mfc窗体透明方法

SetLayeredWindowAttributes（）:(详见MSDN)  
   
  BOOL   SetLayeredWindowAttributes(  
  HWND   hwnd,   //   handle   to   the   layered   window  
  COLORREF   crKey,   //   specifies   the   color   key  
  BYTE   bAlpha,   //   value   for   the   blend   function  
  DWORD   dwFlags   //   action  
  );  
  <Requirements>  
  Windows   NT/2000/XP:   Included   in   Windows   2000   and   later.  
  Windows   95/98/Me:   Unsupported.  
  Header:   Declared   in   Winuser.h;   include   Windows.h.  
  Library:   Use   User32.lib.  
   
  一些常量:    
  WS_EX_LAYERED   =   0x80000;  
  LWA_ALPHA   =   0x2;  
  LWA_COLORKEY=0x1    
  其中dwFlags有LWA_ALPHA和LWA_COLORKEY  
  LWA_ALPHA被设置的话,通过bAlpha决定透明度.  
  LWA_COLORKEY被设置的话,则指定被透明掉的颜色为crKey,其他颜色则正常显示.  
  注:要使使窗体拥有透明效果,首先要有WS_EX_LAYERED扩展属性(旧sdk也没有的).   
    
    
  在OnInitDialog()加入:  
  //加入WS_EX_LAYERED扩展属性  
  SetWindowLong(this->GetSafeHwnd(),GWL_EXSTYLE,  
  GetWindowLong(this->GetSafeHwnd(),GWL_EXSTYLE)^0x80000);  
  HINSTANCE   hInst   =   LoadLibrary("User32.DLL");    
  if(hInst)    
  {    
  typedef   BOOL   (WINAPI   *MYFUNC)(HWND,COLORREF,BYTE,DWORD);    
  MYFUNC   fun   =   NULL;  
  //取得SetLayeredWindowAttributes函数指针    
  fun=(MYFUNC)GetProcAddress(hInst,   "SetLayeredWindowAttributes");  
  if(fun)fun(this->GetSafeHwnd(),0,128【设置透明度值在0-255】,2);    
  FreeLibrary(hInst);    
  }