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

/* Animation of the really simple "test each pixel to see if it is in the
   polygon" algorithm for drawing filled polygons. */
public class poly extends BigPixelApplet{
  
    public void init() {
	super.init();
	canvas.addMouseListener(new MyAdapter());
	canvas.addMouseMotionListener(new RubberLine());
    }
  
    Polygon p = new Polygon(); //polygon that is being created interactively
    boolean creating = false;  //have we started the polygon yet?
    int startx, starty;  //start of rubber line
    int endx, endy;      //end of rubber line

    public void run() {
	drawPolygon(p);
    }
  
    /** Implements a rubber band line that follows cursor while button is down */  class RubberLine extends MouseMotionAdapter {
	public void mouseDragged(MouseEvent e) {
	    Graphics g = canvas.getGraphics();
	    g.setXORMode(Color.cyan);
	    g.drawLine(toScreenX(startx),toScreenY(starty),toScreenX(endx),toScreenY(endy));
	    endx = fromScreenX(e.getX());
	    endy = fromScreenY(e.getY());
	    g.drawLine(toScreenX(startx),toScreenY(starty),toScreenX(endx),toScreenY(endy));
	}
	public void mouseMoved(MouseEvent e) {
	    if (creating) {
		mouseDragged(e);
	    }
	}
    }

    class MyAdapter extends MouseAdapter {
	public void mousePressed(MouseEvent e) {
	    startx = fromScreenX(e.getX());
	    starty = fromScreenY(e.getY());
	    endx = startx;
	    endy = starty;
	    if (startx == p.xpoints[0] && starty == p.ypoints[0]){ //polygon closed
		creating = false;
		canvas.setPolygon(p);
		begin();//this calls run() in another thread to do the animation
	    } else {
		if (!creating) {
		    creating = true;
		    p = new Polygon();
		}
		p.addPoint(startx, starty);
	    }
	}
    }

    /* These three variables contain the state of the algorithm */
    int x;
    int y;
    int count;
    public String showState() {
	return "x = " + x + " y = " + y + " count = " + count;
    }

    void drawPolygon(Polygon p){
	//create array of all the edges
	Edge[] edges = new Edge[p.npoints];
	edges[0] = new Edge(p.xpoints[p.npoints-1],p.ypoints[p.npoints-1],p.xpoints[0],p.ypoints[0]);
	for (int i = 1; i < p.npoints; i++) {
	    edges[i] = new Edge(p.xpoints[i-1],p.ypoints[i-1],p.xpoints[i],p.ypoints[i]);
	}
    
	Rectangle r = p.getBounds();
	for (y = r.y; y < r.y + r.height; y++) {
	    for (x = r.x; x < r.x + r.width; x++) {
		count = 0;
		for (int i = 0; i < p.npoints; i++) {
		    if (edges[i].rayIntersect(x,y)) count++;
		}
		if (count % 2 == 1) {
		    drawPixel(x,y);
		}
		if (step()) return;
	    }
	}
      
    }
  
}