import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;

public class GraphDraw1 extends Applet implements AdjustmentListener {

    
     private Scrollbar aScrollbar, bScrollbar, cScrollbar, dScrollbar;
     private final int xPixelStart = 10, xPixelEnd = 410, xOrigin = 215;
     private final int yPixelStart = 10, yPixelEnd = 410, yOrigin = 215;
     private final float xStart = -5.0f, xEnd = 5.0f;
     private final float yStart = -5.0f, yEnd = 5.0f;
     private final float scale = (xPixelEnd - xPixelStart)/(xEnd - xStart);

     private float a, b, c, d;

     public void init() {
	     Label aLabel = new Label("a:", Label.RIGHT);
	     add(aLabel);
	     aScrollbar = new Scrollbar(Scrollbar.HORIZONTAL,50, 10, 0, 100);
  	   add(aScrollbar);
  	   aScrollbar.addAdjustmentListener(this);
  	   Label bLabel = new Label("b:", Label.RIGHT);
  	   add(bLabel);
  	   bScrollbar = new Scrollbar(Scrollbar.HORIZONTAL, 50, 10, 0, 100);
  	   add(bScrollbar);
  	   bScrollbar.addAdjustmentListener(this);
  	   Label cLabel = new Label("c:", Label.RIGHT);
  	   add(cLabel);
  	   cScrollbar = new Scrollbar(Scrollbar.HORIZONTAL,50, 10, 0, 100);
  	   add(cScrollbar);
  	   cScrollbar.addAdjustmentListener(this);
  	   Label dLabel = new Label("d:", Label.RIGHT);
  	   add(dLabel);
  	   dScrollbar = new Scrollbar(Scrollbar.HORIZONTAL,50, 10, 0, 100);
  	   add(dScrollbar);
  	   dScrollbar.addAdjustmentListener(this);
     }

     public void adjustmentValueChanged(AdjustmentEvent event) {
  	  int aValue = aScrollbar.getValue();
  	  int bValue = bScrollbar.getValue();
  	  int cValue = cScrollbar.getValue();
  	  int dValue = dScrollbar.getValue();
  	  setParameters(aValue, bValue, cValue, dValue);
  	  repaint();
     }

     public void paint(Graphics g) {
	     draw(g);
     }



     private float theFunction(float x, float a, float b, float c, float d){
	     return(a*x*x*x + b*x*x + c*x + d);
     }

     private float scaleX(int xPixel){
	     float value = (xPixel - xOrigin)/scale;
	     return value;
     }

     private int scaleY(float y){
	     int pixelCoord;
	     pixelCoord = Math.round(-y*scale) + yOrigin;
	     return pixelCoord;
     }

     public void setParameters(
	                   int aValue, int bValue, int cValue, int dValue) {
  	   a=scale(aValue);
  	   b=scale(bValue);
  	   c=scale(cValue);
  	   d=scale(dValue);
     }

     private float scale(int coefficient){
	     return((coefficient - 50)/10.0f);
     }

     public void draw(Graphics g){
	     float x, y, nextX, nextY;
	     int xPixel, yPixel, nextXPixel, nextYPixel;

	     g.drawString("a= "+a+" b= "+b+" c= "+c+" d= "+d, 30, 60);

       for(xPixel = xPixelStart; xPixel < xPixelEnd; xPixel++){
  	      x = scaleX(xPixel);
  	      y = theFunction(x, a, b, c, d);
  	      yPixel = scaleY(y);
  	      nextXPixel = xPixel + 1;

  	      nextX = scaleX(nextXPixel);
  	      nextY = theFunction(nextX, a, b, c, d);
  	      nextYPixel = scaleY(nextY);

  	      g.drawLine(xPixel, yPixel, nextXPixel, nextYPixel);
  	   }
     }
}