Swing and threads: scroll text : Swing Thread « Threads « Java

1. Java
2. Threads
3. Swing Thread

Swing and threads: scroll text

  

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;

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

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 = 10;
    int verticalPad = 6;

    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.white);
    g2.fillRect(0, 0, imageSize.width, imageSize.height);

    g2.setColor(Color.blue);
    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(100); // 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();
  }

  public static void main(String[] args) {
    ScrollText st = new ScrollText("Java can do animation!");

    JPanel p = new JPanel(new FlowLayout());
    p.add(st);

    JFrame f = new JFrame("ScrollText Demo");
    f.setContentPane(p);
    f.setSize(400, 100);
    f.setVisible(true);
  }
}

           
         
    
  

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