摇摆动画优化

Question

我一直在使用一个简单的动画Timer上JComponent。但是，当观看动画时，我会遇到难以置信的震荡。我应该采取什么步骤来优化此代码？

MyAnimationFrame

import javax.swing.*;

public class MyAnimationFrame extends JFrame {
    public MyAnimationFrame() {
        super("My animation frame!");
        setSize(300,300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        add(new AnimationComponent(0,0,50,50));
        setVisible(true);
    }

    public static void main(String[] args) {
        MyAnimationFrame f = new MyAnimationFrame();
    }
}

AnimationComponent

import javax.swing.*;
import java.awt.*;

public class AnimationComponent extends JComponent implements ActionListener {
    private Timer animTimer;
    private int x;
    private int y;
    private int xVel;
    private int yVel;
    private int width;
    private int height;
    private int oldX;
    private int oldY;

    public AnimationComponent(int x, int y, int width, int height) {
        this.x = x;
        this.y = y;
        this.height = height;
        this.width = width;

        animTimer = new Timer(25, this);
        xVel = 5;
        yVel = 5;

        animTimer.start();
    }

    @Override
    public void paintComponent(Graphics g) {
        g.fillOval(x,y,width,height);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        oldX = x;
        oldY = y;

        if(x + width > getParent().getWidth() || x < 0) {
             xVel *= -1;
        }

        if(y + height > getParent().getHeight() || y < 0) {
            yVel *= -1;
        }

        x += xVel;
        y += yVel;

        repaint();
    }
}

不知道这是否重要，但是我正在使用OpenJDK 1.8.0_121版本。

任何帮助表示赞赏。

Answer 1

在与Yago进行了精彩的讨论之后，我发现问题围绕多个领域展开，很大程度上归因于Java将更新与操作系统和硬件同步的能力，有些是您可以控制的，有些是无法控制的。

受到Yago的示例以及我关于“计时框架”工作原理的“记忆”的启发，我通过提高帧速率（至5毫秒，〜=
200fps）并减小变化增量来测试代码，结果与使用“计时框架”相同，但这使您拥有了原始设计的灵活性。

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class Test {

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

    public Test() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame("Test");
                frame.add(new AnimationComponent(0, 0, 50, 50));
                frame.setSize(300, 300);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class AnimationComponent extends JComponent implements ActionListener {

        private Timer animTimer;
        private int x;
        private int y;
        private int xVel;
        private int yVel;
        private int width;
        private int height;
        private int oldX;
        private int oldY;

        public AnimationComponent(int x, int y, int width, int height) {
            this.x = x;
            this.y = y;
            this.height = height;
            this.width = width;

            animTimer = new Timer(5, this);
            xVel = 1;
            yVel = 1;

            animTimer.start();
        }

        @Override
        public void paintComponent(Graphics g) {
            Graphics2D g2d = (Graphics2D) g.create();
            RenderingHints hints = new RenderingHints(
                    RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON
            );
            g2d.setRenderingHints(hints);
            g2d.fillOval(x, y, width, height);
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            oldX = x;
            oldY = y;

            if (x + width > getParent().getWidth() || x < 0) {
                xVel *= -1;
            }

            if (y + height > getParent().getHeight() || y < 0) {
                yVel *= -1;
            }

            x += xVel;
            y += yVel;

            repaint();
        }
    }
}

如果您需要进一步降低速度，然后进一步降低变化量，则意味着您必须改用doubles，这将导致Shape的API支持双精度值

您应该使用哪个？随你（由你决定。Timing
Framework确实非常适合在一段时间内进行线性动画处理，您知道要从一种状态进入另一种状态。对于游戏之类的东西来说，状态不是很好，因为对象的状态可能会从我的周期更改为另一个周期。我敢肯定您可以做到，但是使用简单的“主循环”概念会容易得多-
IMHO