void CCrabDlg::OnPaint() 
{
	CPaintDC dc(this); // device context for painting
	COLORREF white= RGB(255,255,255);

	if(m_bDisplayData)
	{
		int x,y;
		for(int i=0,ii=0;i < m_nbytes && ii < m_nBlocks;i += 81,ii++)
		{
			for(int j=0,m=0;j < 9*m_iBlocksize;j += m_iBlocksize,m++) // row
			{
				for(int k=0,n=0;k < 9*m_iBlocksize;k += m_iBlocksize,n++) // col
				{
					x= m_cp.x+ii*9*m_iBlocksize+j;	
					y= m_cp.y+k;
					unsigned char ch= m_bdata[i+m*9+n];
					COLORREF color= RGB(ch,ch,ch);	// block gray level
					DrawBlock(&dc,x,y,m_iBlocksize,color);
				}
			}
		}
		m_bDisplayData= FALSE;
	}
	CDialog::OnPaint();
}

void CCrabDlg::DrawBlock(CDC* pdc,int bx,int by,int size,COLORREF color)
{
	for(int i=0;i < size;i++)
		for(int j=0;j < size;j++)
			pdc->SetPixel(bx+i,by+j,color);
}

BOOL CCrabDlg::ReadData(void)
{
	FILE * fi= fopen((LPCSTR)m_strInputFile,"rt");
	m_ndata=0;
	for(i=0;i < 2000;i++)
	{
		if(fscanf(fi,"%1d",&num) < 1)
			break;
		m_indata[i]= num;
		m_ndata++;
	}
	fclose(fi);
}

 unsigned char CCrabDlg::bits2byte(int *bits,int len)
 {
	 unsigned char bdata= 0;
	 unsigned char ch;
	 for(int i=0;i < len;i++)
	 {
		 if(bits[i]==1)
		 {
			 ch= 1;
			 ch= ch << i;
			 bdata |= ch;
		 }
	 }
	 return(bdata);
 }


void CCrabDlg::OnButtonDisplay() 
{
	int i,j;
	// flip the bits
	{
		for(i=0;i < m_ndata;i++) 
		{
			if(m_indata[i] == 0)
				m_dispdata[i]= 1;
			else
				m_dispdata[i]= 0;
		}
	}

	//encode the bits into bytes
	m_nbytes= 0;
	for(i=0,j=0;i < m_ndata;i += 8,j++)
	{
		m_bdata[j]= bits2byte(&m_dispdata[i],8);	
		m_nbytes++;
	}
	m_bDisplayData= TRUE;
	Invalidate();
}