/* WaveApplet.java - mixes two sin waves */

import java.awt.*;

public class WaveApplet extends java.applet.Applet {
	//class variables
	float ratio;
	float offset;
	float length;
	float coeff;
	Button b1;
	Button b2;
	Choice c;
	TextField t;

	//initialise applet
	public void init() {
		setBackground(Color.green);
		ratio = (float).5;
		offset = (float)0;
		length = (float)5;
		coeff = (float)1;
		add(b1 = new Button("-"));
		add(b2 = new Button("+"));
		add(c = new Choice());
		c.addItem("ratio");
		c.addItem("offset");
		c.addItem("coeff");
		c.addItem("length");
		c.select(0);
		add("north", t = new TextField());
		updateText(ratio);
	}
 
	//write current value to textField
	public void updateText(float value) {
		String valString = new String();
		int val1, val2;
		val1 = (int)value;
		val2 = (int)((value - val1) * 100);
		valString = Integer.toString(val1) + "." + Integer.toString(val2);
		t.setText(valString);
	}
		
  	//return y value for given x value
	float f(float x) {
		return (float)(((1 - ratio) * Math.sin(x) + ratio * Math.sin(coeff * x + offset / 57.3)) * (size().height - 60)) / 2;
    	}

   	//draw the wave
	public void paint(Graphics g) {
		int y0, y1;
		float mid = (float)(size().height / 2);
		float step = (float)6.28 * length / (float)size().width;
		g.setColor(Color.black);
        	g.drawLine(0, (int)mid, size().width, (int)mid);
		for (int x = 0 ; x < size().width ; x++) {
			y0 = (int)(mid - f((float)x * step));
			y1 = (int)(mid - f((float)(x + 1) * step)); 
			g.setColor(Color.red);
	    		g.drawLine(x, y0, (x + 1), y1);
        	}
    	}
	
	public boolean action(Event e, Object o) {
		if (e.target == b1) {
			switch(c.getSelectedIndex()) {
				case 0:
					ratio -= (float).1;
					if (ratio < 0) ratio = 0;
					updateText(ratio);
				break;
				case 1:
					offset -= (float)15;
					if (offset < 0) offset = 0;
					updateText(offset); 
				break;
				case 2:
					coeff -= (float).5;
					if (coeff < 1) coeff = 1;
					updateText(coeff);
				break;
				case 3:		
					length -= 1;
					if (length < .5) length = (float).5;
					updateText(length);
				break;
			}	
			repaint();
			return true;
		}
		if (e.target == b2) {
			switch(c.getSelectedIndex()) {
				case 0:
					ratio += (float).1;
					if (ratio > 1) ratio = 1;
					updateText(ratio);
				break;
				case 1:
					offset += (float)15;
					if (offset > 1080) offset = 1080;
					updateText(offset); 
				break;
				case 2:
					coeff += (float).5;
					if (coeff > 10) coeff = 10;
					updateText(coeff);
				break;
				case 3:		
					length += 1;
					updateText(length);
				break;
			}	
			repaint();
			return true;
		}
		if (e.target == c) {
			switch(c.getSelectedIndex()) {
				case 0: 
					updateText(ratio);
				break;
				case 1: 
					updateText(offset);
				break;
				case 2:
					updateText(coeff);
				break;
				case 3: 
					updateText(length);
				break;
			}
			return true;
		}
		return super.action(e, o);
	}		
}