Java Swing 中的跑马灯效果

Question

如何在Java Swing中实现跑马灯效果

Answer 1

下面是一个使用 javax.swing.Timer 的示例。

import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;

/** @see http://stackoverflow.com/questions/3617326 */
public class MarqueeTest {

    private void display() {
        JFrame f = new JFrame("MarqueeTest");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        String s = "Tomorrow, and tomorrow, and tomorrow, "
        + "creeps in this petty pace from day to day, "
        + "to the last syllable of recorded time; ... "
        + "It is a tale told by an idiot, full of "
        + "sound and fury signifying nothing.";
        MarqueePanel mp = new MarqueePanel(s, 32);
        f.add(mp);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
        mp.start();
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new MarqueeTest().display();
            }
        });
    }
}

/** Side-scroll n characters of s. */
class MarqueePanel extends JPanel implements ActionListener {

    private static final int RATE = 12;
    private final Timer timer = new Timer(1000 / RATE, this);
    private final JLabel label = new JLabel();
    private final String s;
    private final int n;
    private int index;

    public MarqueePanel(String s, int n) {
        if (s == null || n < 1) {
            throw new IllegalArgumentException("Null string or n < 1");
        }
        StringBuilder sb = new StringBuilder(n);
        for (int i = 0; i < n; i++) {
            sb.append(' ');
        }
        this.s = sb + s + sb;
        this.n = n;
        label.setFont(new Font("Serif", Font.ITALIC, 36));
        label.setText(sb.toString());
        this.add(label);
    }

    public void start() {
        timer.start();
    }

    public void stop() {
        timer.stop();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        index++;
        if (index > s.length() - n) {
            index = 0;
        }
        label.setText(s.substring(index, index + n));
    }
}

Answer 2

我知道这是一个迟到的答案，但我刚刚看到另一个关于已关闭的字幕的问题，因为它被认为是该答案的重复。

所以我想我应该添加我的建议，该建议采用与此处建议的其他答案不同的方法。

MarqueePanel 滚动面板上的组件，而不仅仅是文本。因此，这使您可以充分利用任何 Swing 组件。通过添加带有文本的 JLabel 可以使用简单的选取框。更高级的选取框可能会使用带有 HTML 的 JLabel，这样您就可以为文本使用不同的字体和颜色。您甚至可以添加带有图像的第二个组件。

Answer 3

基本答案是您将文本/图形绘制到位图中，然后实现一个以一定量绘制位图偏移的组件。通常选取框/滚动条向左滚动，因此偏移量增加，这意味着位图绘制在 -offset 处。您的组件运行一个定期触发的计时器，增加偏移量并使自身无效，以便重新绘制。

像包装这样的事情处理起来有点复杂，但相当简单。如果偏移量超过位图宽度，则将其重置回 0。如果偏移量 + 组件宽度 >位图宽度 您从位图的开头开始绘制组件的其余部分。

一个像样的股票行情指示器的关键是使滚动尽可能平滑且无闪烁。因此，可能有必要考虑对结果进行双缓冲，首先将滚动位绘制到位图中，然后一次性渲染它，而不是直接绘制到屏幕中。

Answer 4

下面是我整理的一些代码，供您入门。我通常会采用 ActionListener 代码并将其放入某种 MarqueeController 类中，以使此逻辑与面板分开，但这是关于组织 MVC 架构的不同问题，并且在一个足够简单的类中，例如这或许并不是那么重要。

还有各种动画库可以帮助您做到这一点，但我通常不喜欢将库包含到项目中只是为了解决这样的一个问题。

public class MarqueePanel extends JPanel {
  private JLabel textLabel;
  private int panelLocation;
  private ActionListener taskPerformer;
  private boolean isRunning = false;

  public static final int FRAMES_PER_SECOND = 24;
  public static final int MOVEMENT_PER_FRAME = 5;

  /**
   * Class constructor creates a marquee panel.
   */

  public MarqueePanel() {
    this.setLayout(null);
    this.textLabel = new JLabel("Scrolling Text Here");
    this.panelLocation = 0;
    this.taskPerformer = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
        MarqueePanel.this.tickAnimation();
      }
    }
  }

  /**
   * Starts the animation.
   */

  public void start() {
    this.isRunning = true;
    this.tickAnimation();
  }

  /**
   * Stops the animation.
   */

  public void stop() {
    this.isRunning = false;
  }

  /**
   * Moves the label one frame to the left.  If it's out of display range, move it back
   * to the right, out of display range.
   */

  private void tickAnimation() {
    this.panelLocation -= MarqueePanel.MOVEMENT_PER_FRAME;
    if (this.panelLocation < this.textLabel.getWidth())
      this.panelLocaton = this.getWidth();
    this.textLabel.setLocation(this.panelLocation, 0);
    this.repaint();
    if (this.isRunning) {
      Timer t = new Timer(1000 / MarqueePanel.FRAMES_PER_SECOND, this.taskPerformer);
      t.setRepeats(false);
      t.start();
    }
  }
}

Answer 5

将 JLabel 添加到框架或面板。

ScrollText s=   new ScrollText("ello Everyone.");
jLabel3.add(s);


public class ScrollText extends JComponent {
private BufferedImage image;

private Dimension imageSize;

private volatile int currOffset;

private Thread internalThread;

private volatile boolean noStopRequested;

public ScrollText(String text) {
currOffset = 0;
buildImage(text);

setMinimumSize(imageSize);
setPreferredSize(imageSize);
setMaximumSize(imageSize);
setSize(imageSize);

noStopRequested = true;
Runnable r = new Runnable() {
  public void run() {
    try {
      runWork();
    } catch (Exception x) {
      x.printStackTrace();
    }
  }
};

internalThread = new Thread(r, "ScrollText");
internalThread.start();
}

private void buildImage(String text) {
RenderingHints renderHints = new RenderingHints(
    RenderingHints.KEY_ANTIALIASING,
    RenderingHints.VALUE_ANTIALIAS_ON);

renderHints.put(RenderingHints.KEY_RENDERING,
    RenderingHints.VALUE_RENDER_QUALITY);

BufferedImage scratchImage = new BufferedImage(1, 1,
    BufferedImage.TYPE_INT_RGB);

Graphics2D scratchG2 = scratchImage.createGraphics();
scratchG2.setRenderingHints(renderHints);

Font font = new Font("Serif", Font.BOLD | Font.ITALIC, 24);

FontRenderContext frc = scratchG2.getFontRenderContext();
TextLayout tl = new TextLayout(text, font, frc);
Rectangle2D textBounds = tl.getBounds();
int textWidth = (int) Math.ceil(textBounds.getWidth());
int textHeight = (int) Math.ceil(textBounds.getHeight());

int horizontalPad = 600;
int verticalPad = 10;

imageSize = new Dimension(textWidth + horizontalPad, textHeight
    + verticalPad);

image = new BufferedImage(imageSize.width, imageSize.height,
    BufferedImage.TYPE_INT_RGB);

Graphics2D g2 = image.createGraphics();
g2.setRenderingHints(renderHints);

int baselineOffset = (verticalPad / 2) - ((int) textBounds.getY());

g2.setColor(Color.BLACK);
g2.fillRect(0, 0, imageSize.width, imageSize.height);

g2.setColor(Color.GREEN);
tl.draw(g2, 0, baselineOffset);

// Free-up resources right away, but keep "image" for
// animation.
scratchG2.dispose();
scratchImage.flush();
g2.dispose();
 }
public void paint(Graphics g) {
// Make sure to clip the edges, regardless of curr size
g.setClip(0, 0, imageSize.width, imageSize.height);

int localOffset = currOffset; // in case it changes
g.drawImage(image, -localOffset, 0, this);
g.drawImage(image, imageSize.width - localOffset, 0, this);

// draw outline
g.setColor(Color.black);
g.drawRect(0, 0, imageSize.width - 1, imageSize.height - 1);
  }
private void runWork() {
while (noStopRequested) {
  try {
    Thread.sleep(10); // 10 frames per second

    // adjust the scroll position
    currOffset = (currOffset + 1) % imageSize.width;

    // signal the event thread to call paint()
    repaint();
  } catch (InterruptedException x) {
    Thread.currentThread().interrupt();
  }
  }
 }

public void stopRequest() {
noStopRequested = false;
internalThread.interrupt();
}

public boolean isAlive() {
return internalThread.isAlive();
}


}

Answer 6

这应该是@camickr MarqueePanel 的改进。请参阅上文。

将鼠标事件映射到添加到 MarqueePanel 的特定组件

重写 MarqueePanel 的 add(Component comp) 以引导组件的所有鼠标事件

这里的问题是如何处理从单个组件激发的 MouseEvents成分。
我的方法是从添加的组件中删除鼠标侦听器，并让 MarqueePanel 将事件重定向到正确的组件。

就我而言，这些组件应该是链接。

    @Override
    public Component add(Component comp) {
        comp = super.add(comp);

        if(comp instanceof MouseListener)
             comp.removeMouseListener((MouseListener)comp);

        comp.addMouseListener(this);

        return comp;
    }

然后将组件x映射到MarqueePanel x，最后是正确的组件

@Override
public void mouseClicked(MouseEvent e)
{
    Component source = (Component)e.getSource();
    int x = source.getX() + e.getX();
    int y = source.getY();

    MarqueePanel2 marqueePanel = (MarqueePanel2) ((JComponent)e.getSource()).getParent();
    double x2 = marqueePanel.getWidth();
    double x1 = Math.abs(marqueePanel.scrollOffset);



    if(x >= x1 && x <= x2)
    {
        System.out.println("Bang " + x1);
        Component componentAt = getComponentAt(x+marqueePanel.scrollOffset, y);

        if(comp instanceof MouseListener)
             ((MouseListener) componentAt).mouseClicked(e);

        System.out.println(componentAt.getName());
    }
    else
    {
        return;
    }


    //System.out.println(x);
}