Aufgabe8_Grafik2D/src/aufgabe8_grafik2d/Zeiger.java

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package aufgabe8_grafik2d;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.Line2D;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import javax.swing.JComponent;

/**
 *
 * @author ahren
 */
public class Zeiger extends JComponent implements Runnable
{
  private static final float DICKE = 4f;
  private Line2D.Float linie;
  private BasicStroke stift;
  private volatile float radius;
  private volatile float minRadius;
  private volatile float maxRadius;
  private long schlafzeit;
  private ExecutorService eService;
  private Future task;
  
  public Zeiger(long schlafzeit)
  {
    this.schlafzeit = schlafzeit;
    linie = new Line2D.Float();
    stift = new BasicStroke(DICKE);
    radius = 100;
    minRadius = DICKE;
    eService = Executors.newSingleThreadExecutor();
    task = null;
  }

  @Override
  public void run()
  {
    float delta = 1f;
    while(true)
    {
      synchronized(this)
      {
        if (radius > maxRadius) delta = -1f;
        if (radius < minRadius) delta = +1f;
        radius += delta;
      }
      this.repaint();
      try
      {
        Thread.sleep(schlafzeit);
      }
      catch (Exception ex)
      {
        //lg.severe(ex.toString());
      }
    }
  }

  public void start()
  {
    if (task == null)
    {
      task = eService.submit(this);
    }
  }
  @Override
  public void paintComponent(Graphics g)
  {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D)g;
    
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                        RenderingHints.VALUE_ANTIALIAS_ON);
    
    float breite = this.getWidth() - 1;
    float hoehe = this.getHeight() - 1;
 
    synchronized(this)
    {
      maxRadius = -DICKE/2 + Math.min(breite, hoehe) / 2;
    }
    
    float x = breite/2 - radius;
    float y = hoehe/2 - radius;
    
    linie.setFrame(x, y, 2*radius, 2*radius);
    
    g2.setStroke(stift);
    g2.setPaint(Color.RED);
//    g2.fill(ellipse);
//    g2.setPaint(Color.BLACK);
    g2.draw(linie);
  }
  
}