延迟在java图形中不起作用

这是通过Bresenham算法在计算位置上绘制点的代码：

public void drawBresenhamPoints(Graphics2D g2, List<Point> bresenham) throws InterruptedException
{
       Graphics2D g = (Graphics2D) g2;

    if(bresenham == null)
        return;

    g.setColor(Color.DARK_GRAY);

    for(int i = 0; i < bresenham.size(); i = i+20)
    {
        int x = bresenham.get(i).x - pointWidth1/2;
        int y = bresenham.get(i).y - pointWidth1/2;

        int ovalW = pointWidth1;
        int ovalH = pointWidth1;

        g.fillOval(x, y, ovalW, ovalH);

            // delay
         try 
         {
             Thread.sleep(10);
         } 
         catch(Throwable e) 
         {
         System.out.println(e.getMessage()); 
         }
    }
}

列表’bresenham’包含在Bresenham的线绘制算法的帮助下预先计算的所有点.我想在’for’循环内设置1秒的延迟,以便在1秒的间隔后绘制每个点. “延迟”部分中列出的部分不起作用.如何让’延迟’工作？
    更具体地说,我希望在1秒的间隔内看到屏幕上逐一绘制的所有点.

解决方法:

我假设您在paint / paintComponent方法中调用此方法.

只是一个指针：从来没有睡过油漆过程

而是使用javax.swing.Timer重复任务.我要做的是

>有两个列表.你的清单< Point> bresenham和另一个List< Point> paintList. bresenham将保存您的数据,paintList最初将为空.
>使用paintList绘制您的点

@override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D)g;

    for (Point p : paintList) {
        int x = bresenham.get(i).x - pointWidth1/2;
        int y = bresenham.get(i).y - pointWidth1/2;

        int ovalW = pointWidth1;
        int ovalH = pointWidth1;

        g.fillOval(x, y, ovalW, ovalH);
    }
}

>虽然最初在paintList中没有任何内容,但每次触发计时器事件时,都会向列表中添加一个新Point.

Timer timer = new Timer(100, new ActionListener(){
    @Override
    public void actionPerformed(ActionEvent e) {
        if (bresenham.isEmpty()) {
            ((Timer)e.getSource()).stop();
        } else {
            paintList.add(bresemham.get(0));
            bresenham.remove(0);
        }
        repaint();  
    }
});
timer.start();

构造函数的基本计时器是第一个延迟,即“迭代”之间延迟的时间,以及实际侦听每延迟毫秒触发的计时器事件的侦听器中的第二个参数.那么上面代码基本上做的是将一个Point添加到从bresenham列表中获取的paintList,然后删除调用paintComponent的重绘项.当列表为空时,计时器将停止.

UPDATE

这是一个完整的运行示例

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.Timer;

public class BresenhamPoints extends JPanel {

    private static final int D_W = 500;
    private static final int D_H = 500;

    private List<Point> bresenhamList;
    private List<Point> paintList;

    public BresenhamPoints() {
        bresenhamList = createRandomPoints();
        paintList = new ArrayList<>();

        Timer timer = new Timer(100, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (bresenhamList.isEmpty()) {
                    ((Timer) e.getSource()).stop();
                } else {
                    paintList.add(bresenhamList.get(0));
                    bresenhamList.remove(0);
                }
                repaint();
            }
        });
        timer.start();
    }

    private List<Point> createRandomPoints() {
        Random rand = new Random();
        List<Point> list = new ArrayList<>();
        for (int i = 0; i < 100; i++) {
            list.add(new Point(rand.nextInt(D_H), rand.nextInt(D_H)));
        }
        return list;
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        for (Point p : paintList) {
            g.fillOval(p.x - 5, p.y - 5, 10, 10);
        }
    }

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

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new BresenhamPoints());
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
}

标签：thread-sleep,paintcomponent,java,animation,swing
来源： https://codeday.me/bug/20190929/1832371.html