如何包装窗口的部分非客户区并控制其大小

1.有时候，我们需要包装窗口的标题栏，同时又不想让窗口的非客户区全部由自己来控制刷新，比如边框，菜单。

  从WM_NCPAINT中的参数wParam可以得到需要刷新的区域：

  hrgn = (HRGN) wParam;   // handle of update region

 因此，可以重载WndProc函数，对此区域中剔除标题栏所占的区域，代码如下：

 case WM_NCPAINT:
 {

    HRGN hrgnSrc; // handle to Src WindowDC update region
    HRGN hRgnCaption; // handle to Combine region
    HRGN hRgnNew; // handle to New WindowDC update region
    hrgnSrc = (HRGN) Msg.WParam;

    TRect *winrect =new TRect();
    GetWindowRect(ParentForm->Handle,winrect);
    TRect rc;
    rc= TRect(winrect->left,winrect->top,winrect->right,winrect->top+ GetSystemMetrics(SM_CYCAPTION)+3);
    hRgnCaption = CreateRectRgnIndirect(&rc);
    hRgnNew     = CreateRectRgnIndirect(&rc);
    if ((WORD)hrgnSrc > 1 && !RectInRegion(hrgnSrc, &rc))
    {
     DeleteObject(hRgnNew );
     DeleteObject(hRgnCaption);
     DeleteObject(hrgnSrc);
     delete winrect;
     break;
    }
    if ((WORD)hrgnSrc>1)
    {
      CombineRgn(hRgnNew ,hrgnSrc,hRgnCaption,RGN_DIFF);
    }
    else
    {
      HRGN hRgnAll = ::CreateRectRgnIndirect(winrect);
    CombineRgn(hRgnNew, hRgnAll, hRgnCaption, RGN_DIFF);
    DeleteObject(hRgnAll);
    }
    Msg.Result = DefWindowProc( ParentForm->Handle, Msg.Msg,(int)hRgnNew, Msg.LParam);
    DrawCaption();// custom draw caption
    DeleteObject(hRgnNew );
    DeleteObject(hRgnCaption);
    DeleteObject(hrgnSrc);
    delete winrect;
    return;
   }
2.怎么调整标题栏的宽度

  换言之，也就是调整窗口客户区的大小，自然也就修改了非客户区的大小。我们可以对WM_NCCALCSIZE消息进行处理，注意的是此方法不适用于窗口有主菜单的情况。

WM_NCCALCSIZE参数wParam和lParam的意义：

fCalcValidRects = (BOOL) wParam;        // valid area flag
lpncsp = (LPNCCALCSIZE_PARAMS) lParam;  // points to size calculation data
   or
lpncsp = (LPRECT) lParam;               // points to new window coordinates

具体代码：

case WM_NCCALCSIZE:
{// calculate window's client
 bool fCalcValidRects = (bool) Msg.WParam;
 if (fCalcValidRects)
 {
  RECT  rtSave;
  CopyRect(&rtSave,(LPRECT)Msg.LParam);
  rtSave.top+=TitleHeight - GetSystemMetrics(SM_CYCAPTION)-yEdge;
  if (HaveBorder)
  {
   rtSave.left +=4 -xEdge;
   rtSave.right-=4- xEdge;
   rtSave.bottom -=4- yEdge;
  }
  CopyRect((LPRECT)Msg.LParam,&rtSave);
 }
 else
 {
   RECT   rtSave;
   LPRECT prtClt;
   LPNCCALCSIZE_PARAMS  pNC;
   pNC=(LPNCCALCSIZE_PARAMS)Msg.LParam;
   prtClt=&(pNC->rgrc[0]);
   CopyRect(&rtSave,prtClt);
   CopyRect( &(pNC->rgrc[2]), &(pNC->rgrc[1]));
   (pNC->rgrc[2]).top+=TitleHeight - GetSystemMetrics(SM_CYCAPTION)-yEdge;
   rtSave.top+=TitleHeight - GetSystemMetrics(SM_CYCAPTION)-yEdge-1;
   if (HaveBorder)
   {
    (pNC->rgrc[2]).left +=4 -xEdge;
    (pNC->rgrc[2]).right-=4- xEdge;
    (pNC->rgrc[2]).bottom -=4- yEdge;
    rtSave.left +=4 -xEdge;
    rtSave.right-=4- xEdge;
    rtSave.bottom -=4- yEdge;
   }
   CopyRect(prtClt,&rtSave);
 }
 break;
}

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