import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*; 

public class LissajousPlotPanel extends JPanel {

    double [] X, Y;
    double a, b;
    double xLo,  xHi,  yLo,  yHi, tickInterval;
    
    public void paintComponent(Graphics g) {


	g.setFont( new Font( "SansSerif", Font.BOLD, 12 ) );
	super.paintComponent(g);   //otherwise add to existing grid
	//seems to have no effect???  i.e. always cleared
	
	int w=getWidth();     //panel size
	int h=getHeight();    
	double xWidth = xHi - xLo;   //user grid size
	double yHeight = yHi - yLo;
	double xScale = w / xWidth;   //scale user to panel
	double yScale = h / yHeight;
	double xOffset = xLo * xScale;
	double yOffset = yLo * yScale;
        DecimalFormat d3;
	d3 = new DecimalFormat ("0.000");

	g.setColor(Color.WHITE);
	g.fillRect(0,0,w,h);

	g.setColor(Color.BLACK);
	
	int xAxis = (int)(h+yOffset);
	int yAxis = (int)(-xOffset);
	//g.drawLine(0,xAxis,w,xAxis );   //x axis
	//g.drawLine(yAxis,0,yAxis,h);    //y axis

	/*for (double tick=tickInterval; tick<=xHi; tick+=tickInterval) {
	    g.setColor(Color.LIGHT_GRAY);
	    g.drawLine((int)(tick * xScale - xOffset),0,(int)(tick * xScale - xOffset),h);
	    g.setColor(Color.BLACK);
	    g.drawLine((int)(tick * xScale - xOffset),xAxis-3,(int)(tick * xScale - xOffset),xAxis+3);
	}
	for (double tick=-tickInterval; tick>=xLo; tick-=tickInterval) {
	    g.setColor(Color.LIGHT_GRAY);
	    g.drawLine((int)(tick * xScale - xOffset),0,(int)(tick * xScale - xOffset),h);
	    g.setColor(Color.BLACK);
	    g.drawLine((int)(tick * xScale - xOffset),xAxis-3,(int)(tick * xScale - xOffset),xAxis+3);
	}
	for (double tick=tickInterval; tick<=yHi; tick+=tickInterval) {
	    g.setColor(Color.LIGHT_GRAY);
	    g.drawLine(0,h-(int)(tick * yScale - yOffset), w,h-(int)(tick * yScale - yOffset));
	    g.setColor(Color.BLACK);
	    g.drawLine(yAxis-3,h-(int)(tick * yScale - yOffset),yAxis+3,h-(int)(tick * yScale - yOffset));
	}
	for (double tick=-tickInterval; tick>=yLo; tick-=tickInterval) {
	    g.setColor(Color.LIGHT_GRAY);
	    g.drawLine(0,h-(int)(tick * yScale - yOffset), w,h-(int)(tick * yScale - yOffset));
	    g.setColor(Color.BLACK);
	    g.drawLine(yAxis-3,h-(int)(tick * yScale - yOffset),yAxis+3,h-(int)(tick * yScale - yOffset));
	}
        */
	int x, y, x2, y2;

	//g.setColor(Color.RED);
	g.setColor(Color.BLACK);
	    x = (int)(X[0] * xScale - xOffset);
	    y = h - (int)(Y[0] * yScale - yOffset);
	for (int i=1; i<X.length; i++) {
	    x2 = (int)(X[i] * xScale - xOffset);
	    y2 = h - (int)(Y[i] * yScale - yOffset);
	    g.drawLine(x,y,x2,y2);
	    //g.drawLine(x+1,y+1,x2+1,y2+1);  //doublewidth line
	    x = x2;
	    y = y2;
	    //g.fillRect(x-1,y-1,2,2);
	}
    }
    
    public void newPlot(double[] X, double[] Y, double a, double b,
    	                double xLo, double xHi, double yLo, double yHi, double tickInterval) {

	this.xLo = xLo;
	this.xHi = xHi;
	this.a = a;
	this.b = b;
	this.yLo = yLo;
	this.yHi = yHi;
	this.tickInterval = tickInterval;
	this.X = X;
	this.Y = Y;
	repaint();    
    }

    //not good.  repaint clears ??
    public void addPlot(double[] X, double[] Y) {

	this.X = X;
	this.Y = Y;
	repaint();    
    }

}