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

abstract class Chart extends JPanel {
    int[]  data;
    int    width, height;
    int    margin = 20; //a margin of blank space around the chart
    Color  fgColor = Color.black;
    Color  bgColor = Color.white;

    public Chart(int[] thedata) {
	data = new int[thedata.length];
	System.arraycopy(thedata,0,data,0,data.length);

    }

    public void setData(int[] thedata) {
	data = new int[thedata.length];
	System.arraycopy(thedata,0,data,0,data.length);
    }

    public void setBackground(Color color) { bgColor = color; }

    public void setForeground(Color color) { fgColor = color; }

    public void setMargin(int newMargin) { margin = newMargin; }

    public void paintComponent(Graphics g) {
	Graphics2D g2 = (Graphics2D) g;
	g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
			    RenderingHints.VALUE_ANTIALIAS_ON );

	width  = getWidth();
	height = getHeight();

	g2.setBackground(bgColor);
	g2.clearRect(0,0,width,height);

	width  -= 2*margin;
	height -= 2*margin;

	g2.translate(margin,margin);

	g2.setColor(fgColor);
	draw(g);
    }

    abstract public void draw(Graphics g);

}