📄 sinewaveframe.html

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<html><head><title>Display page for SineWave at www.BruceEckel.com</title></head><FONT FACE="Verdana,Tahoma,Arial,Helvetica,Sans"><H2>SineWave.java</H2><hr></FONT>
<OBJECT classid="clsid:8AD9C840-044E-11D1-B3E9-00805F499D93"
    width="700" height="400" align="baseline"
    codebase="http://java.sun.com/products/plugin/1.2.2/jinstall-1_2_2-win.cab#Version=1,2,2,0">
<PARAM NAME="code" VALUE="SineWave.class">
<PARAM NAME="codebase" VALUE=".">
<PARAM NAME="type" VALUE="application/x-java-applet;version=1.2.2">
<COMMENT>
    <EMBED type="application/x-java-applet;version=1.2.2" 
       width="700" height="400" align="baseline" 
       code="SineWave.class" 
       codebase="."
       pluginspage="http://java.sun.com/products/plugin/1.2/plugin-install.html">
    <NOEMBED>
    </COMMENT>
       No Java 2 support for APPLET!!
    </NOEMBED></EMBED>
</OBJECT>
<FONT SIZE="+3"><PRE><B>
//: c13:SineWave.java
// From 'Thinking in Java, 2nd ed.' by Bruce Eckel
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
// Drawing with Swing, using a JSlider.
// &lt;applet code=SineWave
//  width=700 height=400&gt;&lt;/applet&gt;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import com.bruceeckel.swing.*;

class SineDraw extends JPanel {
  static final int SCALEFACTOR = 200;
  int cycles;
  int points;
  double[] sines;
  int[] pts;
  SineDraw() { setCycles(5); }
  public void setCycles(int newCycles) {
    cycles = newCycles;
    points = SCALEFACTOR * cycles * 2;
    sines = new double[points];
    pts = new int[points];
    for(int i = 0; i &lt; points; i++) {
      double radians = (Math.PI/SCALEFACTOR) * i;
      sines[i] = Math.sin(radians);
    }
    repaint();
  }    
  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    int maxWidth = getWidth();
    double hstep = (double)maxWidth/(double)points;
    int maxHeight = getHeight();
    for(int i = 0; i &lt; points; i++)
      pts[i] = (int)(sines[i] * maxHeight/2 * .95
                     + maxHeight/2);
    g.setColor(Color.red);
    for(int i = 1; i &lt; points; i++) {
      int x1 = (int)((i - 1) * hstep);
      int x2 = (int)(i * hstep);
      int y1 = pts[i-1];
      int y2 = pts[i];
      g.drawLine(x1, y1, x2, y2);
    }
  }
}

public class SineWave extends JApplet {
  SineDraw sines = new SineDraw();
  JSlider cycles = new JSlider(1, 30, 5);
  public void init() {
    Container cp = getContentPane();
    cp.add(sines);
    cycles.addChangeListener(new ChangeListener(){
      public void stateChanged(ChangeEvent e) {
        sines.setCycles(
          ((JSlider)e.getSource()).getValue());
      }
    });
    cp.add(BorderLayout.SOUTH, cycles);
  }
  public static void main(String[] args) {
    Console.run(new SineWave(), 700, 400);
  }
} ///:~
</B></PRE></FONT></body></html>
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