import java.awt.*;

/**
   Program: twoGraph35: graphs variable-frequency sine curves
   Purpose: demo of slider-driven updates in realtime
   @author: Paul Garrett, garrett@math.umn.edu
   @version: 1.22  30 December 1996
*/

public class twoGraph35 extends java.applet.Applet {

    int t; // the scrollbar's parameter

    float f;

    Scrollbar sb;

    public void init() {
	setLayout(new FlowLayout(FlowLayout.LEFT));
	sb = new Scrollbar(Scrollbar.HORIZONTAL,80,10,4,199);
	add(sb);
	t = 80;
    }

    public void paint(Graphics g) {

	g.drawString("Comparing graphs of sine functions", 10, 50);
	g.drawString("Move the slider to change", 20, 100);
	g.drawString("    the frequency and the", 20, 115);
	g.drawString("    constant in the formula", 20, 130);
	g.drawString(" - Paul Garrett", 20, 175);
	g.drawString("garrett@math.umn.edu", 30, 190);
	
	//g.drawLine(260,0,260,200);     // y-axis
	//g.drawLine(250,100,460,100);   // x-axis
	g.fillRect(260,0,2,200); // thick y-axis
	g.fillRect(250,100,210,2); // thick y-axis

	g.drawLine(260,0,256,7); // arrowheads on y-axis
	g.drawLine(260,0,264,7);
	g.drawString(" y ",243,10); // label y-axis

	g.drawLine(460,100,453,96); // arrowheads on x-axis
	g.drawLine(460,100,453,104);
	g.drawString(" x ",460,103); // label x-axis

	for (int i=10; i <= 190; i+=9) { // 10-pixel grid
	    g.drawLine(i+250,10,i+250,190); // vertical
	    g.drawLine(260,i,440,i); // horizontal
	}                              // done with grid...

    // upper left x, upper left y, width, height 

	g.fillRect(258, 98, 4,4); // blob at (0,0)

	g.fillRect(348, 98, 4,4); // blob at (1,0)
	g.fillRect(258, 8, 4,4); // blob at (0,1)

	g.fillRect(438, 98, 4,4); // blob at (2,0)
	g.fillRect(438, 8, 4,4); // blob at (2,1)

	g.fillRect(348, 98, 4,4); // blob at (1,1)
	g.fillRect(348, 8, 4,4); // blob at (1,1)

	g.fillRect(258, 188, 4,4); // blob at (0,-1)
	g.fillRect(348, 188, 4,4); // blob at (1,-1)
	g.fillRect(438, 188, 4,4); // blob at (2,-1)



	f = (float) 80/(float)t;

	g.drawString("y = sin("+f+" * x)",10,70);
	
	for (int i=-10; i < 205; i+=2) {
	    g.drawLine(i+250,
    (int)(100-90*Math.sin((float)(i-10)/t)),
    i+2+250,
    (int)(100-90*Math.sin(((float)(i-8))/t)));
	}
    }

    public boolean handleEvent(Event e) {
	
	if (e.target == sb && 
(e.id == Event.SCROLL_ABSOLUTE ||
e.id == Event.SCROLL_LINE_UP ||
e.id == Event.SCROLL_LINE_DOWN)) {
	    int v = ((Scrollbar)e.target).getValue();
	    t = sb.getValue();
            repaint();
	}
	return true;
    }

}