OnJava8-Examples/ui/SineWave.java

// ui/SineWave.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
// Drawing with Swing, using a JSlider.
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import static onjava.SwingConsole.*;

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

public class SineWave extends JFrame {
  private SineDraw sines = new SineDraw();
  private JSlider adjustCycles = new JSlider(1, 30, 5);
  public SineWave() {
    add(sines);
    adjustCycles.addChangeListener(e -> sines.setCycles(
      ((JSlider)e.getSource()).getValue()));
    add(BorderLayout.SOUTH, adjustCycles);
  }
  public static void main(String[] args) {
    run(new SineWave(), 700, 400);
  }
}