2. 在JPanel的paintComponent方法替代范围内绘制，而不是绘制方法
3. 首先在覆盖中调用super的paintComponent方法
4. 您将使用g.drawImage(myImage, imageX, imageY, this)绘制图像，其中imageX和imageY是JPanel扩展绘图类的私有实例字段
5. 在Swing计时器中，使用计时器的每个滴答声（即每次调用其ActionListener的actionPerformed方法时）推进imageX
6. 然后在相同的actionPerformed方法中对图形JPanel调用repaint()
7. 完成了

例如，请注意，这段代码并不完全执行您试图执行的操作，而是显示了一个使用Swing计时器和paintComponent的Swing动画示例

import java.awt.Color;
import java.awt.Dimension;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.*;

@SuppressWarnings("serial")
public class MoveWave extends JPanel {
    private static final int PREF_W = 400;
    private static final int PREF_H = 200;
    private static final int TIMER_DELAY = 40;
    public static final int DELTA_X = 2;
    public static final int STARTING_MY_IMAGE_X = -PREF_W;
    private static final Color COLOR_1 = Color.RED;
    private static final Color COLOR_2 = Color.BLUE;
    private static final Color BG = Color.BLACK;
    private static final int CIRCLE_COUNT = 10;
    private BufferedImage myImage = null;
    private int myImageX = STARTING_MY_IMAGE_X;
    private int myImageY = 0;

    public MoveWave() {
        setBackground(BG);
        myImage = new BufferedImage(2 * PREF_W, PREF_H, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2 = myImage.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(new GradientPaint(0, 0, COLOR_1, 20, 20, COLOR_2, true));
        for (int i = 0; i < CIRCLE_COUNT; i++) {
            int x = (i * 2 * PREF_W) / CIRCLE_COUNT;
            int y = PREF_H / 4;
            int width = (2 * PREF_W) / CIRCLE_COUNT;
            int height = PREF_H / 2;
            g2.fillOval(x, y, width, height);
        }
        g2.dispose();
        new Timer(TIMER_DELAY, new TimerListener()).start();
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (myImage != null) {
            g.drawImage(myImage, myImageX, myImageY, this);
        }
    }
    @Override
    public Dimension getPreferredSize() {
        if (isPreferredSizeSet()) {
            return super.getPreferredSize();
        }
        return new Dimension(PREF_W, PREF_H);
    }

    private class TimerListener implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            myImageX += DELTA_X;
            if (myImageX >= 0) {
                myImageX = STARTING_MY_IMAGE_X;                        
            }
            repaint();
        }
    }

    private static void createAndShowGui() {
        JFrame frame = new JFrame("MoveWave");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new MoveWave());
        frame.setResizable(false);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}