java - 使用 java 小程序的连续动画

Question

我想在 Java 小程序中创建移动卡车的连续动画。在这种情况下，卡车应该在消失后立即从另一侧重新出现。我尝试使用一辆卡车，但只有在从一侧完全消失后，它才会出现在另一侧。因此，我使用了两个。

以下是我的代码:

public class prc1 extends Applet implements Runnable{
Thread t;
int x=0;
int y=0;
int i;
public void start(){
    t = new Thread(this);
    t.start();
}
public void paint(Graphics g){
    g.setColor(Color.gray);
    g.fillRect(x,10,70,45);
    g.setColor(Color.yellow);
    g.fillRoundRect(50+x,15,35,35,10,10);
    g.setColor(Color.black);
    g.fillArc(5+x,50,10,10,0,360);
    g.fillArc(55+x,50,10,10,0,360);

    g.setColor(Color.gray);
    g.fillRect(y,10,70,45);
    g.setColor(Color.yellow);
    g.fillRoundRect(50+y,15,35,35,10,10);
    g.setColor(Color.black);
    g.fillArc(5+y,50,10,10,0,360);
    g.fillArc(55+y,50,10,10,0,360);
}
public void run(){
    try{
        y=-90;
        x=0;    
        for(; ;){
            Thread.sleep(100);
            repaint();
            run();
            x=x+5;
            if(x==400){
                for(; ;){
                    y=y+5;
                    Thread.sleep(100);
                    repaint();
                    run();
                    x=x-5;
                    if(x==0){
                        y=-90;      
                        break;
                    }
                }
            }

        }
    }catch(InterruptedException e){ }
  }
}

现在的问题是卡车根本不动。

Answer 1

所以基本思路是，您需要确定卡车何时开始离开可视区域，然后计算“溢出”量，这样您就可以在从溢出。

我已经分解了你的代码，所以 Truck 是它自己的类，这使得它更容易处理，并允许对绘画过程有更多的控制。

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 javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

    public Test() {
        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 Truck truck;

        public TestPane() {
            truck = new Truck();
            Timer timer = new Timer(40, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    truck.update(getSize());
                    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();
            truck.paint(g2d);
            g2d.dispose();
        }

    }

    public class Truck {

        private int x, y;
        // I had to calculate these
        private int width = 85;
        private int height = 65;

        private int xDelta = 4;

        private int xOverFlow = 0;

        public void update(Dimension bounds) {
            x += xDelta;
            if (x > bounds.width) {
                x = 0;
            }

            if (x + width > bounds.width) {
                xOverFlow = (x + width) - bounds.width;
            } else {
                xOverFlow = -1;
            }
        }

        public void paint(Graphics2D g) {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.translate(x, y);
            paintTruck(g2d);
            g2d.dispose();

            if (xOverFlow > 0) {
                g2d = (Graphics2D) g.create();
                g2d.translate(xOverFlow - width, y);
                paintTruck(g2d);
                g2d.dispose();
            }
        }

        protected void paintTruck(Graphics2D g2d) {
            g2d.setColor(Color.gray);
            g2d.fillRect(0, 10, 70, 45);
            g2d.setColor(Color.yellow);
            g2d.fillRoundRect(50, 15, 35, 35, 10, 10);
            g2d.setColor(Color.black);
            g2d.fillArc(5, 50, 10, 10, 0, 360);
            g2d.fillArc(55, 50, 10, 10, 0, 360);

            g2d.setColor(Color.gray);
            g2d.fillRect(0, 10, 70, 45);
            g2d.setColor(Color.yellow);
            g2d.fillRoundRect(50, 15, 35, 35, 10, 10);
            g2d.setColor(Color.black);
            g2d.fillArc(5, 50, 10, 10, 0, 360);
            g2d.fillArc(55, 50, 10, 10, 0, 360);
        }
    }

}

另一种选择可能是拥有多个卡车实例，因此当第二个卡车开始离开可见区域时，您可以创建另一个卡车

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.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

    public Test() {
        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 List<Truck> trucks;

        public TestPane() {
            trucks = new ArrayList<>(2);
            trucks.add(new Truck());
            Timer timer = new Timer(40, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    Truck[] truckArray = trucks.toArray(new Truck[trucks.size()]);
                    for (Truck truck : truckArray) {
                        truck.update(getSize());
                        if (truck.getX() > getWidth()) {
                            trucks.remove(truck);
                        } else if (truck.getX() + truck.getWidth() > getWidth() && trucks.size() == 1) {
                            trucks.add(new Truck());
                        }
                    }
                    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();
            for (Truck truck : trucks) {
                truck.paint(g2d);
            }
            g2d.dispose();
        }

    }

    public class Truck {

        // I had to calculate these
        private int width = 85;
        private int height = 65;

        private int x = -width;
        private int y;

        private int xDelta = 4;

        public void update(Dimension bounds) {
            x += xDelta;
        }

        public int getX() {
            return x;
        }

        public int getY() {
            return y;
        }

        public int getWidth() {
            return width;
        }

        public int getHeight() {
            return height;
        }

        public void paint(Graphics2D g) {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.translate(x, y);
            paintTruck(g2d);
            g2d.dispose();
        }

        protected void paintTruck(Graphics2D g2d) {
            g2d.setColor(Color.gray);
            g2d.fillRect(0, 10, 70, 45);
            g2d.setColor(Color.yellow);
            g2d.fillRoundRect(50, 15, 35, 35, 10, 10);
            g2d.setColor(Color.black);
            g2d.fillArc(5, 50, 10, 10, 0, 360);
            g2d.fillArc(55, 50, 10, 10, 0, 360);

            g2d.setColor(Color.gray);
            g2d.fillRect(0, 10, 70, 45);
            g2d.setColor(Color.yellow);
            g2d.fillRoundRect(50, 15, 35, 35, 10, 10);
            g2d.setColor(Color.black);
            g2d.fillArc(5, 50, 10, 10, 0, 360);
            g2d.fillArc(55, 50, 10, 10, 0, 360);
        }
    }

}