java - 消除滚动文本的闪烁/抖动

Question

我终于制作了一个可以按照我想要的方式运行的股票代码，但现在唯一的问题是它看起来有点不稳定，看起来像是在旧电视上显示的。如何让它看起来更平滑？

这是我的代码:

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;

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

public class Scroll1 extends JPanel{
    private int x;
    private int x2;
    private int y;
    private int width;
    private String text;
    private Font f=(new Font("SansSerif", Font.PLAIN,24));
    public Scroll1(int startX)
    {
        x=Integer.MIN_VALUE;
        x2=Integer.MIN_VALUE;
        y=150;
        text= "We are pleased to announce that Actavis has completed the acquisition of Auden Mckenzie, a dynamic and fast growing company focused on the development, licensing and marketing of generic medicines and proprietary brands in the UK.  ";
    }
    @Override
    public void paintComponent(Graphics g)
    {
            g.setFont(f);
          if ( x == Integer.MIN_VALUE ){
              width=g.getFontMetrics().stringWidth(text);
                x = 0;

            }
          if ( x2 == Integer.MIN_VALUE ){
                x2 = g.getFontMetrics().stringWidth(text);
            }
        g.setColor(Color.white);

        g.fillRect(this.getX(), this.getY(), (int)this.getBounds().getWidth(), (int)this.getBounds().getHeight());
        g.setColor(Color.black);
        g.drawString(text, x, y);
        g.drawString(text, x2, y);
    }

    public void start() throws InterruptedException{
        while(true){
            while(x>= (-width)&&x2!=Integer.MIN_VALUE){
                x--;
                x2--;
                y = getHeight()/2;
                Thread.sleep(15);
                this.
                validate();
                repaint();
                if(x2<=-width)
                {
                    x2=width;
                }
            }

            if(x<-width&&x!=Integer.MIN_VALUE)
            {
                x=width;    
            }
        }
    }
    public static void main(String[] args) {
        JFrame frame = new JFrame("Scrolling Panel");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Scroll1 scrolling = new Scroll1(-100);

        frame.getContentPane().add(scrolling);
        frame.setSize(400, 300);
        frame.setVisible(true);
        try {
            scrolling.start();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

Answer 1

1. 调用 super.paintComponent在进行自定义绘画之前
2. 更喜欢 Swing Timer的Thread ，如 Swing Timers在 EDT 内触发，并且您在 paintComponent 之间进行脏读的风险较小。方法和 Thread
3. paintComponent实际上不应该对渲染状态做出决定，而应该只绘制当前状态。
4. 您不需要g.fillRect(this.getX(), this.getY(), (int) this.getBounds().getWidth(), (int) this.getBounds().getHeight()); ，只需设置面板的背景颜色并让绘画例程完成其工作。绘画是从 0x0 完成的，是组件的左上角
5. 您的 while 有问题在你的 start 中循环方法似乎不允许它运行(至少在我的测试中)

Can you help me try to transfer it over to a swing timer or give me a good source to do so?

你能付钱给我吗？ ;)

首先，让它完全“错开”是不可能的，因为该过程依赖于系统与您的请求保持同步的能力。例如，您确实不需要它以 > 60 fps 运行，说真的，25 fps 甚至 15 fps 会更适合您想要做的事情。您可以通过使用移动增量来控制滚动速度

以下示例使用 Swing Timer ，就像我之前的示例一样，但此示例还将创建一个“连续”循环，其中如果显示的文本量小于可见区域的宽度，它将添加一条"new"消息来跟踪它。

这个例子能够显示多个不同长度的不同消息，但我想，这是一个额外的好处

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
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 Scroll1 extends JPanel {

    private String text;
    private Font f = (new Font("SansSerif", Font.PLAIN, 24));

    private List<TickerTap> tickerTaps;

    public Scroll1(int startX) {
        text = "We are pleased to announce that Actavis has completed the acquisition of Auden Mckenzie, a dynamic and fast growing company focused on the development, licensing and marketing of generic medicines and proprietary brands in the UK.";
        setFont(f);
        setBackground(Color.WHITE);
        tickerTaps = new ArrayList<>(4);

        Timer timer = new Timer(40, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                FontMetrics fm = getFontMetrics(getFont());
                if (tickerTaps.isEmpty()) {
                    tickerTaps.add(new TickerTap(text, getWidth()));
                }

                TickerTap taps[] = tickerTaps.toArray(new TickerTap[tickerTaps.size()]);
                int visibleWidth = 0;
                for (TickerTap tap : taps) {
                    tap.move();
                    int messageWidth = fm.stringWidth(tap.getMessage());
                    if (tap.getxPos() <= -messageWidth) {
                        tickerTaps.remove(tap);
                    } else {
                        visibleWidth += tap.getxPos() + messageWidth;
                    }
                }

                while (visibleWidth < getWidth()) {
                    TickerTap last = tickerTaps.get(tickerTaps.size() - 1);
                    int xPos = last.getxPos() + fm.stringWidth(last.getMessage());
                    String message = " * " + text;
                    TickerTap next = new TickerTap(message, xPos);
                    visibleWidth += next.getxPos() + fm.stringWidth(next.getMessage());
                    tickerTaps.add(next);
                }

                repaint();
            }
        });
        timer.start();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
        g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
        g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
        g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
        g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
        g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);

        for (TickerTap tap : tickerTaps) {
            FontMetrics fm = g2d.getFontMetrics();
            int y = ((getHeight() - fm.getHeight()) / 2) + fm.getAscent();
            g2d.setColor(Color.black);
            g2d.drawString(tap.getMessage(), tap.getxPos(), y);
        }
    }

    public class TickerTap {

        private String message;
        private int xPos;

        public TickerTap(String message, int xPos) {
            this.message = message;
            this.xPos = xPos;
        }

        public String getMessage() {
            return message;
        }

        public int getxPos() {
            return xPos;
        }

        public void move() {
            xPos -= 2;
        }
    }

    public static void main(String[] args) {
        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("Scrolling Panel");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                Scroll1 scrolling = new Scroll1(-100);

                frame.getContentPane().add(scrolling);
                frame.setSize(400, 300);
                frame.setVisible(true);
            }
        });
    }
}

看看How to use Swing Timers更多细节。 Timer如果你简单地把它想象成一种循环，实际上真的很容易理解