int CMyDlg::scanline(int startX,int startY,int height, int width,int nWidth, BYTE *ScanImage)
{
    BYTE *Mark;
    Mark=ScanImage;
    int x,y,cur_x, cur_y,state = 0;
    int nHead=0, nTail=0,CurCount=0, MaxCount=0;
    CPoint curArea[1000],maxArea[1000]={0},temp[1000],Queue[1000];
    int QUEUECOUNT=height;
    for (y=startY;y<height-startY;y++)
    {
        for (x=startX;x<width-startX;x++)
        {
            if((ScanImage[y*nWidth+x]==0)&& (Mark[y * nWidth + x] == 0))
            {
                //1.进队
                Queue[nTail].x = x;
                Queue[nTail++].y = y;
                nTail = nTail % QUEUECOUNT;    
                Mark[y * nWidth + x] =1;
                if (nTail == nHead)
                {
                    return -1;
                }
                //2.出队
                while(nHead != nTail)
                {
                    //2.1 记录坐标
                    cur_x = Queue[nHead].x;
                    cur_y = Queue[nHead++].y;
                    nHead = nHead % QUEUECOUNT;
                      curArea[CurCount].x= cur_x;
                      curArea[CurCount++].y= cur_y;
                    //2.2 增加个数
                    //left 
                    if ((cur_x >= startX + 1) && 
                        (ScanImage[cur_y * nWidth + cur_x - 1] == 0)&& (Mark[cur_y * nWidth + cur_x - 1] == 0)) 
                        {
                        Queue[nTail].x= cur_x - 1;
                        Queue[nTail++].y= cur_y;
                        nTail = nTail % QUEUECOUNT;    
                        Mark[cur_y * nWidth + cur_x - 1] = 1;
                        if (nTail == nHead)
                        {
                            return -1;
                        }
                    }
                    //right
                    if ((cur_x < startX + nWidth - 1)&& 
                        (ScanImage[cur_y * nWidth + cur_x + 1] == 0)&& (Mark[cur_y * nWidth + cur_x + 1] == 0)) 
                    {
                        Queue[nTail].x = cur_x + 1;
                        Queue[nTail++].y = cur_y;
                        nTail = nTail % QUEUECOUNT;    
                        Mark[cur_y * nWidth + cur_x + 1] = 1;
                        if (nTail == nHead)
                        {
                            return -1;
                        }
                    }
                    //bottom       
                    if ((cur_y < startY + height - 1) && 
                        (ScanImage[(cur_y + 1)* nWidth + cur_x] ==0)&& (Mark[(cur_y + 1)* nWidth + cur_x] == 0))                         
                    {
                        Queue[nTail].x= cur_x;
                        Queue[nTail++].y = cur_y + 1;
                        nTail = nTail % QUEUECOUNT;    
                        Mark[(cur_y + 1)* nWidth + cur_x] = 1;
                        if (nTail == nHead)
                        {
                            return -1;
                        }
                    }
                    // top
                    if ((cur_y >=startY + 1)&& 
                        (ScanImage[(cur_y - 1)* nWidth + cur_x] ==0)&& (Mark[(cur_y - 1)* nWidth + cur_x] == 0))
                    {
                        Queue[nTail].x= cur_x;
                        Queue[nTail++].y= cur_y - 1;
                        nTail = nTail % QUEUECOUNT;
                        Mark[(cur_y - 1)* nWidth + cur_x] = 1;
                        if (nTail == nHead)
                        {
                            return -1;
                        }
                    }
                }
                //3. 判断当前最多
                if (CurCount > MaxCount)
                {
                    //交换数据
                    *temp = *maxArea;
                    *maxArea=*curArea;
                    *curArea=*temp;
                    MaxCount = CurCount; 
                    CurCount = 0;
                    state = 1;
                }
                else
                {
                    CurCount = 0;
                }        
            }            
        }
    }
    
    if(state == 0)
    {
        return 2;
    }
    //4.找到最大区域，将所有点变成灰色
    for (x = 0; x < MaxCount; x++)
    {
        ScanImage[maxArea[x].y * nWidth + maxArea[x].x] = 128;
    }
     

}