//: 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. // <applet code=SineWave // width=700 height=400></applet> 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 < 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 < 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 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); } } ///:~