种子填充实例运行出问题

import java.awt.*;

import java.applet.*;

import java.awt.image.ImageProducer;

import java.awt.image.MemoryImageSource;

import java.util.Stack;

public class scanseed extends Applet {

private static final long serialVersionUID = 1L;

int red=Color.red.getRGB();

int blue=Color.red.getRGB();

int black=Color.red.getRGB();

int  y,ymax,ymin,w=200,h=200;

Image image;

int  pixels[]=new int[w*h];

double x;

double dy,dx;

Point []p=new Point[10];

public void init()

{

p[0] = new Point(15, 15);

p[5] = new Point(145, 35);

p[4] = new Point(145, 95);

p[3] = new Point(115, 115);

p[2] = new Point(65, 115);

p[1] = new Point(15, 75);

p[6] = new Point(85, 65);

p[7]=p[0];

Point q=new Point(4,6);

boundary();

scan(pixels,q,black,blue,red);

ImageProducer ip=new MemoryImageSource(w,h,pixels,0,w);

image=createImage(ip);

}

public void boundary()

{

for(int i=0;i<7;i++)

{

dy=p[i+1].y-p[i].y;

if(dy!=0){

dx=(p[i+1].x-p[i].x)/dy;}

if(dy>0) x=p[i].x;

else  x=p[i+1].x;

ymax=(Math.max(p[i].y,p[i+1].y));

ymin=(Math.min(p[i].y,p[i+1].y));

for(y=ymin+1;y<=ymax;y++)

{

x=x+dx;

if(pixels[y*w+(int)(x+0.5)]==red)

pixels[y*w+(int)(x+0.5)+1]=red;//保证是偶数

else

pixels[y*w+(int)(x+0.5)]=red;

}

}

}

public void scan(int[]pixels,Point point,int old_color,int new_color,int boundary_color) {

int x,y,savex,xright,xleft;

Point p;

Stack stack=new Stack();

stack.push(point);

boolean span_need_fill;

while(!stack.empty()) {

p=(Point)(stack.pop());

x=p.x;

y=p.y;

savex=x;

while(pixels[y*w+x]!=boundary_color) {

pixels[y*w+x]=new_color;

x++;

}

xright=x-1;

x=savex-1;

while(pixels[y*w+x]!=boundary_color) {

pixels[y*w+x]=new_color;

x--;

}

xleft=x+1;

x=xleft;

y=y+1;

while(x<=xright) {

span_need_fill=false;

while(pixels[w*y+x]==old_color&&x<=xright) {

span_need_fill=true;

x++;

}

if(span_need_fill) {

p=new Point(x-1,y);

stack.push(p);

span_need_fill=false;

}

while(pixels[y*w+x]!=old_color&&x<=xright)x++;

}

x=xleft;

y=y-2;

while(x<=xright) {

span_need_fill=false;

while(pixels[w*y+x]==old_color) {

span_need_fill=true;

x++;

}

if(span_need_fill) {

p=new Point(x-1,y);

stack.push(p);

span_need_fill=false;

}

while(pixels[y*w+x]!=old_color&&x<=xright)x++;

}

}

}

public void paint(Graphics g)

{

g.drawImage(image, 0, 0, null);

}

}