在Onpaint中画图闪现问题

 void CScreenDlg::OnPaint()

    
 {
    
 	CPaintDC dc(this); // device context for painting
    
 	// TODO: 在此处添加消息处理程序代码
    
 	// 不为绘图消息调用 CDialog::OnPaint()
    
 	//::MessageBox(NULL, "我在重绘", "" ,MB_OK);
    
 	//双缓存防止闪烁
    
 	          CWnd* hwnd = GetDlgItem(IDC_PIC);
    
 				  HDC hDesDC = hwnd->GetDC()->m_hDC;
    
 				  HDC hSrcDC = CreateCompatibleDC(hDesDC);
    
 				HBITMAP   hBitmap = (HBITMAP)LoadImage(AfxGetInstanceHandle(), strFilePath, IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE|LR_CREATEDIBSECTION);
    
 				BITMAP bm;
    
 				GetObject(hBit