Help with graph applet code

Question

I cant figure out how to finsih this... I am creating an applet that draws a quadratic equation according to the parameters in the html file...
Here is the first class... I think its ok:
import java.awt.*;
import java.applet.*;
public class Graph extends Applet
     public void init()
         int in1 = Integer.parseInt(getParameter("a"));
         int in2 = Integer.parseInt(getParameter("b"));
         int in3 = Integer.parseInt(getParameter("c"));
          int a=1;
          int b=1;
          int c=1;
          if( in1!=0)
                                             a=in1;
          if( in2!=0)
             b=in2;
          if( in3!=0)
             c=in3;
          Dimension size = getSize();
          int width = size.width;
          String msg = "Quadratic Equation: y = ax^2 + bx + c";
          Label bottom = new Label(msg);
          Label header = new Label("Quadratic Equation");
          setLayout(new BorderLayout());
          GraphCanvas canvas = new GraphCanvas(width,a,b,c);
          add(header,BorderLayout.NORTH);
          add(canvas,BorderLayout.CENTER);
          add(bottom,BorderLayout.SOUTH);
}and here is the GraphCanvas class... which I can't figure out how to finish. hints and help would be appriciated:
import java.awt.*;
import java.applet.*;
public class GraphCanvas extends Canvas
     private double density;
     private final int XMAX = 10;
     private final int XMIN = -10;
    private final int YMAX = 10;
     private final int YMIN = -10;
     private double x;
     private double y;
     public GraphCanvas(int dimension, double a, double b, double c)
         dimension = 20;
          density=dimension/(XMAX-XMIN)
          y=a*x^2+b*x+c;
     public void paint(Graphics g)
          drawGrid(g);
          graphQuadratic(g);
     public void drawGrid(Graphics g)
     public void graphQuadratic(Graphics g)
          for (x=-10;x<=10;x+=0.02)
               y=x^2+x+1;
               moveTo(x,y);
               drawTo(g,x,y);
     public void moveto(double x, double y)
     public void drawto(double x, double y, Graphics g)
}it;s mainly the drawTo and moveTo methods that i am haveing trouble getting my tired mind wrapped around.

Answer 1

You may want to test the equation first, then save a "y-offset" value. Otherwise the images you draw may be off the canvas. Do this before drawing the scales (which I presume would appear in your drawGrid method), I'd suggest. Also use the offset when drawing the curve itself.
it;s mainly the drawTo and moveTo methods that i am haveing trouble getting my tired mind
wrapped around.Well, you're the one that wants to use them. What do you expect them to do?