使用计时器对Java线条图进行动画处理

制作动画时，有助于使用模型/视图/控制器模式。

这是我根据您的代码创建的GUI。

我简化了您的Ball课程。这就是定义一个球所需要的。

package twoBalls;

import java.awt.Color;
import java.awt.Point;

public class Ball {

    private final int radius;

    private final Color color;

    private final Point center;

    public Ball(int x, int y, int radius, Color color) {
        this(new Point(x, y), radius, color);
    }

    public Ball(Point center, int radius, Color color) {
        this.center = center;
        this.radius = radius;
        this.color = color;
    }

    public int getRadius() {
        return radius;
    }

    public Color getColor() {
        return color;
    }

    public Point getCenter() {
        return center;
    }

}

我创建了GUIModel类来保存您的GUI所需的所有信息。这会将模型与视图分开。

package twoBalls;

import java.awt.Point;
import java.util.ArrayList;
import java.util.List;

public class GUIModel {

    private double direction;
    private double distance;

    private List<Ball> balls;

    private Point lineStartPoint;
    private Point lineEndPoint;

    public GUIModel() {
        this.balls = new ArrayList<>();
    }

    public void addBall(Ball ball) {
        this.balls.add(ball);
    }

    public List<Ball> getBalls() {
        return balls;
    }

    public void calculatePoints() {
        this.lineStartPoint = balls.get(0).getCenter();
        this.lineEndPoint = balls.get(1).getCenter();

        this.distance = Point.distance(lineStartPoint.x, lineStartPoint.y,
                lineEndPoint.x, lineEndPoint.y);
        this.direction = Math.atan2(lineEndPoint.y - lineStartPoint.y,
                lineEndPoint.x - lineStartPoint.x);
    }

    public Point getCurrentPoint(int pos, int total) {
        double increment = distance / total;
        double length = increment * pos;

        double x = lineStartPoint.x + Math.cos(direction) * length;
        double y = lineStartPoint.y - Math.sin(direction) * length;

        x = Math.round(x);
        y = Math.round(y);

        return new Point((int) x, (int) y);
    }

    public Point getLineStartPoint() {
        return lineStartPoint;
    }

}

此类包含两个Ball实例，并计算线的长度和方向，分为总增量。

现在我们已经定义了模型类，让我们看一下视图类。第一个是您的Display类。

package twoBalls;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Display implements Runnable {

    private GUIModel guiModel;

    private JFrame frame;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Display());
    }

    public Display() {
        this.guiModel = new GUIModel();
        Ball ball1 = new Ball(150, 200, 50, Color.BLUE);
        Ball ball2 = new Ball(450, 200, 50, Color.GREEN);
        guiModel.addBall(ball1);
        guiModel.addBall(ball2);
        guiModel.calculatePoints();
    }

    @Override
    public void run() {
        frame = new JFrame();
        frame.setTitle("Show Balls Animation");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel();
        panel.setLayout(new BorderLayout());

        DrawingPanel drawingPanel = new DrawingPanel(guiModel);
        panel.add(drawingPanel, BorderLayout.CENTER);

        panel.add(createButtonPanel(drawingPanel), BorderLayout.SOUTH);

        frame.add(panel);

        frame.pack();
        frame.setVisible(true);
    }

    private JPanel createButtonPanel(DrawingPanel drawingPanel) {
        JPanel panel = new JPanel();

        JButton startButton = new JButton("Start Animation");
        startButton.addActionListener(new StartAnimation(drawingPanel));
        panel.add(startButton);

        return panel;
    }

    public class StartAnimation implements ActionListener {

        private DrawingPanel drawingPanel;

        public StartAnimation(DrawingPanel drawingPanel) {
            this.drawingPanel = drawingPanel;
        }

        @Override
        public void actionPerformed(ActionEvent event) {
            LineRunnable runnable = new LineRunnable(drawingPanel);
            new Thread(runnable).start();
        }

    }

}

Display类的构造函数建立了GUI模型。

Display类的run方法构造GUI，并启动动画。

看看我如何分离模型和视图。

StartAnimation类是您的控制器。当您左键单击JButton时，它将启动动画。稍后我将讨论LineRunnable类。

接下来，让我们看一下DrawingPanel类。

package twoBalls;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;

import javax.swing.JPanel;

public class DrawingPanel extends JPanel {

    private static final long serialVersionUID = -3709678584255542338L;

    private boolean drawLine;

    private int pos;
    private int total;

    private GUIModel guiModel;

    public DrawingPanel(GUIModel guiModel) {
        this.guiModel = guiModel;
        this.drawLine = false;
        this.setPreferredSize(new Dimension(600, 400));
    }

    public boolean isDrawLine() {
        return drawLine;
    }

    public void setDrawLine(boolean drawLine) {
        this.drawLine = drawLine;
    }

    public void setPos(int pos) {
        this.pos = pos;
        repaint();
    }

    public void setTotal(int total) {
        this.total = total;
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        Graphics2D g2d = (Graphics2D) g;

        for (Ball ball : guiModel.getBalls()) {
            g2d.setColor(ball.getColor());
            Point center = ball.getCenter();
            int radius = ball.getRadius();
            g2d.fillOval(center.x - radius, center.y - radius, radius + radius,
                    radius + radius);
        }

        if (isDrawLine()) {
            g2d.setColor(Color.BLACK);
            g2d.setStroke(new BasicStroke(5.0F));
            Point a = guiModel.getLineStartPoint();
            Point b = guiModel.getCurrentPoint(pos, total);
            g2d.drawLine(a.x, a.y, b.x, b.y);
        }
    }

}

该视图类唯一要做的就是绘制球和线。模型中负责计算线的长度。

我在这里设置首选大小，并在Display类中使用pack方法获取JFrame的大小。通常，您想知道绘图区域的尺寸，而不是整个窗口的尺寸。

最后，让我们看一下LineRunnable类。这是控制动画的类。

package twoBalls;

import java.awt.EventQueue;

public class LineRunnable implements Runnable {

    private int total;

    private DrawingPanel drawingPanel;

    public LineRunnable(DrawingPanel drawingPanel) {
        this.drawingPanel = drawingPanel;
        this.total = 240;
    }

    @Override
    public void run() {
        setDrawLine();
        for (int pos = 0; pos <= total; pos++) {
            setPos(pos);
            sleep(50L);
        }
    }

    private void setDrawLine() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                drawingPanel.setDrawLine(true);
                drawingPanel.setTotal(total);
            }
        });
    }

    private void setPos(final int pos) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                drawingPanel.setPos(pos);
            }
        });
    }

    private void sleep(long delay) {
        try {
            Thread.sleep(delay);
        } catch (InterruptedException e) {

        }
    }

}

在run方法中，我们将线划分为240个段，并每50毫秒绘制一个段。GUI需要12秒钟来绘制线条。您可以根据需要使用这些数字。

for循环是经典的动画循环。首先，您更新模型，这是我在绘图面板中所做的。那你睡吧

此动画循环在不同于GUI线程的线程上运行。这样可以使GUI保持响应状态。由于循环在不同的线程上运行，因此我们必须使用invokeLater方法在事件分发线程上进行绘制。

希望对您有帮助。分而治之。不要让一堂课做不止一件事情。